Under what legal standing can after-hours ground access to an airplane be forbidden? (USA-specific only) This came up when a friend was unable to access his airplane because the security guard refused to open the gate. It was a mountain flight in a small plane, and so a timely departure was urgent for safety. The security guard didn't have a reason not to let the pilot access his plane, he simply felt he didn't have the authority to make that decision.
In the end, he was only delayed 45 minutes and didn't miss his weather window. But after I heard the story, it got me thinking what we should do when confronted with this situation, especially if the delay will cause severe consequences (missing a weather window, for instance).
In the US, under what normal conditions can a pilot be forbidden access to her/his plane, and what are the legal justifications for that? I have flown out of the obnoxious KBED and so am familiar with heavy-handed escorts, but this is different from arriving after-hours and being simply prevented from accessing your airplane. That would seem to run afoul of rules about private property, esp. since the tie-down is freely accessible if you fly in.
Generally, as a pilot I have always understood that I have the right to access any public airport for normal flight activities, baring some kind of NOTAM or other abnormal situation.
Are GA airports typically accessible 24/7? somewhat touches upon this subject, but it isn't well documented that these are "private (or state-owned) businesses". Indeed, airplanes and public airports are regulated by the FAA, and as such probably fall under all kinds of interstate commerce laws.

As per my answer here the FAA does define "Public Airport" but does not specify that ground access must always be available. The answer mentioned in the question, you link here covers the general scenarios where issues could crop up:

Private Airports: Are generally free to make rules as they see fit and could potentially prevent you from entering the property even if the tie down they offer is free. There are lots private airports in the US and there are even some big airports that are privately owned. Private airports while conforming to certain federal aviation regulations may ultimately be built on private land which falls under different (often local) regulations.
Ports Of Entry: An airport that has customs facilities may prevent you from accessing your aircraft prior to clearing customs or if they have another reason not to let you onto the ramp. This can get tricky as its often administered by the TSA.
Local Regulations: Airports are often owned by local governments or port authorities there is nothing preventing them (as far as i know) from making a rule/regulation that prevented field access at certain times.

The most frustrating issue in my experience is the "Private FBO" problem. Often times airports are publicly owned but physical ramp access is handled by Private FBO's that may chose to not be open 24/7 or may (what sounds like in your case) station a clueless guard at the gate after hours. This creates more of a practical issue than a regulatory one, either the owning authority needs to mandate the FBO allow people onto the ramp at all hours or the FBO needs to step up their game a bit when it comes to educating their employees.
I'd say 8/10 times the gate code is the CTAF frequency...


When must we make contact with ATC? If I, pilot, have to make a stop at the undesignated parking position for some reason, such as FOD or ground handlers crossing in the ramp area, it is mandated that I have to contact ATC to explain why I have to stop?

Is there any global reference that describing when flight crews have to make a contact with ATC?

Is there any global reference describing when flight crews have to make contact with ATC?

On the ground, you need a clearance from ATC when you are on the maneuvering area, which consists of taxiways and runways. The ramp/apron is typically not part of the maneuvering area, and as such not controlled by ATC, although many large airports have some sort of ground control for these area.

In the air, you need a clearance from ATC whenever you are in controlled airspace. Some countries additionally require pilots flying IFR to be in contact with ATC even in uncontrolled airspace.

Note: ‘controlled airspace’ means an airspace of defined dimensions within which air traffic control service is provided in accordance with the airspace classification; (from SERA, EU 923/2012)


Is there an official English version of LTF-UL? I have found the German version of the ultralight regulations under Germany airworthiness authority, but I have not found a link for English version of that. is there any?

For LTF-UL 2019 there is no official English translation, unlike, say, documents from the United Nations or the Vatican.  German aviation forums have plenty of statements like

Ja eine offizielle englische Übersetzung gibt es tatsächlich nicht

But the document's language is technical and precise enough that Google Translate can manage it accurately.  Here is the translation, as .txt (as HTML, something weird happened).  http://camille-g.com/tmp/LTF-UL-english.txt


How does the IAS stall speed vary with increasing altitude? First of all, we all know what IAS is and if not for some people you can follow this link to read the basics about stall and the differents speeds. So we also know that our TAS/ Mach number will increase with increasing altitude.

