How would ATC try to establish contact with a VFR craft? Example: I'm in a 172 tailed N1234A, on a pleasure hop between Hicks Field and Addison, circling around DFW International to the north, flying at 1500ft within DFW's Mode C veil under VFR (so I'm squawking 1200). The approach direction for the day also happens to be the north (this is common; prevailing winds in the area tend to be southerly). I'm staying outside DFW's airspace and therefore have not checked in with DFW Approach.

As I'm about to pass underneath "Area B" of DFW's space (which begins at 2000ft between 10 and 13nm from the airport sweeping across the northern approach), there is a 747 approaching low in the class B umbrella. It will pass above and in front of me, but still too close for their comfort, and so ATC wants to verify that I see the jumbo out my left window and perhaps suggest I descend.

Questions:

Was flying under the approach traffic of DFW my first mistake? Should I instead be heading around south (which would be a really big detour as I'd need to avoid Love Field's portion of Class B) or just contacting DFW Approach for clearance through Class B space?
Am I in the wrong for not having made prior contact with DFW Approach or Fort Worth Center in these circumstances, even though I'm operating VFR in class E/G space?
Should I even be this close to Class B in the first place (I'm 500 feet below it and 2 miles outside the surface footprint)? If not, what's a better altitude and range for me to have planned for? Outside 13NM from the airport, I'd be under Area H which starts at double my altitude, 3000 ft, but would also require me to enter or avoid Alliance's Class D space, and it'd take me quite a bit out of my way (since it's just for fun and logging hours, I might as well just touch and go at DTO if it'll be this much hassle to avoid DFW).
Would DFW or FW Center even bother trying to inform me of the situation, assuming I stay safely underneath Class B space and the 747 stays safely in it? One would think, being in contact with the 747, they could simply tell the jumbo to maintain minimum 2500 or 3000ft until 10nm out to maintain 1000ft minimum vertical separation, but my experience with boats says that if someone should yield right of way in this situation, it's the smaller craft (me).
Here are the title questions. How would DFW attempt to contact me? What frequency would I be expected to be tuned to? The emergency frequency is of course 121.5, but during normal flight along this path I could conceivably be listening to Fort Worth Center (122.65), DFW Approach (124.3), Addison ATIS or Approach, etc.
What would they say that I'd be expected to respond to, and how should I respond? I'm guessing they'd say something to the effect of "unknown VFR craft bearing 350 range 12 altitude 15, acknowledge and identify".

Long story short, ATC has no reason to contact you but if they were to try they'd probably use 121.5 (see below). You're not in their airspace and the whole purpose of that airspace is to ensure separation, so as long as you remain clear of it they won't be concerned about you although they'll probably report your position to the 747.

As for your specific questions:

That's your decision as PIC and no one else can make it. But I wouldn't spend much time in a zone where I'm at high risk of a wake turbulence encounter.
No, there is no requirement for you to be in contact with ATC in that airspace so you're not wrong. It would be good to get flight following if possible, but that's optional and might not be available anyway.
It's hard to say what "too close" means and it could change depending on the time of day, if you're thinking about traffic. Again, this is something that you as PIC have to determine.
They won't try to contact you since you're outside the class B and they have no reliable way to contact you anyway. And considering wake turbulence again, "too close for their comfort" is probably more like too close for your comfort :-) Aircraft size isn't a consideration for right of way (see 14 CFR 91.113).
They won't for the reasons above. And they also can't know if you have a working radio, which frequency you're on etc. But they would probably try 121.5 because a current FDC NOTAM states that you should be monitoring it if you can:

  ALL AIRCRAFT OPERATING IN UNITED STATES NATIONAL AIRSPACE, IF CAPABLE,
  SHALL MAINTAIN A LISTENING WATCH ON VHF GUARD 121.5 OR UHF 243.0.

The AIM also suggests and encourages all pilots to monitor it (e.g. section 6-2-4).

It's hard to say, the FAA's ATC instructions don't cover this situation (or I couldn't find it). But giving a specific bearing is unlikely (a bearing from what?) because you might not have the equipment to verify it so perhaps "12 miles north of DFW at 1500ft" would be more likely for the position part.

Of course, if ATC really, desperately, urgently needs to contact you - like if you fly straight through the class B without a clearance - then they can always request an interception. That would really ruin your day, so monitoring 121.5 if you can is probably a good idea.


61 vs 141: What's better for future US ATP? The pros and cons of each are all over the internet. Price and flexibility, which of the two routes looks better when applying for an airline regional or legacy, does it matter? More importantly which better prepares you?

Either one is fine, though I'd make sure you seek a good instructor for a part 61 and follow a part 141 syllabus (available through ASA, Jeppesen, King Schools, etc.) when you do yours to verify you covered all the bases.

At that stage of your training, future employers really won't care that much whether you did your training as a 61 or 141 student.  They are going to be much more concerned with your professional flying record and later certification and checkrides.


Why doesn’t runway 31R at JFK have a VGSI? All of the runways at JFK have a PAPI except 31R.

Why does 31R not have any kind of VGSI?

See this answer.  PAPI's are usually placed at the touchdown point for the runway.  By looking at this satellite photo you can see that the touchdown point is at the intersection of 31R and 22R-04L so there is no room for the PAPI.


Can Part 141 instrument simulated time be logged? I'm doing my IR rating in Part 141, and the school says you cannot log simulated time in the logbook, whereas in Part 61 they are allowed. Why?

The FAA's Advisory Circular 61-136B addresses this subject and explains how time on an advanced training device should be logged:

D.3 Logging Training Time and Experience.
Authorized instructors
utilizing an FAA-approved ATD for airmen training, pilot time, and
experience requirements are required to log the time as dual
instruction and as basic aviation training device (BATD) or advanced
aviation training device (AATD) time appropriately. Any columns that
reference flight time should remain blank when logging ATD time. ATD
time can only be logged as Instruction Received (Dual), Instrument
Time, or Total Time as reflected on the pilot time section of FAA Form
8710-1, Airman Certificate and/or Rating Application. Simulated
instrument time can be logged in an ATD, but only during the time when
the visual component of the training session is configured for
instrument meteorological conditions (IMC) and the pilot is
maintaining control solely by reference to the flight instruments.
Logging time in this fashion will allow a pilot to credit this time
towards the aeronautical experience and instrument experience
requirements as specified in part 61 or part 141. It is required under
§ 61.51(b)(1)(iv) that the type and identification of the ATD be
included when logging pilot time as described in the letter of
authorization (LOA). It is the responsibility of the flight
instructor, student, or certificated pilot to verify the device is
qualified and approved for training or experience requirements. It
would be appropriate for the person using the ATD to retain a copy of
the LOA. Evaluators such as Designated Pilot Examiners (DPE) are
instructed to request a copy of the LOA from applicants logging ATD
pilot time, to verify the time acquired in the trainer qualifies for
the minimum experience requirements for a certificate or rating.
Note: There are no restrictions on the amount of training accomplished and
logged in training devices. However, the regulatory limitations on
maximum credit allowed for the minimum pilot certification
requirements are specified by parts 61 and 141 and in the LOA. No
approvals or authorizations are provided for aircraft type ratings
using ATDs.


Can I use a 150mw green laser to scare pigeons and not interfere with air traffic? Pigeons are annoying since they make aggressive cooing noises near my house. Considering many options for their dispersal, it seems lasers are one options since for some reason the lasers drive the pigeons crazy. In one video pigeons are completely dispersed by a 150mw green laser, making it appear to be an attractive option for dispersing my pigeon problem.

However I am concerned that maybe the lasers will continue into the atmosphere past the pigeons, and will affect air traffic....Obviously this is not worth the benefit of dispersing pigeons.

Is this totally out of the question? Are there any rules of thumb one should follow here to be on the safe side to not affect aircraft?

There are cases where you can use a laser pointer safely, such as pointing out constellations in a dark field far from any air traffic, but as a general rule of thumb lasers should not be pointed skyward - not even to get rid of irritating sky rats pigeons.

Should you wind up illuminating an aircraft with your laser you can cause serious problems for the crew - inadvertent or not it could get you a visit from some very unhappy law enforcement officials.

There are many other ways to get rid of pigeons, some of which are used at airports and many of which are more effective (and safer) than your laser idea.
Your local Animal Control group may be able to offer some additional ideas.

(Avoid the "predator bird statue" idea - in my experience pigeons realize it's fake and use it as a toilet.)


Why do these aircraft in long term storage have air and power connections? With the Covid-19 crisis many thousands of passenger aircraft have been put in storage. In this  Bloomberg article from July 2019 shows several aircraft in what appears to be storage with covers on engines and cockpit windows. They also appear to be connected to an electrical supply and the engines to some sort of compressor.
Here is a screen shot of the image:
And a link to a large size version of the full image.
Another link to a different photo of stored 737MAX with similar connections.
The Airbus website describes requirements for long term storage, but mentions no connections to air or electricity.
Why are these aircraft provided with air and power?

Why do these aircraft in long term storage have air and power connections?

The photo is of 737MAX being stored in July 2019. Back then, airlines might still have hoped that this wouldn't be "long-term storage" at all!
Usually, airplanes being mothballed are stripped of corrosive / humidity-sensitive parts (e.g. the interior) as much as possible, stored in the dry desert, and it is considered acceptable if getting them back out of storage requires weeks if not months of refurbishment.
None of these three things seems to apply here. The photo doesn't look like it was taken in the desert, the airplanes are probably fully intact, and the airlines were hoping that with a simple software patch, they might be able to get them off the ground quickly again.
Therefore, they would have opted to, instead of preparing the airplanes for long-term storage, have them partially powered up, or use external air conditioning units. I would be willing to bet that those exact some planes are stored differently in July of 2020!


Have there been any 'proper' field trials of Automated Air Traffic Control? Have there been any 'proper' field trials of Automated Air Traffic Control?

Specifically, something that has been tested on larger aircraft and has come beyond the drawing board. By automated I'm implying that all decisions on movements are made by computers and instructions would be for instance transmitted digitally to the cockpit.

No

Short answer, but there has never been anything resembling a "proper" trial. There have been a few small scale, limited and tightly controlled trials, but nothing over any significant time frame, involving a significant number of aircraft, or even involving aircraft in "normal" use.