Let's assume that our IAS stall speed is 100kts at sea level, what will be our IAS stall speed at 30 000 feet with exactly the same aircraft ? (Assume ISA atmosphere)

Everyone would be tempted to answer that it doesn't change, right? but what about the low speed buffet in this picture ?

We agree in saying that the low speed buffet here is not the same as the one at sea level but look, our IAS/CAS stall speed has a higher value now. Maybe that it's a representative value of IAS/CAS calculated by the Air Data Computer from an EAS but still, our IAS stall speed has rised.

We can also keep it simple and think about it for a non pressurized single engine aircraft. I don't need an exact value but I would love to have a logic and smart answer.

It seems to be very basic but when we correctly think about it we can find ourself a little bit confused.

For me, the answer is : The IAS stall speed will increases

Airplanes do not stall at the same indicated speed or even at the same angle of attack - it all depends on circumstances.

The angle of attack dependency is discussed here. An increased pitch rate can push the stall angle of attack 50% higher than what the stall angle of attack is in stationary conditions.

The next big factor is the Mach number. When increasing the angle of attack, the flow around the airfoil's nose will develop a suction peak. This suction is equivalent to higher local speed, and if the critical speed (when local flow speed equals the local speed of sound) is exceeded, the flow past the suction peak will no longer behave similarly to the flow at the same angle of attack but a lower flight Mach number. Let's just say that the local Mach number in the suction peak has a strong influence on the stall angle of attack, and flying at a higher Mach number lowers the stall angle of attack, sometimes dramatically.

Increasing altitude will raise the flight Mach number in two ways:

The reducing density means you need to speed up to fly at the same dynamic pressure, and
the atmospheric lapse rate decreases the speed of sound in air.

Both effects conspire to reduce the stall angle of attack at 30.000 ft to a value quite a bit below that at sea level. Details depend on the airfoil and specifically on its nose radius and wing loading.

Only very light aircraft will not be affected by the change in Mach number, but even here the stall angle of attack at altitude is lower than at sea level due to the reduction of the flow's Reynolds number with increasing altitude.

In short, the indicated stall speed goes up with increasing altitude for a variety of reasons and does so nonlinearly. The magnitude of the change depends on a multitude of details.


Is there a minimum weight requirement for flying manned aircraft in controlled airspace (B, C, D, E)? The Colomban Cri-Cri is a small twin engine plane with an empty weight of ~200 lbs and a MTOW of ~400 lbs.

Can I fly this in controlled airspace? What are the requirements for aircraft registration?

If there were any minimum weight requirement for manned aircraft in controlled airspace, the requirement would probably be in 14 CFR Part 91, Section 126 through Section 135. These are the sections which describe the operating rules for various types of airspace. I looked through those sections, and there are no weight requirements.

I also can't imagine why there would be a minimum weight requirement for any class of airspace.

Like most aircraft, the Colomban Cri-Cri must have an airworthiness certificate and a registration certificate (14 CFR 91.203). The regulations describing getting an airworthiness certificate are in 14 CFR 21, Subpart H.

Some aircraft weighing less than about 254 pounds are "Part 103 ultralights" and do not need to be registered. However, this doesn't apply to the Colomban Cri-Cri, because Wikipedia says that it has a cruise speed of 100 knots; Part 103 ultralights must be "not capable of more than 55 knots calibrated airspeed at full power in level flight".


What are the tube shaped structures on the back of the fuselage of this 737? A previous question asked what the little metal plates between the horizontal and vertical stabilizer were (they are vortex generators), however I am much more interested in what the gray tube shaped structures are that go down the top quarter of the fuselage. What are they and what do they do? Are they sensors, countermeasure pods, something else?

The aircraft is the Indonesian Airforce Boeing 737-2X9 “Surveiller” aircraft, used for Maritime Patrol. The fairings house Side looking Airborne Radar for matitime surveillance. From b737.org:

  Fitted with Motorola AN/APS-135(V) Side Looking Airborne Modular Multi-Mission Radar (SLAMMR) The antenna of which was mounted in two 16ft housings on the upper rear fuselage. This system could spot small ships at ranges of 100nm.

Indonesia Operates three of them- AI-7301, AI-7302 and AI-7303.