Can a non-citizen get a pilot job in Canada if they have an FAA CPL? I am an Indian national and considering taking CPL classes in the US. Upon graduation I should have around 250 hours under my belt and FAA licenses. Based on my citizenship status and FAA licenses, would any Canadian airline/general aviation employ me? (This is also assuming that I appear for the Canadian license conversion exam, clear it and have my licenses in order.)

Alternately, if anyone knows any other ways to build hours while in the US (like working as a flight instructor on an F-1 visa) please let me know. I need to build a good amount of hours before I can apply to any major air carrier.

Thanks.

It would be like taking any other job in Canada.  If you aren't a permanent resident/landed immigrant, you need to obtain a temporary work visa with job offer in hand.

In Canada you can hire on with a 2nd tier (Regional) carrier with lower hours than the US because there isn't the "Colgan Rule" that requires 1500 hours (US Regionals have complained bitterly about this, because there are situations where they are forced to take inferior candidates because he/she has the hours, and pass on a superstar that is 500 hours short).

The candidate market is becoming very tight.  Air Canada Jazz operates Q400s and CRJs and is taking pick of the litter kids right out of the colleges and puts them through a more comprehensive training program than the normal two-weeks-then-7-sim-sessions-and-a-checkride whirlwind type course, although off the street candidates will need more time.  West Jet Encore runs Q400s and has dropped their 1500 hour off the street requirement for new FOs down to 1000 hrs and is also running a special mentoring program with the colleges.


Does the main helicopter rotor blade shape affect noise? Most blades are squared off at the end. The Cobra fighting ship has pointed tips. Does this cancel out the "wop wop" noise? The reason I ask is that today I saw the Cobra in this news article. The tips are pointed. In 1968 I worked at Bell Aerospace making blades for use on Hueys and all had squared off tips as were tail rotors. Seeing this bird brought back memories.

Yes. Especially tip shape, which is optimized in most modern helicopters (and upgraded older ones) to reduce noise.
Basically, the blade tip shapes are optimized to reduce the noise caused due to blade-vortex interaction (BVI). From Parametric Study for the low BVI Noise BERP Blade:

The BVI (Blade Vortex Interaction) phenomenon,especially parallel interactions between the helicopter main rotor blade and the tip vortex, is the cause of significant noise and vibration problems in helicopter operation. In particular, the descent  and banked  turn  flight  conditions  are known to produce significant BVI.

This phenomenon is explained in this article in rotorandwing:

... higher-pressure air will spill out from under a rotor blade at the tip, get sucked toward its upper surface, and create a strong corkscrewing swirl of air, or tip vortex. ... an approaching blade will often come into the vicinity of a tip vortex left by a preceding blade. When the high-energy swirling air strikes the rotor blade, it causes a sudden change in angle of attack and an associated change in pressure on the surface of the blade. This is what creates the loud impulsive noise that can be annoying to those on the ground.

If the blades are designed in such away that the pressure change due to the BVI is reduced, the noise can be reduced. This is the reason for the differing shapes of modern helicopter blade tips. A good example is the Eurocopter Blue Edge concept, which Airbus claims reduces noise by 3-4 dB:

Blue Edge™ main rotor blade has a double-swept shape to change the blade-vortex interaction (BVI) that occurs at the tip of any helicopter blade – significantly reducing noise levels created during a typical descent profile.
This ... noise reduction technology has been validated ... flight trials using a five-blade Blue Edge™ main rotor on an EC155, showing a 3-4 dB noise reduction.

Eurocopter Blue Edge Wing; image from wired.com
That varying the tip shape will affect the BVI and consequently noise, was well known (for example, see the NASA paper Evaluation of Helicopter Noise Due to Blade-vortex  Interaction for Five Tip Configurations by Danny R. Hoad, which compares the sound produced by various tip shapes). However, with the advances in computer modeling and CFD, a number of modern helicopters incorporate blade tips that have been designed with the express purpose of reducing BVI and noise.


What would be a simple aerodynamics simulation software for a student? I have a project due 2 weeks from now that demands we make a glider using Styrofoam. I'd like to simulate the results as I plan my glider before I build it.

Which simple software, which allows importing a 3D model to do the testing on, can give me data on

CG,
CL,
lift,
drag and
reach

based on initial velocity, etc.?

If you have only two weeks it may be best not to go running into a maze, but you may wish to have simple and complex approaches running side by side.

As others have said, it would be helpful to know the parameters of your assignment.  Are they interested in the theory, or do they want to see something flying?

The most important thing will be the airfoil shape as far as lift and drag, but glider airfoils are easily obtained on the Net (airfoil tools). Next would be wing loading, which can be obtained from existing models and data from birds.  Design can be your choice, but starting from scratch, a standard sailplane planform will serve well.

Remember to have your CG near your Clift, slightly forward, and your elevator trim slightly up. For an indoor free flight glider a high aspect wing with some dihedral and an upright vertical stabilizer will help make it fly straight.

Although the theory behind gliders is well known, getting one to fly right will be a learning curve from scratch. Leave at least 2 days for test flights, and plan on extra Styrofoam and glue for repairs. Good luck!


Why doesn't ATC use a unified frequency for the same control area? If you have experience of getting flight following or flying instrument in the US, you might have noticed that approach and center controllers alternate between two or three frequencies for the same control area. For example, I get 118.1 from the tower for flight following one day, and the next day I get 126.0 for flight following for exactly the same route of cross country.

Why don't they just use one frequency for the same control area? Wouldn't that make their job much easier?

This situation is due to usually 2+ sectors being worked. Each sector will use its own frequency when split. When these sectors get combined, one of 2 things will happen. 1) The controller will just work with both sectors frequencies keyed up and be listening on both and transmitting on both and have everyone go to the approrpriate frequency for the sector they're in or near. 2) The controller wants everyone on one frequency and has everyone going into those sector's that they are working to be on just one frequency. Frequency congestion and capability(if the transmitters/receivers are different locations for the different frequencies) are also factors.


What is this hole in the nose of the A330? In this question, there is an image of a ladder leading to some hole in the bottom of the nose of an A330. What is that hole for?

Source

It is the avionic compartment access door as described in the Flight Crew Operating Manual!

  An inward-opening, manually operated, hinged door gives access to the avionics compartment. This door is in the lower fuselage, forward of the nose landing gear bay. A ladder is stowed inside the compartment adjacent to this door, which may be either be operated from the interior or the exterior.
  This compartment is also accessible from the cockpit, via a floor hatch located behind the Captains' seat. A fixed ladder in the avionics compartment for access from the cockpit.

Here is a drawing from the outside!

And here a view from the cockpit flight deck for an A340!


Can an aircraft owner legally replace an oil quick drain valve? The quick drain valve on our older Mooney has started leaking and making a bit of a mess.  We went to our local shop to asked them to schedule to replace it for us and they told us they are booked out several weeks and turning away any smaller jobs due to being understaffed -_-

I mentioned we do our own oil changes and he suggested that if we were handy enough to handle an oil change we could just remove the quick drain and replace it with an original plug and he was happy to give us one for free.  That would get us to our next oil change and we could get it replaced then.

Part 43 allows owners to do the oil changes and replacing the quick drain valve with a plug looks to be basically identical to the oil change process if you didn't have a quick drain valve in the first place: remove the plug, catch the oil, replace plug, add new oil.  But if I'm going to down that route anyway why not just grab a new quick drain off of aircraft spruce and put that in instead of the plug?

Are we on the right side of owner maintenance if we replace the quick drain with a plug as the A&P suggested?  How about if we replace the quick drain with a new one?  Or should we get a sign off from an A&P

This is what the FAR allows you to do as preventive maintenance if you are not a certified mechanic:

(c) Preventive maintenance. Preventive
maintenance is limited to the following
work, provided it does not involve complex
assembly operations:
(1) Removal, installation, and repair of
landing gear tires.
(2) Replacing elastic shock absorber cords
on landing gear.
(3) Servicing landing gear shock struts by
adding oil, air, or both.
(4) Servicing landing gear wheel bearings,
such as cleaning and greasing.
(5) Replacing defective safety wiring or
cotter keys.
(6) Lubrication not requiring disassembly
other than removal of nonstructural items
such as cover plates, cowlings, and fairings.
(7) Making simple fabric patches not requiring
rib stitching or the removal of structural
parts or control surfaces. In the case of
balloons, the making of small fabric repairs
to envelopes (as defined in, and in accordance
with, the balloon manufacturers’ instructions)
not requiring load tape repair or
replacement.
(8) Replenishing hydraulic fluid in the hydraulic
reservoir.
(9) Refinishing decorative coating of fuselage,
balloon baskets, wings tail group surfaces
(excluding balanced control surfaces),
fairings, cowlings, landing gear, cabin, or
cockpit interior when removal or disassembly
of any primary structure or operating
system is not required.
(10) Applying preservative or protective
material to components where no disassembly
of any primary structure or operating
system is involved and where such
coating is not prohibited or is not contrary
to good practices.
(11) Repairing upholstery and decorative
furnishings of the cabin, cockpit, or balloon
basket interior when the repairing does not
require disassembly of any primary structure
or operating system or interfere with an
operating system or affect the primary
structure of the aircraft.
(12) Making small simple repairs to fairings,
nonstructural cover plates, cowlings,
and small patches and reinforcements not
changing the contour so as to interfere with
proper air flow.
(13) Replacing side windows where that
work does not interfere with the structure or
any operating system such as controls, electrical
equipment, etc.
(14) Replacing safety belts.
(15) Replacing seats or seat parts with replacement
parts approved for the aircraft,
not involving disassembly of any primary
structure or operating system.
(16) Trouble shooting and repairing broken
circuits in landing light wiring circuits.
(17) Replacing bulbs, reflectors, and lenses
of position and landing lights.
(18) Replacing wheels and skis where no
weight and balance computation is involved.
removal of the propeller or disconnection of
flight controls.
(19) ...
(20) Replacing or cleaning spark plugs and
setting of spark plug gap clearance.
(21) Replacing any hose connection except
hydraulic connections.
(22) Replacing prefabricated fuel lines.
(23) Cleaning or replacing fuel and oil
strainers or filter elements.
(24) Replacing and servicing batteries.
(25) Cleaning of balloon burner pilot and
main nozzles in accordance with the balloon
manufacturer’s instructions.
(26) Replacement or adjustment of nonstructural
standard fasteners incidental to
operations.
(27) The interchange of balloon baskets and
burners on envelopes when the basket or
burner is designated as interchangeable in
the balloon type certificate data and the baskets
and burners are specifically designed for
quick removal and installation.
(28) The installations of anti-misfueling devices
to reduce the diameter of fuel tank
filler openings provided the specific device
has been made a part of the aircraft type
certificiate data by the aircraft manufacturer,
the aircraft manufacturer has provided
FAA-approved instructions for installation
of the specific device, and installation
does not involve the disassembly of the existing
tank filler opening.
(29) Removing, checking, and replacing
magnetic chip detectors.
(30) The inspection and maintenance tasks
prescribed and specifically identified as preventive
maintenance in a primary category
aircraft type certificate or supplemental
type certificate holder’s approved special inspection
and preventive maintenance program
when accomplished on a primary category
aircraft provided:
(i) They are performed by the holder of at
least a private pilot certificate issued under
part 61 who is the registered owner (including
co-owners) of the affected aircraft and
who holds a certificate of competency for the
affected aircraft (1) issued by a school approved
under § 147.21(e) of this chapter; (2)
issued by the holder of the production certificate
for that primary category aircraft
that has a special training program approved
under § 21.24 of this subchapter; or (3) issued
by another entity that has a course approved
by the Administrator; and
(ii) The inspections and maintenance tasks
are performed in accordance with instructions
contained by the special inspection and
preventive maintenance program approved
as part of the aircraft’s type design or supplemental
type design.
(31) Removing and replacing self-contained,
front instrument panel-mounted
navigation and communication devices that
employ tray-mounted connectors that connect
the unit when the unit is installed into
the instrument panel, (excluding automatic
flight control systems, transponders, and
microwave frequency distance measuring
equipment (DME)). The approved unit must
be designed to be readily and repeatedly removed
and replaced, and pertinent instructions
must be provided. Prior to the unit’s
intended use, and operational check must be
performed in accordance with the applicable
sections of part 91 of this chapter.
(32) Updating self-contained, front instrument
panel-mounted Air Traffic Control
(ATC) navigational software data bases (excluding
those of automatic flight control
systems, transponders, and microwave frequency
distance measuring equipment
(DME)) provided no disassembly of the unit
is required and pertinent instructions are
provided. Prior to the unit’s intended use, an
operational check must be performed in accordance
with applicable sections of part 91
of this chapter.


Is hypersonic flight possible with a Busemann's Biplane? The modifications to the Busemann's Biplane design reported in this article have proven that it is possible to design a modified Busemann's Biplane wing design that actually produces lift at supersonic speeds. Is it then possible to fly the same plane at hypersonic speeds of say Mach 10 (and ground speeds of above 10,000 km/h)? What are the other technical limitations?

The engines can achieve it and the air frame could be cooled, is noise once again an impediment at those speeds? Are there any effects on the human body for flying that fast given gradual acceleration? What about fuel, is it fuel efficient? Do we have a type of fuel that could power today's engine designs at those speeds given the complexities of using hydrogen?

Why Mach 10? Would Mach 3 or 4 not be enough? See here and here and here for the complications which arise at higher speeds.

The linked article is full of misrepresentations - of course will the Busemann biplane create lift at sub-supersonic speed (what is that, anyway? I read it as subsonic speed). Give it a proper subsonic airfoil and it will do so just like any other biplane, and even with the trapezoidal airfoil it will do so, albeit with more drag. It will also create lift and drag if operated at a proper angle of attack below its design speed (maybe that is meant by sub-supersonic speed, but the author never clarifies that).

Busemann biplane as shown in the linked article (source)

Did you note that the shock lines in the graph only occur between the two wings? That means that on the outer surfaces you will only see ambient pressure. The pressures internally cancel each other, and the result is that the Busemann biplane will not create any lift at its supersonic design speed in order to do its magic. As soon as it starts to create lift, it needs to create shock waves on the outside which will invariably be audible. That the researchers at Tohoku claim them to be 85% weaker is easy if they omit to mention to what they compare it.

Now look at the bulky passenger compartment on the top wing. This is clearly not optimised for supersonic travel (please compare it to the fuselages of the Concorde or the Tu-144 to get an idea what works).

No, this article is just utter nonsense.


Do you need a rotating beacon if you have strobes? If I were to replace my left nav light with a SkyBeacon ADS-B + strobe, could I remove the rotating beacon at the top of the tail?

As required equipment for night flight, that’s technically feasible to do as this can serve as an anti collision light, provided the aircraft still has position lights and landing lights.  However, if you’re flying a certified aircraft, unless you have an STC to deactivate the beacon, you cannot as it’s listed in the minimum equipment list for the aircraft.  You’d be opening a can of worms to do so and there really seems to be no significant advantage in doing so.


A Question about Departure Procedures at KLRU The Las Cruces International Airport has the following text in the Takeoff Minimums and ODP document:

  LAS CRUCES, NM

  LAS CRUCES INTL (LRU)
   TAKEOFF MINIMUMS AND (OBSTACLE)
  DEPARTURE PROCEDURES
  AMDT 2 16231 (FAA)
  TAKEOFF MINIMUMS: Rwys 4, 8, 12, 22, 26, 30, 2500-3
  for climb in visual conditions.

  VCOA: All runways, obtain ATC approval for climb in visual
  conditions when requesting IFR clearance. Climb in visual
  conditions to cross Las Cruces Intl southwest bound at or
  above 6500 on CUS VOR/DME R-038 to ZAXOX INT/
  DMN 27 DME. Continue climb in ZAXOX holding pattern
  (hold W, right turns, 094° inbound) to cross ZAXOX at or
  above MEA or assigned altitude for route of flight

What I don't understand is if these procedures are optional or required.  While I understand that part 91 doesn't have to abide by Takeoff minimums and ODPs, would a commercial carrier be expected to do the VCOA?  In IFR training they said VCOAs can be requested but not offered by ATC.  Would a commercial carrier be expected to do the VCOA or could they do a Diverse Departure?  Also do the Takeoff minimums only apply to the VCOA?

Link to document Here

The only takeoff departure at Las Crucas, NM (KLRU) is a visual climb over airfield (VCOA).

Typically you would depart the airport and visually see and avoid the obstacles around the airport while you climb.  If you are in IMC conditions (at this airport) you need 2500' ceilings and 3SM visibility to circle and climb above the airfield.  In essence, the procedure is for you to avoid the obstacles while you are climbing in a confined space.

ATC wants to know about your intentions of flying VCOA so they can plan accordingly.  It is one thing to climb over the airfield to the MEA vs. reaching the MEA 30NM from the airport.

From AIM 5-2-7

  A VCOA procedure is a departure option for an IFR aircraft, operating in VMC conditions equal to or greater than the specified visibility and ceiling, to visually conduct climbing turns over the airport to the published "climb-to" altitude from which to proceed with the instrument portion of the departure.  VCOA procedures are developed to avoid obstacles greater than 3 SM from the departure end of the runway as an alternative to complying with climb gradients greater than 200 FPNM.  Pilots are responsible to advise ATC as early as possible of the intent to fly the VOCA option prior to departure.


How was the "frozen wing flap grease" problem solved? (Antarctica, 2001 emergency evac) In the June 16, 2016 Washington Post news article A rare, risky mission is underway to rescue sick scientists from the South Pole difficulties of flying in and out of the south pole in winter are discussed. The article describes an earlier emergency evacuation in April of 2001:

  The replacement doctor for the station disembarked, and the ailing Shemenski clambered onto the plane. But as they started up the engines, the crew realized they couldn't take off. The Twin Otter's skis had stuck to the ice beneath them, and the grease on the wing flaps had frozen them in the fully extended position. While the station workers hacked at the ice on the skis, the plane's mechanic jerry-rigged the controls to allow it to take off. It was one of the longest, slowest take-offs any of them had ever attempted, but eventually, they were in the air.

How did the jerry-rigging of the controls of the De Havilland Twin_Otter allow it to take off from the south pole in winter with its flaps fully extended because of the frozen wing flap grease?

Is there a better description of the problem and the actual solution that was implemented?

note 1: According to the article, the current rescue mission can be monitored at https://flightaware.com/live/flight/CGKBO
update: apparently this hasn't actually been the case.

note 2: The article also says there are actually two planes involved in the rescue mission.

  Two small bush planes are flying to the South Pole this week to evacuate workers at the Amundsen-Scott research station — a feat rarely attempted during the middle of the Antarctic winter.

Flying with the flaps extended is perfectly possible, just inefficient. At that point they were probably just trying to get in the air, not worrying about their fuel efficiency or airborne speed. Otters normally land and take off with flaps somewhat extended. The main problem is that with flaps fully extended, acceleration will be low, so it will be a long, slow takeoff. One issue is that if the plane has any icing, being in a full-flap condition can lead to a stall.

Once things get down to -50F or below, stuff really starts to freeze. For conditions like that you need to start replacing grease with graphite lubricants. Even fuel freezes so the planes have to use special heaters.

Here is a more technical description of the event by an electrician:

  We then refilled the smudge pots and brought out tanks containing
  about 1,000 gallons of fuel to refuel the plane. They also brought out
  3 Herman-nelsons, portable diesel heaters used to warm up planes and
  other big equipment. At about 2:15AM, the plane was started but some
  of the hydraulics in the tail controlling the flaps were frozen. We
  called to get the Herman-nelsons back to heat up the flaps. They ran
  their engines the whole time, and we had to bring out another 100 or
  200 gallons of fuel.

  Finally, at about 5:00 AM, the plane was working right and was ready
  to go. But then it appeared the plane was stuck in the snow. So a
  couple of guys stood on a car-like vehicle with tank treads, and shook
  the plane's wing. This caused the whole plane to rock back and forth.
  But finally the plane broke free and taxied to the skyway. The plane
  turned around and took off and flew in the -64F air.

  Brother Aaron Coy, Local 48 Portland, OR Amundsen-Scott South Pole
  Station, South Pole, Antarctica

There are no hydraulics in the tail, obviously, so the electrician is confused about something. The hydraulic system in an ski-equipped Otter is used for the flaperons (in the wing) and for the ski controls.