How many kilowatts to get an electric 747-8 airborne? Reading about the Airbus E-Fan and it's dual 30 kW thrust fans caused me to wonder: assuming the need for four electric fans, how many kilowatts would be required to power each fan with enough thrust to get a Boeing 747-8 airborne?

First, let's figure out how much power a 747 needs to takeoff:

Assume:

Engine thrust = 284 kN
Takeoff speed = 170 knots
Takeoff power = 90% max power

Using $P=Fv$, converting the variables to SI units, we get
$$Power=88,948,800 W$$

Or, in other words, around $90MW$.

EDIT: This calculation is only correct if the engine efficiency is 100%, because it is based on work done. For a realistic estimation, see Jan Hudec's answer. I'll leave the rest of this answer based on 90MW as I'm too lazy to update the numbers.

But just exactly how much is 90 megawatts?

An average laptop computer consumes 20W on daily use. You can power 4.44 million laptops with this power.

A high-end desktop consumes 300W under heavy load. You can power 300,000 desktop computers. If you stack 20 of them in a server tower and put 100 towers on each floor, you need a data center with 150 floors to fit those machines in.

Let us take this a step further and evaluate the total energy needed for a flight. Assume all required energy comes from onboard energy storage (i.e. no solar panels / windmills). Let's also assume a full power climb to cruise altitude of 15 minutes, 50% power cruise for 4 hours, and a completely idle descent which does not consume any power at all.

Using $E=\int P dt$, we get the total energy needed for a flight is $$720,485,280,000 J$$

With that amount of energy, you can pull a 735 kiloton object up 100m. If all those weights are water, that's close to 300 Olympic swimming pools.

If you power the whole plane with batteries, you'd need 47 million AA batteries.

Of course, if you manage to get 14 of these electrical 747s together, you can generate 1.21 gigawatts and get Back to the Future.


Can a 777X legally be ferried with one or both wingtips folded? The 777X family (777-8/-9/-10) features wingtips that fold up on the ground to let the aircraft fit in tight spaces. These have to be extended and locked in place before a revenue flight can take place, but can a 777X legally be ferried with one or both wingtips in the folded position - for instance, if one of the wingtips is jammed in the up position while at some backcountry airport that doesn't have maintenance facilities for a 777?

For the purposes of this question, I'm assuming that it's physically possible to operate the aircraft. The non-folding part is the same length as the wing of a regular 777, so it would still be able to take off safely, just with considerable performance penalties compared to normal, wingtips-folded-down flight. Ferry flights for maintenance purposes can get away with a lot that wouldn't be allowed during line operations (for instance, multi-engine jetliners can be ferried with one engine - or, for quadjets, two - inoperative, and the 747-400 can be ferried with one of its winglets broken off).

As Ron notes in the comments to another answer this is a perfect situation for a Ferry Permit/Special Flight Permit. The FAA via your local FSDO can authorize aircraft to fly for the purpose of being fixed elsewhere via a ferry permit. This question covers whats needed for that.

However in some cases it may be cheaper to fly (or drive) in a maintenance team and fix it on site. Moving an empty 777 even short distances means burning quite a bit of Jet-A. For the cost of the reposition it may just be cheaper to send a team (possibly in car) with the parts and tools they need to get the job done.

On a similar note its likely that the majority of fields big enough for a 777 to touch down have at least some form of maintenance on hand. Again it may be cheaper for an airline to contract the job to a local shop than bother with the ferry logistics and costs.

Boeing also offers these services if you should need them in a pinch as part of the AOG services.

  Our technical experts will provide on-site, comprehensive and
  integrated assistance to recover an airplane. Our goal is to quickly
  and safely return airplanes to service, using methods and procedures
  that avoid costly secondary damage.

From what I can tell they will basically show up with parts and people to get the plane back in the air just about anywhere you can fly it out of.


Why do flaperons 'move down then up' on takeoff roll on a 787? The flaperons on the 787 go through certain motions once the TO/GA is pressed. I've always seen it when the 787 is viewed from behind on takeoff. The motions are completely symmetrical, i.e., not related to pilot inputs.

Video example 1
Video example 2

I'm wondering why they're programmed to do that. The primary flight computers (PFC's) go through a complete self-check after every flight. Testing the ranges of motion is done by the crew after engine start-up. Seems like the wrong time to run a test.