Twin Otter at Casey Station


Does headwind on takeoff affect g force? I'm aware that headwind or tailwind does not affect rate of climb or descent but only the angle. I'm not sure if it affects the g force or not. I'd assume it affects g force because using trignometry, using SIN theta the vertical component increases as the angle increases. However a confirmation would be aappreciated.

In the takeoff run, the acceleration is less with headwind, but once in flight, the airplane flies within the mass of air. The fact that that mass may move in relation with the ground doesn't affect the magnitude of the forces involved in flight, so accelerations are not affected by the wind.


Do wings on a plane need to be in the same plane horizontally, or can one wing root be 6" lower than the other? Do wings on a plane need to be in the same plane horizontally, or can one wing root be 6" lower than the other?

The proposed application would be for a ultralight with high mount folding wings, where first 50% chord flaps would fold down 180 deg underneath the wings, reducing the "folded chord" to 50% of the full wing chord.  Then the tapered wings would scissor back about 120 deg over the fuselage and interlock like a scissor, so when the wings are folded up, they are roughly mirror the same shape as the fuselage.  One wing root would be about 6" higher than the other.

For example, with a 12" high spar root, and 3" thick wings, one 1/2 span would be mounted near the top of the spar, the other one, at the bottom on the other side of the fuselage

The left and right wing may be at different heights.  You'd suffer from interference drag at the joint between them, or extra induced drag from the two extra "wingtips" if there is no joint, but a slow ultralight can tolerate such drag better than most airplanes.  This may be the only asymmetrical design that Rutan didn't attempt.


Why are the minima for Cat A higher than for other categories at KSEA ILS 16L? I was looking at the KSEA ILS 16L approach (depicted below) and was wondering just why the minima are bumped up for Cat A aircraft (64 feet on both DA and HAT, as well as 200 feet of RVR).  Thing is, I've already checked Chapter 10 of the TERPS, and nothing in there says anything about approach-category-specific adjustments to ILS minima, nor does the Form 8260 for this approach say anything about the cause.  (This also makes the SA CAT I and CAT II/III procedures Cat A NA, which matters for aircraft that have a small aircraft CAT II ILS authorization IAW FSIMS 4.2.3.)  Furthermore, neither 16C nor 16R's ILS approaches have this feature, which is even stranger because you'd think that 16L and 16C are close enough together that their ILS OCSes would overlap, and they also use highly similar MAPs (climb to 900 on a heading, then intercept the SEA 161 radial, then proceed to TEBNE along that radial -- the only difference is the initial heading of 160 for 16C vs 165 for 16L).

What is doing this? Is there an obstacle there that is doing this only to small aircraft?  Is there some vagary of the TERPS I'm not finding? Is this an error?

The minima's are usually decided based on the Missed Approach procedure, which one of the criteria being obstacle clearance. I believe the answer lies in your question, its due to the heading course and altitude restriction on the MAP point. RWY 16L needs to climb straight 165 deg which puts you through the obstacle , whereas 16R Missed approach procedure heading can clear the '464' obstacle. . In either case Obstacle driving the change, Having CAT A with the lower speed in the heading of 165 deg it won't get you clear the obstacle. The PBN approaches are even marked higher for all aircraft type which can be inferred from other terminal charts.


Why did the B-29 have so much leftward torque at take-off? In this book, The Making of the Atomic Bomb by Richard Rhodes (p. 705), I read:

  [Paul Tibbets] eased the brakes [of Enola Gay] at 0245, the four fuel-injected Wright Cyclone engines pounding. “The B-29 has lots of torque in take-off,” he notes. “It wants to swerve off the runway to the left. The average mass-production pilot offsets torque by braking his right wheels. It's a rough ride, you lose ten miles an hour and you delay the take-off.” Nothing so rude for Tibbets. “Pilots of the 509th Group were taught to cancel torque by leading in with the left engines, advancing throttles ahead of the right engines. At eighty miles an hour, you get full rudder control, advance the right-hand engine to full power and, in a moment, you're airborne.”

I am not especially knowledgeable in aviation matters, but I believe that the torque is due to the B-29's four propellers all rotating in the same direction. Is that right? If so:

Why did this problem only arise during take-off?
Why did all propellers rotate the same way? Is this true for all propeller-driven aircraft with more than one engine? Why?
If the 509th Group's technique was so good (and apparently not especially complex), why did only they use it?

It didn't arise ONLY during takeoff, but it is most noticeable then for several reasons

The engines are at maximum power, therefore producing maximum torque
You've got a very good reason to need to be travelling in an exactly straight line (the runway)
You're travelling at fairly slow speed, so your vertical stabilizer is less effective - at higher speeds, the tail counteracts the torque more effectively (for this B-29 this occurs at 80mph, as mentioned). As soon as you get above 80mph, you can just input a little right rudder to counteract it.... B-29's only travelled below 80mph on takeoff and landing, so it wasn't a problem during flight, and during landing the throttles were at idle or very low power.

It isn't true for all aircraft with more than one engine now (although it is true for some), but it does still happen and was much common back in WWII - they didn't want the extra supply line complexity of two different sets of otherwise identical engines, when it could be solved with a bootfull of right foot. Note also that the B-29 had 4 engines, most modern multi-props only have two, and they're closer to the fuselage, which reduces the effect
I think you're misinterpreting the source: he's not saying this technique was unique to the 509th, just that they were taught the technique. The very fact he says they were taught it, rather than "came up with" it, suggests it was known elsewhere. The 509th are only referenced here because that's the group Tibbets was part of, it's unrelated.


Why does instability in pitch lower trim drag for an aircraft with a tail? I have a hard time figuring out why a longitudinally unstable aircraft has a lower trim drag. This seems to be a thing especially in fighter aircraft, so does it have to do anything with supersonic flight as well?

It might be helpful to look at this article from Boldmethod.

The basic idea is that the farther away the center of gravity is from the center of pressure (or center of lift depending on your terminology) the more lift the horizontal stabilizer will have to generate.  The more lift an airfoil has to generate will result in more induced drag.  Trim drag is specifically the induced drag created by the horizontal stabilizer.  The horizontally stabilizer can actually produce both positive (upward) and negative (downward) lift but the negative lift has the even worse affect of requiring the wings to create more lift to compensate for the downward lift as demonstrated in the Boldmethod article.

Having the center of gravity at the center of pressure also allows the aircraft to be more maneuverable since less force is required from the horizontal stabilizer to initiate a maneuver.  This is why fighter jets tend to be longitudinally unstable and use fly-by-wire to compensate for it.


What are the different kinds of de-ice fluid? When frost adheres to the airplane or it is snowing, you need to make sure the airplane is clean when you depart.  You've probably seen the trucks spraying aircraft in the winter before departure, but what are the spraying it with?

I know of at least 4 types of de-/anti-ice fluids but perhaps there are others.  What does each fluid consist of and what is its function?  How do I know if these fluids are available at an airport I plan to operate from?  Are there limits in how soon I must depart once fluid is applied?

Fluid Types

Wikipedia contains a good summary of the different types of fluid:

  Types

  Type I fluids have a low viscosity, and are considered "unthickened". They provide only short term protection because they
  quickly flow off surfaces after use. They are typically sprayed on hot
  (130–180°F, 55-80°C) at high pressure to remove snow, ice, and frost.
  Usually they are dyed orange to aid in identification and application.
  Type II fluids are pseudoplastic, which means they contain a polymeric thickening agent to prevent their immediate flow off
  aircraft surfaces. Typically the fluid film will remain in place until
  the aircraft attains 100 knots or so (almost 200 km/h), at which point
  the viscosity breaks down due to shear stress. The high speeds
  required for viscosity breakdown means that this type of fluid is
  useful only for larger aircraft. The use of type II fluids is
  diminishing in favour of type IV. Type II fluids are generally light
  yellow in color.
  Type III fluids can be thought of as a compromise between type I and type II fluids. They are intended for use on slower aircraft, with
  a rotation speed of less than 100 knots. Type III fluids are generally
  light yellow in color.
  Type IV fluids meet the same AMS standards as type II fluids, but they provide a longer holdover time. They are typically dyed green to
  aid in the application of a consistent layer of fluid.

  Chemical Composition

  The main component of deicing fluid is usually propylene glycol or
  ethylene glycol. Other ingredients vary depending on the manufacturer,
  but the exact composition of a particular brand of fluid is generally
  held as confidential proprietary information.

Call ahead to the airport to see what kind of deice/anti-ice fluid that they have because each one is different.

Time Limits

Every year, the FAA publishes tables which include information about how long the various deice fluids will provide protection under various weather conditions.  Here is an example table:

For this particular fluid (ABAX ECOWING AD-49 Type IV) we can lookup a specific example such as:

-10 Degrees Celcius
75% fluid and 25% water
Light Snow

This shows that the fluid will provide protection for 1:40 to 2:05. If you are delayed longer than that, you will need to deice again.  Since every part of the aircraft needs to be protected, the timing starts when they first start spraying the aircraft.  Note that other types of fluid (particularly Type I fluids) have much shorter holdover times than this, so be careful and make sure that you check!

Resources

OFFICIAL FAA HOLDOVER TIME TABLES WINTER 2013-2014
AC 120-60B - Ground Deicing and Anti-icing Program


Could you help me identify a sound that began before pushback? A couple of weeks ago I flew with SAS on one of its B737 (I believe -600 or -700). A few minutes before pushback and engine start, a rather annoying, high-pitch sound began - imagine a whining electric motor. At first I thought it was the sound related to closing the cargo door and I expected it to stop after a few seconds. It didn't, and then I began wondering whether it was something related to the APU. The sound remained the same even after engine start - and indeed for the remaining of the flight, though the engine sound somewhat covered it (or at least I got used to it, I don't know).

A uniformed pilot was also in the passenger cabin and he didn't seem at all perturbed, so I assume the sound wasn't anything out of the ordinary. And yet, I've been traveling for decades and I can't recall ever hearing this before.

Any ideas what it could be?

Well, expanding off my comment above, I was boarding a flight with Delta and the pilot said over the PA that the people sitting over the wing should not be concerned about a whining sound that they would hear in a few minutes as it was the hydraulic pumps working.