The drooped outer ailerons do not go through a similar 'check'. My thoughts: calibration for their position, or drag reduction during initial roll. The latter would not explain the full down deployment though.

The frames below are from an on board video for a clearer image:

1) Taxi
2) TO/GA
3) Slowly full up
4) Back to normal.

I found this 16-year old thread on airliners.net. The Boeing 777 has the same system, and at the time it was unique in that. (You can watch it here.)

When takeoff power is applied, hydraulic power is removed from the flaperons, as not to stress the actuators for an extended duration, which causes them to drop due to gravity. They are then slowly lifted by the rushing air. At around 100 knots, power is restored to them.

The stress being avoided is from the engine's jet blast. During ground runs for an engine, the flaperon is known to flutter.

The poster cites the B777 Maintenance Training Manual Rev 4 02/08/1997. The reasoning comes from this other 12-year old thread.


How feasible is it to use Smart Materials on aircraft? Smart or Shape-memory materials have been known for quite long. What factors/limitations are put on it for applications in aircraft?

For someone who doesn't know much about its material properties, it seems quite good to have deforming wing or other parts and seem to improve aircraft performance. (One example might be: suitable wing geometry deformation according to aircraft's speed regime)

Shape-memory alloys are only a small part of smart materials. Once deformed, they will change back to their old shape when heated or subjected to strong magnetic fields. Of the many alloys with this characteristic, only a few like nickel-titanium would be suitable for primary structures. They are extremely expensive to make and to process, so they have never been an economical alternative.

Also, heating and cooling would be required to switch between shapes, which is very energy intensive when the outer structure of an aircraft is involved. Airflow will ensure intense convective heat transfer, and to maintain the needed temperature will be very uneconomical. Please consider that an aircraft with shape-memory alloys would need to carry extra fuel for heating or cooling over much of the flight time. Hinges and electric or hydraulic actuators will have a clear mass advantage when you consider the system mass, including energy sources.

I guess you agree that creating strong magentical fields in parts of an aircraft is an exceedingly bad idea, so I will rule out magnetic shape-memory alloys.

Shape-memory alloys will only switch between two shapes, and intermediate shapes are easier to realize with hinges and actuators. Sure, a smooth shape is aerodynamically better than one with a contour break at the hinge line, but the small aerodynamic advantage of shape-memory structures is quickly lost when you look at the whole picture.

Another disadvantage is the accumulation of small cracks with every shape change. The low number of cycles will either require frequent replacement of the shape-memory parts or a very limited structural life of the aircraft.

In the end, much of what can be said about other smart materials also applies to shape-memory alloys. Their main function is to justify research grants and to keep the press occupied.


How to interpret/use "Fix Minimums" (at KALB) This one stumped both myself and my CFI. Im specifically asking about the minimums at KALB IL/LOC 19 but a general answer is also appreciated.

The plate lists two distinct sets of minimums and we were confused about the S-LOC 19 minimums. The first set seems like the obvious regular ones and takes you to the labeled step down altitude. Then there is a second set for WESTS FIX MINIMUMS that are lower to the first set.

What is this second of set of minimums for and how can they be utilized?

It seems a bit odd that they reference an altitude below the step altitude. Presumably you fly 820 to 0.7 on the DME, but yet the WESTS FIX MINIMUMS seem to allow for lower than this.

(full plate for reference incase it changes)

The 620 is not at WESTS.

It's been discussed in multiple places, e.g.:

https://mooneyspace.com/topic/19113-ifr-fix-minimums-question-kipj/
https://www.pilotsofamerica.com/community/threads/fix-minimums.28308/

The way to read it is [WESTS FIX] MINIMUMS, and not [WESTS] FIX MINIMUMS, i.e., the 620 is not at WESTS, but the 620 is when you can identify WESTS (having DME on board for the L-DME in your case).

But let's check the AIM (5-4-20):

  When a fix is incorporated in a nonprecision final segment, two sets of minimums may be published: one for the pilot that is able to identify the fix, and a second for the pilot that cannot.

Another reason could be:

  Two sets of minimums may also be published when a second altimeter source is used in the procedure.

An example for that would be the KIPJ ILS Y or LOC Y RWY 23.

Of course when in doubt, contact the FSDO.


In the B737NG, is the CTR tank fuel the first to be pumped when there is fuel in all tanks? In a B737NG, assuming you have fuel in all tanks, Wings and Center, and that all pump switches are ON, will the fuel from the CTR tank be the first to be pumped, despite all Fuel pump switches being in the ON position?
Will this happen even if the CTR fuel pumps are OFF and only the Wing Fuel pumps are ON?
And why are there so many warning in the FCOM about pumping the CTR tanks and warnings about not doing so in climb or descent if under 1000 lbs of fuel in the tank?
I have already read the "Why are fuel tanks in the wings filled first, and why are they used last?" post and answers.

Because the center pumps effectively put out more pressure, the fuel from that tank will be used first when all pumps are on.


How many of this aircraft were manufactured? What was the total quantity issued of this model aircraft (including any modifications).

The aircraft looks like the Convair CV 440 Metropolitan (maybe CV 340) a variant of the CV 240, in operation with the KLM. According to Wikipedia, a total of 1181 of all the variants were built.


What are these windows/portholes on the English Electric Canberra bomber? This may be an obvious question, but I don't know, which is why I'm asking here. I've searched "Canberra canopy porthole" and "window", but didn't get any information. There is a porthole of sorts on the left side of the canopy of this bomber, I'm wondering what it's for.

Photo source.

Here is a view from inside the cockpit:

Photo source.

There also appears to be a similar thing on the bottom of the nose of the aircraft, offset to its right. The following is a screenshot from a video game, as I wasn't to find a photo of this.

I'm tempted to say that this second one is to do with bomb sighting, however if it weren't there, the bomber would have just as good a view, wouldn't they?

It's called a "Direct Vision" (DV) window. The canopies are sealed shut, so the small DV window is provided as a way to open a small hole if required. For example, to communicate on the ground or in the event of icing or other canopy issues.

Edit: I wasn't able to find a formal source, but this page is fairly authoritative:

http://alverstokeaviation.blogspot.com/2016/08/english-electric-canberra-technical-tour.html


How does the heading selector on the ADF work? How does the ADF indicator work in terms of pointing the needle in the direction of the NDB signal? I understand that the ADF needle points towards the direction of the NDB signal for a given frequency, but when a pilot tunes in the ADF signal, the heading ring does not change when the ADF was tuned into the frequency, only the direction of arrow changes.
So my question is, how do you use the heading selector when navigating with the ADF? And is it important to change the heading?

In the image, let's assume the aircraft is heading 030 degrees, but the heading on the ADF does not change to 030 degrees only the ADF needle changes its direction. Why is this?
If I were to turn from 030 degrees to 180 degrees, the needle would only change its direction not the heading of the ADF.

It's just a manual compass card (or some call it a heading ring), not an "omnidirectional bearing".  The ADF needle just points to the station (NDB or AM radio station) relative to the airplane; that's it that's all.  If the needle's at 9 o'clock, the station is off your left wing.  The compass card is just a reference device to provide a mental shortcut for determining the magnetic compass bearing of the station relative to the airplane when you are flying a particular heading.
To use, you set the compass card to the heading you are currently flying, and this gives you a quick way to see the compass direction of the ADF station relative to the airplane.  Ideally, you would want the compass card slaved to a gyrocompass system so it shows your heading directly and fancier systems (RMIs) do that, but a standalone ADF doesn't have that feature so you have to set it yourself.
The NDB in the picture is 60 degrees off the nose of the plane. You're flying a heading of 030 and want to know the actual compass direction from the plane's current position to the NDB; in other words, the compass heading to fly to proceed direct to the NDB.
You could just subtract 60 from 30 to get 330 as the bearing to the station, but instead of having to do that little bit of mental math, you dial the compass card to 030 and there's the needle pointing at 330.  Of course, the card is just fixed where you set it, so you have to make sure your actual heading matches the card setting at the time you check the reading.


Efficiency of Flyboard engine From what I understand (not much), you need good specific impulse to travel long distances with, say, flyboard.

I know that RP1 has good specific impulse. I wonder if he used it, and what type of oxidizer/propellant would be most efficient for this task, and feasible (very small engine, not that high temp) .

To be specific: The question is if the efficiency (in terms of travel distance per unit mass of fuel) could be improved by choosing another type of engine/fuel?