Why do engine cowl lips appear larger and more blunt on the sides than on the top and bottom? I was looking into engine nacelles. I was not able to understand the design shape of it

Why is it that in most aircraft, the engine cowl lips on the side are bigger (more blunt) than on the top and bottom.

Images of 767 and 777 aircraft that I looked at show pretty uniform lips all the way around. This 757 engine (image below) looks thinner on the sides, which is the opposite of what you have seen.

The shape of the cowl (and lip) is going to depend mostly on the shape of the nacelle. The 757 engine (image above) has engine accessories at the bottom of the engine, which requires a thicker nacelle to cover, which requires a larger radius on the cowl lip to streamline. As discussed in this question, the 737 engines have a unique shape to provide ground clearance, so the accessories are pushed to the sides.


Is smart phone's GPS accurate enough to calculate airplane speed? Around seven years ago, I did airplane speed measurement. I activated the GPS on my tablet and I monitored the speed, especially when the airplane touched the ground (runway). I found that the airplane touched the ground with speed 420kph, which it was fast enough. The measurement was probably not 100% accurate, but I could feel that the airplane was landing and touched the ground quite fast.

My question, how accurate is measurement with GPS, especially using GPS installed on smart phone? If I need to calibrate, how to calibrate?

Edit:
The airplane was Boeing 737. Not sure the series.

That landing speed sounds rather high.  There's a regulatory maximum landing speed for airliner type aircraft, and as I recall, it's typically not far from 150 kt (240 or so km/hr).  Since it's unlikely the airplane you were in was actually flying at more than double normal speed at landing (and 180 kph will seem pretty fast to your own senses) I'm inclined to believe there was an error in your measurement.

The GPS in a tablet, reading from inside the airplane, is subject to a number of error factors.  First, even in good reading conditions, the tablet's position is generally only good to (in my experience) around 50 m; second, from inside a metal fuselage, there may be path-length errors, satellite changes, and other errors on top of the accuracy limitation of your device.

This level of positional error can add up to a large percentage error in calculated speed.

The GPS installed in aircraft have better software and can fix location more accurately, as well as more regular position checks which give more accurate speed calculation.  Those instruments make a good check against the pitot/static airspeed system.  A smartphone or tablet GPS, probably not so much.


Does a GPS OBS selector use magnetic or true courses? Under GPS navigation, when we are using the OBS to tune courses. Are these courses magnetic or true?

Magnetic, except for places on Earth where it would be truly ridiculous (such as high latitudes).

Basically, you want to navigate with one reference or the other, no matter which method you are using, to avoid confusion. Using magnetic reference is somewhat of a legacy: it's natural to use it when your primary method of navigation is a compass. Or even not a primary: stars and INS are referenced to True, but the pilot should be able to fall back on the compass at any moment (and cross check the instruments), so a correction (= variation) is always maintained.

GPS naturally works in True coordinates. But to provide 'backward compatibility' it also calculates Magnetic track. To do that, the avionics must maintain a current database of magnetic variation across the globe.

Furthermore, remember that GPS cannot really measure the heading, it can only measure the track. Heading is still measured using gyros, which are periodically corrected using magnetometer, i.e. the same compass.

Modern avionics can be switched between Magnetic and True references (see, for example, the G1000 guide). So technically the answer to your question would be 'it depends on the mode', but usually it is expected to be Magnetic.


How does one specialize in a certain sub-field of aerospace engineering? I want to become an aerospace engineering but want to be specialized in Aerodynamics. How do I do this in college?

I'm going to speak for a North American post-secondary experience. The simple answer is, you don't get to specialize in any particular domain within aerospace engineering as an undergraduate, even if your major is aerospace engineering. Why? Because you don't know anything yet for you to specialize. How can you know what you like, if you don't know anything yet?
The first two years of college are foundational studies, during which the courses and materials are more or less the same across any engineering field. You mentioned aerodynamics. Well, you can't do aerodynamics if you don't know linear algebra, vector calculus or basic fluid dynamics. The last two years would be more tailored to your major, but these will only give you a general gist of all the major domains that aerospace touches.
You get to specialize once you enter industry, or if you choose to pursue even higher educations (Master's, PhD, professorship). Whatever it is, what you ended up specializing will probably be very different than what you thought you'd be doing at the start of college, either because of change of interest (now that you know what the fields actually are), or monetary reasons (field A is more lucrative than field B), or pragmatic reasons (because field A has N openings and field B has zero).


Why would this A-10 Thunderbolt be flown over rural New Hampshire? My mother took this photo on December 29th, 2004 on a hill near Groton, New Hampshire. It appears to be an A-10 Thunderbolt, but it's difficult to tell whether or not it's armed. According to her it circled three times close above the hill before going out of sight.

The hill, as well as Grafton County as a whole, are not very populated, and there are no military bases around the area for hundreds of miles. Newspapers for the area on that day show no information that I can see. Can anyone think of a reason for an A-10 to be flown over this location on this date?

Practice makes perfect!

Groton, NH (along with a large chunk of rural New Hampshire further off to the north) sits more or less under an area of military Special Use Airspace called the Yankee 1 and 2 Military Operating Area complex, or MOA for short:

(If you're wondering why Groton is not on the map, ask FAA/NACO -- it's about at the bend in the road WNW of Hebron, right under the southern edge of the Yankee 1 MOA.  The snippet was taken using vfrmap.org.)

These areas of airspace are used by US military tactical pilots to practice their tactical maneuvers (such as "dry" practice bomb and strafing runs, and air combat maneuvering) without getting in the way of other airspace users -- high-performance jets making sharp maneuvers don't mix well with slow little propeller planes or not-so-maneuverable airliners!

As to why the pilot was circling?  They were probably killing time, waiting for their practice partner to show up, or the MOA to free up so they could use it.  Also, the airplane in the picture looks to be unarmed -- on one side is an empty pair of Sidewinder rails, while the other side carries a pair of targeting and countermeasures pods.

So, what your mom saw was a small part of our military keeping their gun oiled and ready, so to speak -- practice makes perfect, after all, and the airspace over rural parts of the US is about the only place in this country non-busy enough to serve as a suitable practice area.


Is there a limit to the possible altitude for electric jets? So I was thinking about Elon Musk's supersonic electric jet idea. Assuming we have sufficiently energy-dense batteries, where would the limits be in terms of speed and altitude.

His logic seems to be: electric (fan?) propulsion doesn't need oxygen -> can go higher -> less friction -> need less power and thrust to maintain airspeed compared to traditional jet

Question: is there some kind of limit for altitude and TAS? I mean suppose the Concorde would be retrofitted with batteries and electric fans. Instead of mach 2 cruising at 18300 meters, assume it would climb to 30km, or even 40km. Air density at 18.3km is 0.115 kg / m^3, at 30km it's 0.018 kg / m^3 and at 40km it is 0.0039 kg / m^3.

So 0.0039 / 0.115  = 3.4%. Meaning the resistance at 40km would only be 3.4% compared to 18.3km. Would that mean the power or thrust requirement to maintain mach 2 would only be 3.4%? Or is induced drag becoming significant at that point? Or maybe it would even stall at mach 2 if flying 40km high?

I mean somehow there must be limits, otherwise we could just fly higher and higher and fly with 0 thrust and still maintain mach 2 (not talking about space flight here)?

That electric propulsion needs no oxygen is of little help for flying high. The composition of the atmosphere does not change too much with altitude, so it is the low atmospheric density which limits maximum altitude. We had this discussion before, and indeed solar-electric propulsion helped to reach record altitudes: The AeroVironment Helios set a record at 29,524 m which will be hard to break.

Supersonic speed helps to fly high - while subsonic designs run into the coffin corner, supersonic flight helps to maintain high dynamic pressure even at altitude. However, the energy requirements for doing so will require an energy density of the batteries which is several magnitudes above what is currently possible. If you only want to go fast, the current limit with electrical propulsion and already rather generous assumptions is somewhere around Mach 2.

Flying higher does not reduce the thrust requirement since the same lift has to be generated. The best lift to drag ratio is achieved in subsonic flight. Going supersonic means crossing a drag peak, but beyond that the maximum possible lift to drag ratio is well below that at subsonic speed and decreases again with increasing Mach number.

Mr. Musk is clearly out of his competence when he claims that supersonic electric airplanes are viable, even with the progress in battery technology to be expected in the next few decades.


Would this work to reduce turbine engine spool times? In this answer to a question about reducing engine spool-up time, Peter Kämpf said:

  When more thrust/lift is needed, the pilot adjusts pitch and fuel flow to set the desired thrust/lift level. Since the engine is already running at top speed, the change is not delayed by inertial effects.

It seems to me that landing mode or critical mode switch for the engines which would cause the FADEC to spin-up the engine and control power by fuel flow instead would eliminate the lag and increase the likelihood of survival during critical flight regimes.

As an example, encountering a micro-burst during landing will leave the plane wanting power as it flys out of the burst and has a tail-wind, often at low power and low altitude. If, in that situation, the pilot applying additional throttle increased the fuel flow and gave immediate power instead of having to wait for the engines to spool, it seems that would be very advantageous.

Have I understood the concepts correctly, and, if so, what drawbacks to this system might I be missing?

Short answer: no, none of what you describe is possible with current jet engines. You need more fuel because the angle of attack for your prop is increased, not the other way round.

Let's first go into some (simplified) detail how the turboprop works. A turboprop is basically a gas turbine engine with a propeller stuck on the axle. The propeller is the bit that converts the torque and rpm of the engine shaft into a forward thrust. The amount of forwards force is determined by RPM and blade pitch. This means that, even though you're at high RPM, you can 'feather' your propeller so that it doesn't produce any forward thrust (blades flat). At the same RPM, you can just put your blades so that they produce a lot of thrust. Of course, this comes at the cost of increased drag, so the engine has to 'work harder' to maintain RPM. This, in turn, is achieved by injecting more fuel.

Now, to a turbojet. For a turbojet, the thing that produces thrust is exhaust gas going backwards real fast. This is achieved by burning fuel so that the gas gets hot and expands, so that it wants to get out of there as fast as possible. For this, a jet engine needs a lot of air. It sucks in this air by a series of compressors at the front of the engine. Then, some fuel is injected, and after that there are some turbines that make sure the compressors can, and after that there's a nozzle that converts the leftover energy into backwards gas velocity. Now, we want to increase the thrust. This means that gas has to get out of the back faster. Since the nozzle is generally fixed, this means that you just have to get more air out of the back (just like a garden hose with the tap half open or full open). This means that we'll have to suck in some more air from the front, burn some more fuel to make sure the engine keeps spinning, and more air will come out of the back.

Simply increasing the fuel flow doesn't work. Jet engines operate 'lean' (more air than necessary), and the extra fuel you suddenly inject will burn up with all the excess air, which might blow up your engine. If your engine doesn't blow up, you're left with too little air to burn all the fuel, and you'll get a lot of nasty things like soot, carbon monoxide and unburnt fuel coming out of your exhaust. This means you just inject some extra fuel, wait for the engines to 'spool up' so they suck in more air, and like that gradually increase your engine RPM and linked to that the gas velocity.

Two things remain: why use fixed nozzles? This is because physics dictate that, for engines to be efficient, the exhaust velocity needs to be as high as possible; in practice, the exhaust velocity will be as close as possible to the speed of sound in the hot flue gas. Using a variable nozzle would mean that your engine never works efficiently at half power. Furthermore, it adds complexity, weight and thus costs more.

Another thing: I discussed turbojets, not turbofans. In theory, one could have variable blade pitch on a jet engine. However, remember that the fan is not just for thrust (even though high-bypass engines are generally more efficient), but also to make sure enough air enters the compressors; 'feathering' them would mean that your engine might not get enough air. However, your engine would need a lot of air, because it needs to operate very lean to make sure it can handle the extra fuel flow for when you increase the blade pitch. Furthermore, a variable pitch on all blades would mean a lot of complex engineering, which would make the engine a lot heavier.

Long story short: one could design jet engines with variable pitch, but the above wall of text is only the beginning of why that is an engineering nightmare. Without variable blade pitch or nozzles.


How does the airflow around winglets reduce drag? I am familiar with the basic aerodynamics of wingtip vortex generation and I know that winglets reduce drag by reducing wingtip vortex generation.  I have never seen any illustration of exactly how winglets interact with wingtip vortices to do this.  I have also heard there is a small thrust component to the winglet's lift but am also unable to visualize this as well.  The multiple designs in use are confusing.  Why not just curve the end of the wing down to inhibit the vortex from spilling upwards?

This video perfectly explains what happens, except it doesn't use winglets, but different shape of the wings, but the idea is the same:

https://www.youtube.com/watch?v=CnvIf3vFEYA

What the video describes is when wings don't have winglets, air flowing under the tip of the wing escapes to the side of the wing and upwards, creating a vortex which reduces lift. Addition of winglet reduces the vortex and thus increases lift.

In the video however, new type of wing is shows that doesn't require winglets all together.


FAA: May I log as cross-country a flight with two or more short legs? Consider a hypothetical flight plan from Redstone to Cullman to Gadsden and back to Redstone. This flight would have legs in order of 26, 42, and 52 nautical miles.

14 CFR 61.1 provides

Cross-country time means—
…
(ii) For the purpose of meeting the aeronautical experience requirements (except for a rotorcraft category rating), for a private pilot certificate (except for a powered parachute category rating), a commercial pilot certificate, or an instrument rating, or for the purpose of exercising recreational pilot privileges (except in a rotorcraft) under §61.101(c), time acquired during a flight—
    (A) Conducted in an appropriate aircraft;
    (B) That includes a point of landing that was at least a straight-line distance of more than 50 nautical miles from the original point of departure; and
    (C) That involves the use of dead reckoning, pilotage, electronic navigation aids, radio aids, or other navigation systems to navigate to the landing point.

The original point of departure is Redstone Army Airfield, and Northeast Alabama Regional is farther than 50 nautical miles away. Would the entire flight count toward the cross-country experience requirements for a private pilot certificate, commercial pilot certificate, or instrument rating? Must the pilot fly the 50+ nm leg first?

From a 2008 FAA interpretation sent to E. Thomas Sisk:

… cross-country flight time is defined as time acquired during a flight that includes a point of landing that is at least a straight-line distance of more than 50 nm from the original point of departure, not the original point of any flight leg. There is no requirement that any specific leg must be 50 nm. Moreover, a cross-country flight may include several legs that are less than a straight-line distance of more than 50 nm from the original point of departure. Nevertheless, at least one leg of the cross-country flight, however long by itself, must include a point of landing that is at least a straight-line distance of more than 50 nm from the original point of departure (i.e. of the flight, not of that particular leg).
Given the above analysis, the answer is each cross-county flight used to meet the aeronautical experience requirements under 14 CFR §61.1 (b)(3) must include one leg that includes a landing that is at least a straight-line distance of more than 50 nm from the original point of departure.

From the above, it is pretty clear that the order of flying does not matter and you can log the whole flight.
Also, see this AOPA response.


What are the ways to burn fuel faster in case of emergency without fuel dumping system? In many cases, the maximum landing weight of an aircraft is lower than the takeoff weight due to the amount of fuel it carries.

While some aircraft have fuel dumping systems, others like the A320 family and Boeing 737 do not, and so have to cycle nearby until they have burned enough fuel. (And in case they have to land immediately, they will simply to, but need further inspection due to the high stress on brakes and landing gears)

My question is: If an aircraft has to cycle to burn fuel, are there measures to burn fuel faster? Lower altitude requires more thrust and so needs more fuel, but are there more ways? Like a slight air brake setting?

This question (sorry to say) is sort of moot because:

if you have an urgency to land (e.g. cargo fire), you don't care if you are overweight and you'd land anyway
if you have time to dump fuel, the situation isn't as desperate, and you can easily wait just a bit longer.

The large jets (e.g. Airbus A380, Boeing 777) have a fuel dumping system because, with full fuel, these planes can travel up to 12 hours or more! That is to say, if you don't dump fuel, you might have to fly around all day to get down to your normal landing weight.

Airbus A320 and Boeing 737 are different: they usually fly 1~3 hours route, and may stretch to 6 hours on a full tank. So, to begin with, you need less time to burn fuel. Plus, these (relatively) small planes can land on shorter runways, which means your airport choice will not be as restricted as with a large jet.

Now, as to actually answering your question......

Flaps and gears have speed restrictions. You cannot fly full throttle with these deployed. That being said, if the pilots put the airplane in landing configuration (full flaps + gear down), drag will increase significantly and they will need more thrust to maintain altitude and airspeed.

You can technically achieve that with spoilers, but it's dangerous. Spoilers destroy lift, so what you're really doing is reducing the effectiveness of your wings and compensate that by flying faster and/or increasing your angle of attack.

Then again, if you're desperate, just land right away......


Are you cleared to next altitude when you get "direct" while flying SID? Let's say you just took off from the TACOMA airport and were flying ATOME TWO DEP. ARRIE transition. The Seattle tower instructs you "direct to ZUMBI" and to contact Departure, and you contact Departure and report "Departure, N1234, passing 2000, direct ZUMBI." If departure just replies "N1234, Departure, Radar contact," are you cleared to the next altitude of KIMSH (at or above 10000ft) or should you maintain 9000 until Departure gives you higher?

As an example, say you receive an IFR clearance from clearance delivery prior to departure such as: "N1234 cleared to Los Angeles Airport, ATOME TWO DEPARTURE, ARRIE Transition, Q-One Forty-five, climb via SID, Squawk 2252, etc." Then, after passing 2000 ft. if the tower controller instructs you to "proceed direct ZUMBI" then he/she (controller) should issue you an altitude assignment because you are being taken off of the lateral path of the SID.  In the alternative the controller could assign an altitude by using the phraseology (or similar) "N1234 proceed direct to ZUMBI, climb via the ATOME TWO departure." The "climb via" verbiage in this sequence is the equivalent of assigning an altitude.

After switching frequencies to the radar controller he/she should instruct you (for example) "after ZUMBI climb via SID" (assuming that ATC wants you to meet the KIMSH restriction and climb to the published Top Altitude of 15000 ft).

Here is some information from the ATC Controller's Handbook 7110.65W, para. 2-6-4, g. 2 and the associated Note: (Air Traffic Controller's handbook, 7110.65W)

(Although the reference paragraph and note, as it is published in the controller's handbook, is an example when a deviation around weather is necessary, the principle underlying my explanation is the same (there is just not an example similar to the circumstances you describe in your question).

  When approving a weather deviation for an
  aircraft that had previously been issued a crossing
  altitude, including Climb Via or Descend Via
  clearances, issue an altitude to maintain along with
  the clearance to deviate. If you intend on clearing the
  aircraft to resume the procedure, advise the pilot.

  NOTE−

  After a Climb Via or Descend Via clearance has been
  issued, a vector/deviation off of a SID/STAR cancels the
  altitude restrictions on the procedure. The aircraft’s Flight
  Management System (FMS) may be unable to process
  crossing altitude restrictions once the aircraft leaves the
  SID/STAR lateral path. Without an assigned altitude, the
  aircraft’s FMS may revert to leveling off at the altitude set
  by the pilot, which may be the SID/STAR’s published top or
  bottom altitude.

Also, from the FAA's Pilot/Controllers Procedures & Systems Integration Workgroup FAQs regarding "Climb Via" procedures, here is an applicable Question and Answer (FAQs Climb Via):

  Q.
  I’m on a climb via clearance and the controller vectors me off the procedure.  Do I continue to “Climb Via?”

  A.  NO.  You are laterally and vertically off of the
  procedure.  The controller will issue an altitude to
  maintain and provide a further “expect” clearance.
  Note: Request an altitude to maintain if the
  controller does not provide one

The main point is that a clearance to fly a SID that contains a Top Altitude and verbiage that includes "Climb Via" assumes that you will fly the lateral route as published, thereby committing you to meet the altitude restrictions.  If you are taken off of the published lateral routing ("cleared direct" to a fix somewhere down-range on the SID) the controller needs to issue you an altitude assignment since you (while proceeding direct to ZUMBI) are no longer on the published SID lateral route. In the alternative the controller could assign an altitude by using the phraseology (or similar) "N1234 proceed direct to ZUMBI, climb via the ATOME TWO departure." The "climb via" verbiage in this sequence is the equivalent of assigning an altitude.

From the NBAA Access Committee briefing regarding "Climb Via" procedures:
(NBAA Climb Via Briefing) showing ATC Phraseology when being cleared direct to a fix on the SID.

Pictorial display from the NBAA briefing (see link above) of pilot/controller responsibilities and phraseology when being cleared direct to a (down-range) fix on the SID after departure:

If the controller did not issue me an altitude instruction ("maintain," "climb via," etc.) upon taking me off of the SID I would have asked for one.

Here is a link to the ATC Controller's Handbook (7110.65W) so you can review the reference noted above. Also, here is a link to a FAQ's publication regarding Climb Via Climb Via FAQs


What can cause a sudden jump in Indicated Air Speed? My aircraft heading is 321 with constant Static pressure, wind speed and steadily increasing Ground Speed.
Meanwhile, there was a sudden jump of 10kts in IAS from 140 to 150 kts withing a span of 1 sec.
For this span, Wind direction is rapidly changed from 176 tp 300 degree A.

Is wind direction is cause for IAS jump ?

Yes, exactly, the change of wind direction is the cause for your sudden increase of IAS.

I have marked your aircraft heading with a magenta arrow and the direction the wind comes from with a brown arrow. So, you are going 140 KIAS at this moment and you have a steady 5 knot tailwind. That means you have a GS of roughly 145 kts (we will ignore air density and that it's not a perfect tailwind in this example).

Now the wind direction changes all of a sudden.

You have now got a nearly direct headwind. That means there are in total 10 kts more worth of air going into your pitot tube and thus indicating 150 KIAS. That's because your aircraft lost the 5 knots tailwind and at the same time got a 5 knot headwind. Because of the fast wind direction change, the aircraft kept its "momentum" and the airspeed increases by double the wind speed.


Do the F-18's leading edge flaps deflect symmetrically in rolls? When the F-18 Hornet does rolls, do the Leading Edge Flaps (LEFs) deflect symmetrically or is the deflection different on the left and right LEFs?

Quoting the F/A-18A,B,C,D Flight Manual A1-F18AC-NFM-000, I-2-42

  2.8.2.8 Control Augmentation System (CAS) [...] The lateral control system uses ailerons, differential
  trailing edge flaps, differential leading
  edge flaps, differential stabilator, and rudders to
  achieve the desired roll characteristics. Scheduled
  air data roll rate feedback is used to augment
  inherent airframe roll damping. At high
  airspeeds, aileron travel versus stick movement
  is reduced and the ailerons do not deflect above
  600 knots. Differential stabilator and differential
  trailing edge flap travel is reduced at high speed
  to prevent exceeding structural limits. The leading
  edge flaps deflect differentially up to ± 3°
  when below 30,000 feet and above 0.7 MACH. Differential flaps are not used in the takeoff or land modes nor above 10° AOA in the auto flaps
  up mode. At low airspeeds, aileron and differential
  stabilator travel are reduced with increasing
  AOA to minimize adverse yaw.

In short: Yes the F18 uses differential (asymmetric) deflections on the leading edge flaps and trailing edge flaps but the scheduling depends on angle of attack, airspeed and Mach number.


What are the differences between the Avro RJ85 and the BAE 146-200? As far as I understand, the Avro RJ is a newer version of the BAE 146? What are the exact differences?

The main difference between the Avro RJ and the BAe-146 is the engine- The RJ has Honeywell LF 507-1F, which is developed from the Lycoming ALF 502R-5 used in 146. The main difference between the engines is that the 507 has more LP turbine stages (2 Vs 1), sightly more thrust (31.5 KN Vs 31 KN) and has a single-channel FADEC with hydro-mechanical backup.

Visually, the 146-200 has a small triangular bump in the rear fuselage to prevent tailstrike, while it isn't there in RJ85.


How do I select an aircraft mechanic? So Uncle Bob just died and left me 3.14 million dollas.  Or else I hit the lottery, or what have you.  Whatever the case may be, I've decided that today is the day I buy myself an airplane.  Harrison Ford has one and by God I want one too.  This means that I need a mechanic.

We can assume that I don't already know any mechanics (For the purposes of the question, we can assume I soaked my home in Cristal, tossed flaming $100 bills at it until it burned down, and then moved to Beverly Hills, away from all the little people), so:

How do I find a mechanic or maintenance shop to keep my privately-owned aircraft airworthy?

The key when selecting an aviation mechanic or shop to maintain your newly purchased plane is "time in type": You would not take a Cessna 172 to the United Airlines maintenance facility at JFK, not would you take an A380 to the local Cessna service center (even though it would be perfectly legal to do so).

If you're buying a new aircraft (of any type) the manufacturer will be able to recommend an authorized service center for you, and you'll probably want to use an authorized service center (especially for warranty work).

If you're buying a used aircraft you can still contact the manufacturer and ask about authorized service centers. They will usually be happy to give you a list of places near you that can work on your aircraft, and who are blessed by the factory to perform warranty service, complete mandatory service bulletins where the manufacturer is supplying parts / covering labor, etc.

Aside from manufacturer recommendations there are a lot of other ways to find a maintenance shop that beat simply asking Google and picking one at random.

For the most common single-engine piston aircraft (your typical Piper Cherokee, Cessna 172/182, etc.) you can almost certainly find a mechanic at your local general aviation airport - ask the FBO where you're storing the plane for recommendations or talk to other pilots on the ramp about who they use for maintenance.

For more esoteric aircraft (high-performance singles, twins, vintage/classic/warbirds, etc.) your best resource is often a type club (e.g. The American Bonanza Society for Beechcraft Bonanzas, or ICS for the Piper Comanche) - Google can help you track down a type club, and the members can help you find mechanics who have experience working on your particular airplane.
Type clubs are also a great source of other information (like where to find parts).


During an LPV or GLS final approach, can the extension of the aircraft's cross-section line intersect with the Y or X OCS surfaces? I am studying Obstacle Clearance Surface construction using FAA's Performance Base Navigation manual 8260.58B as my guide. I am confused about the rules concerning aircraft's permitted altitude in relation to the OCS slope and the OCS 3D surfaces.
On page 79, a sample image for LPV/GLS final approach case is provided.

This is a 3D surface, for which the manual states:

3-4-4. Obstacle clearance surface. The primary area OCS consists of the W and X surfaces. The Y surface is an early missed approach transitional surface. The W surface slopes longitudinally along the final approach track, and is level perpendicular to track. The X and Y surfaces slope upward from the edge of the W surface perpendicular to the final approach track [see figure 3-4-3]. Obstacles located in the X and Y surfaces are adjusted in height to account for perpendicular surface rise and evaluated under the W surface.

Based on some calculations I made, from the pilot's point of view the aircraft's cross section seems to intersect with the Y OCS, even if the aircraft's theoretical position is not (it is always above the W surface since it is required by the OCS + ROC slope).
In other words, I would like to know whether the first case (please see left image below) is correct or it should always be like the second case (right image below).

Could someone point me in the right direction?
UPDATE
Since I have found some relevant information in ICAO's 8168 Volume I document, I would like to quote the passage below from Chapter 1:

1.3 AREAS
1.3.1 Where track guidance is provided in the design of a procedure, each segment comprises a specified volume
of airspace, the vertical cross-section of which is an area located symmetrically about the centre line of each segment.
The vertical cross-section of each segment is divided into primary and secondary areas. Full obstacle clearances are
applied over the primary areas reducing to zero at the outer edges of the secondary areas (see Figure I-2-1-2).
1.3.2 On straight segments, the width of the primary area at any given point is equal to one-half of the total width.
The width of each secondary area is equal to one-quarter of the total width.
1.3.3 Where no track guidance is provided during a turn specified by the procedure, the total width of the area is
considered primary area.
1.3.4 The minimum obstacle clearance (MOC) is provided for the whole width of the primary area. In the
secondary area, MOC is provided at the inner edges reducing to zero at the outer edges (see Figure I-2-1-2).

The above figure depicts the assumed lowest flight path in such a way that the cross-section does not intersect with secondary area's OCS surface. However, I am not sure if it is just an example for demonstration, and the aircraft is supposed to be anywhere inside the canyon-like 3D OCS.

The OCS is the edge of the safe flight 'corridor.' It defines a safe volume of airspace for the approach. Since it's normal to have obstacles off to the side of the approach path the OCS typically rises as you move away from the approach centerline.
Your Case 1 is the most correct description of an aircraft flying the approach. The green 'floor' normally will extend greater than one 'dot' on either side of the localizer (or localizer look-alike) and is at least one 'dot' below the glide path. That is the reason a missed approach should be executed if you deviate more than one dot from the approach path. At the zero deviation level for glide path (your blue dashed line in Case 1 assuming the a/c is on path) the intersection with the yellow (x surface) should be beyond the full scale left/right deviation.
Essentially the OCS defines a canyon that you can safely fly through to the runway. So yes, the extension of the aircraft's cross section line can intersect the x and y surfaces, but the aircraft itself should not.


Was the Airbus A300/A310 ever supplied with a yoke and not a sidestick? In the Air Crash Investigation episode "Kid In The Cockpit," which details the crash of Aeroflot Flight 593, the video shows the plane had a yoke not a sidestick

I was under the impression all Airbus models, even the earlier ones, used a sidestick.

Can anybody clarify this for me?

The sidestick was a design that came about along with the new fly-by-wire technology of the A320 in the late 1980's. The physical leverage of a yoke was no longer needed for flight control cables. The older designs of the A300 and A310 series planes from the 70's and 80's have conventional yoke flight controls.

I would not be surprised to see inaccuracies in TV reenactments, but the yoke did happen to be important in that particular case.


Is there research suggesting that VFR cruise altitude rules improve safety? In the United States, 14 CFR 91.159 prescribes cruising altitudes for level flight under VFR:

  (a) When operating below 18,000 feet MSL and

  (1) On a magnetic course of zero degrees through 179 degrees, any odd thousand foot MSL altitude + 500 feet (such as 3,500, 5,500, or 7,500); or
  (2) On a magnetic course of 180 degrees through 359 degrees, any even thousand foot MSL altitude + 500 feet (such as 4,500, 6,500, or 8,500).

In other words, planes going generally east use one set of altitudes, and planes going generally west use another set of altitudes.

Now, it's not obvious that these rules are the best possible rules for VFR cruising altitudes. Some alternatives would be:

No cruising altitude rules at all. All VFR flights select a cruising altitude arbitrarily.
VFR cruising altitudes are given as blocks instead of single altitudes. For example, planes going generally east cruise at 3,200 through 3,800, or 5,200 through 5,800, and so on.
Cruising altitudes are prescribed in such a way that aircraft with different courses are always given different cruise altitudes. For example, require aircraft to cruise at an altitude such that the 100-foot needle on the altimeter points in the same direction as the "N" on the heading indicator.

The Wikipedia article "Navigation paradox" mentions a couple of papers which state that random cruising altitudes would result in fewer mid-air collisions than the VFR cruising altitudes prescribed by regulations.

Is there any research suggesting that the current VFR cruise altitude rules do, in fact, improve safety? In other words, are there any studies which compare the current rules to at least one alternative, and show that the current rules are better?

(The specific rules I mentioned are the US FAA regulations, but I'm also interested in research about other countries' VFR cruise altitude rules.)

Searching Scopus for (VFR OR 'Visual Flight Rules') AND safety in title/abstract/keywords yields two publications (out of 99 hits) that might contain information (or references to other sources) on the safety performance of the current VFR system with alternatives.

Prinzel et al. (2011) - Flight deck interval management and delegated separation for equivalent visual operations

  An emerging Next Generation Air Transportation System concept Equivalent Visual Operations (EVO) can be achieved using an electronic means to provide sufficient visibility of the external world and other required flight references on flight deck displays that enable the safety, operational tempos, and visual flight rules (VFR)-like procedures for all weather conditions. Synthetic and enhanced flight vision system technologies are critical enabling technologies to EVO. Current research evaluated concepts for flight deck-based interval management (FIM) operations, integrated with Synthetic Vision and Enhanced Vision flight-deck displays and technologies. One concept involves delegated flight deck-based separation, in which the flight crews were paired with another aircraft and responsible for spacing and maintaining separation from the paired aircraft, termed, "equivalent visual separation." The operation required the flight crews to acquire and maintain an "equivalent visual contact" as well as to conduct manual landings in low-visibility conditions. The paper describes results that evaluated the concept of EVO delegated separation, including an off-nominal scenario in which the lead aircraft was not able to conform to the assigned spacing resulting in a loss of separation.

Quinby (1980) - General aviation operating requirements for the 1980's

  This paper presents a review of the use of the airspace and the air traffic control system. Safety, capacity and efficiency of this use under Visual Flight Rules (VFR) are compared with the evolving constraints imposed by operations under Instrument Flight Rules (IFR). The concept of Electronic Flight Rules (EFR) as developed by Topic Group III on Freedom of Airspace in the FAA’s 1978–79 E & D Initiatives Process is reviewed. The potential for conservation of air traffic control manpower and aircraft fuel is further developed. Promising areas for further technical exploration are noted. The paper concludes with some considerations for co-existence of VFR, IFR, and EFR traffic during a transition period.


How do the airlines allot the passengers seats to make sure the balance is maintained? How do the airlines allot the seats for the passengers?
Is there any procedure, like first front seats has to be filled next middle and at last the end seats?

Any algorithm works during the ticket booking to distribute the passengers according to their weight?

It depends on the specific limitations of the aircraft and the flight booking load. If the flight is full, it not really an issue. Typically the check-in system will automatically distribute passengers throughout the cabin, starting from the front and moving backwards. Load planners may block rows during check-in if the flight is so empty the center of gravity will be exceeded, unless passengers sit in certain sections of the aircraft.


Can anyone identify this jet? I took the picture in 2011 at McCarran.

It's an F-18 Hornet:

Source: Wikipedia

Here is a view a little closer to your angle:

Source: Wikipedia

The one in your picture has extended range fuel tanks under the wings, the one above shows the hardpoint mounting for those fuel tanks.


What causes Mach No. to increase with altitude at a constant cost index? If a jet aircraft flies at a constant cost index but changes flight level the Mach no required by the FMC will increase with increasing altitude and decrease with decreasing altitude. Why is this? (Disregard aircraft weight changes due to fuel burn etc)

Cost index is a function of Time Cost/Fuel Cost and is more related to True Air Speed than Mach Speed since Mach Speed varies with altitude.

At FL300 M.85 equals 501 knots but at FL400 M.85 is only 487 knots. In order to maintain 501 knots at FL400 you need to increase your Mach speed to M.87


Can I fly a quadcopter over 50m above a property I don't own according to the UK's Dronecode? I have a question about the law on flying quadcopters equipped with a camera in the UK. The dronesafe.uk website states that drones are not to be flown within 50m of any property or people that you do not have control over. Does this mean horizontally or both horizontally and vertically? Basically is it legal to fly a quadcopter above a property that I do not own as long as it is 50m or above the property?

Take a look at page 2 of the "Dronecode". The illustration makes it quite obvious that the 50 metres refers to both vertical and horizontal distance:


Is it possible to take checkride past AFSP training request expiration? My AFSP training request expires next week. Can I do my instrument checkride past that date?

Technically checkride is not flight training (all of my training is complete at this point), so it's not clear to me if I can do it or not.

As far as I can tell (and from my own experience), you don't need any TSA approval for a checkride.

Looking at the regulations, 49 CFR 1552.1 defines flight training as "instruction received from a flight school" (including from individual instructors). A checkride isn't instruction, as you said, although I can't find a regulation that explicitly says that (probably because there's no real need for one).

And looking at the FAA's requirements for checkrides:

The FAA's instructions to examiners for an instrument checkride don't mention security or say that they have to check anything related to the TSA or AFSP as part of the preliminaries (see section 5-434, Establishing Eligibility and 5-446, Procedures)
There's no mention of the TSA either in 61-65F - Certification: Pilots and Flight and Ground Instructors (apart from some notes on verifying identity)

There's also nothing in the IACRA process about the TSA or security either, which makes sense because that should match the checkride eligibility instructions.

My own experience is also that it isn't relevant to the checkride. I've done two instrument checkrides after getting the TSA's approval for training and neither DE asked me for any information about the TSA or AFSP, they were only interested in my logbook (and medical etc.). I suppose there could have been some extra check behind the scenes or in IACRA that I wasn't aware of (and my TSA approvals were still valid) but I doubt that was the case.

Finally, I realize that all this still doesn't give a positive confirmation that it's allowed, so if you want to have that I suggest you call the AFSP hotline and/or your local FSDO to get a definite statement.


What is the Boeing 727 AC Generator Panel Part Number? Does anyone know the part number for the Boeing 727 AC Generator Drive panel?  I have searched the Internet and have not found the part number.

(Source)

The part number is 69-17528-XX, where XX (the dash number) varies based on customer preferences and when the aircraft was produced. Without knowing specifically about the particular airplane the module came from, there is no way to know the part's dash number without physically examining it. See the image below from a search of Icon Aerospace's capability list. Directly searching the capabilities lists of FAA/EASA-licensed repair stations usually yields more reliable results than searching parts "aggregator" or "locator" sites. For example, this list links the part number specifically to a 727.


How do I calculate the impact of the winds aloft in this test question? I was flying through this section in the ASA test prep book, I thought I had mastered this E6B.  But this has me stumped:

I can’t do the math to figure out how many knots I’ve traveled. But in the answer it has me plotting a course of 280 (100 + 180) from the departure point. I cannot figure out for the life of me where they got this course.
I see that the winds are from 100 in the winds aloft, but I can’t imagine how I get a 100+180 course from that.  I feel like I’ve missed some major concept.

First of all, make sure you’re only doing the questions that will actually be on the test you’re taking. This specific question is only for the LSL question bank, so unless that’s what you need, forget it and move on.
In a balloon, you will be carried by the winds aloft. If the wind is from 100@8, then your track will be to 280@8.
First, use your protractor to draw a track line on a track of 280 from the point of departure. This shows your balloon’s track over the ground.
Next, multiply 8 by the (decimal) number of hours you will be in the air, and then use your scale to mark that distance along the track line. That’s how far your balloon will have traveled at the specified time.
No need for an E6B here.


How are squawk codes assigned? How are the 4-digit squawk codes assigned to individual flights?

This answer indicates that there should be a "correct" one. How does ATC know what is "correct" and what is "incorrect"?

To start out with, I'll be referring to how the US does it, and it's generally laid out in the National Beacon Code Allocation Plan. Every facility has various blocks of codes that they can use to assign to flight plans, as described in the linked document. For example, a smaller tower/approach control, could use the codes 0101-0177 for IFR flights that are only in their airspace, and 0201-0277 for the VFR flights that stay in their airspace, and a Center would have a similar bank of codes for flights just in their airspace, and then a different bank for codes that go to different centers. The whole purpose to these allocations, is to minimize the need to change the squawk code while in the air, and to avoid overlap with adjacent facilities.

As flight plans are submitted to the various computers, about 30 min before an Instrument flight plan's proposed time, it's officially assigned a code from the available blocks, and it's printed at the departure airport or facility that'll first work it. Flight plans stay in the system, depending on however long the center sets. Often it's 2 hours, sometimes 3, but during bad whether when lots of flights are being delayed, it could be extended to 4+ hours. The drop interval helps to keep enough codes available for aircraft intending to depart, while allowing flight plans to go away if something happens and the flight won't be departing.

If the aircraft just randomly calls ATC, the controller types it in to either the radar or flight plan system, depending on what extent the pilot wants services, and then the system prints out an appropriate beacon code.


Do I need a license to flight test a homebuilt seaplane at very low altitude? I am asking this because me and my friends are building a homemade seaplane or boat whatever you want to call it. It's not designed for long-range or high-altitude flights. We're not going to fly at a typical altitude of normal planes/seaplanes but we're just flying it to test it. Do we require a license to fly it?

This is in Canada and it's a manned aircraft.

14 CFR §1.1 defines an aircraft as “means a device that is used or intended to be used for flight in the air.”  Flying boats are intended for flight in the air.  Therefore.....