I'm not directly familiar with the engines Zapata uses on the Flyboard Air, but I'd hope they're using a kerosene derivative like JP-1 or commercial Jet-A.  Alternatives (gasoline, diesel, various alcohols) have no better energy content per volume, and some (alcohols) considerably less.

There is no case (for low altitude atmospheric flight) in which a rocket can beat an air-breathing jet for specific impulse/specific fuel consumption -- because of the need to carry oxidizer, instead of just using the air for that purpose, the amount of fuel/oxidizer available is limited by tankage.  This is why airliners, warplanes, and private business aircraft use jets or turbine driven propeller engines instead of rockets (not to mention the far higher durability of a turbine compared to a rocket engine).


While waiting for a delayed outbound flight how can I guess where's the inbound plane? This summer in Mykonos our flight back to FCO was delayed and nobody at the airport could communicate reliable estimates on when it would be.

In that case I managed to find the FCO-JMK inbound flight on FR24 and saw it left FCO with 2 hours delay, so our own would have been at least that.

In bigger airports with more connections you might not be able to guess which airplane will become yours.

I guess the registration number of the plane assigned to my flight will be available some time (maybe a few hours?) before as per the flight plan.

Is there a reliable public accessible source for that?

When I have the assigned RegNum I can use plane finder, FR24 or whatever to see if it's on its way and have a rough estimate of when it will land and then be available for my flight.

Apologies for my English.

Thank you

It's difficult to find out what the inbound aircraft is, unless you are at a small airport and/or the airline you are flying on is only operating a few routes from the airport. When you are at a big airport and/or the airline is operating many routes there, you have no way of telling where your aircraft is. For smaller airports, you can effectively find the inbound aircraft by using the appropriate filters in FR24.

Note that in some cases the aircraft planned for a flight can be changed last minute. This typically happens when aircraft are significantly delayed inbound to their hub / main base and the airline decides to minimise the outbound delay costs by assiging a different aircraft.


Is there an API to get real-time FAA flight data? I have been using an Android app to track flights. Their information is pulled from their own proprietary database, and some (with 5 minute delay) from the FAA.

I was thinking about making an app that would do this as well by pulling from multiple data sources.

What are some good APIs, either paid or free, that gives you near realtime data of flying aircraft?

You can't get real-time data from the FAA without an operational need, and organizations which do receive real-time data cannot legally re-distribute this data publicly, except to other organizations approved by the FAA. An operational need pretty much means you have to be a flight dispatcher for an airline or commercial operator, not just have an interest in tracking flights.

You can get some real-time data from your local area using an ADS-B receiver. See this  question for more information: Where can I find real-time flight tracking with the least amount of delay?.

If you are okay with the five minute delay, then flightaware has an API you might consider. The direct feed from the FAA is called Aircraft Situation Display to Industry (ASDI) and I believe you can apply for the delayed feed, though I've never gone through the process, and the government's site is very sparse in information. I would suggest contacting them before attempting to apply if it's something you're interested in.


For designing a runway, what are the largest cargo airplanes in use? I am working on a project where I have to design a runway for large cargo planes and I need to know what kind of planes I should assume would land there.

Size doesn't matter.*
If you are designing a runway, then you should get familiar with ACN and PCN.

The aircraft classification number (ACN) is a number expressing the relative effect of an aircraft on the runway pavement for a specified standard subgrade category.

* There can be the largest aircraft out there, but it may have a lot of tires, so the force it will exert [per tire] on the pavement might be lower than that of a smaller plane (e.g., A380 and MD-11).
From the linked Wikipedia article, the MD-11 stands out as the harshest on pavements (after discounting non-freighter aircraft).

Runway length, and wingspan
In most cases, aircraft are loaded according to the available length, not the other way around. Not all airports that handle 747s have 11,000-foot [corrected length] runways.
For the wingspan (or main gear span), the categories are defined by ICAO Aerodrome Reference Code.

Element 2 of the Code is derived from the most restrictive of either the aircraft wingspan or the aircraft outer main gear wheel span.


Why can't the 737 MAX's horizontal stabilizer autotrim be cut out by control yoke inputs? According to this article, a horizontal stabilizer runaway on the 737 MAX, unlike with all other 737s, cannot be countered with yoke inputs:

Older 737s had another way of addressing certain problems with the stabilizers: Pulling back on the yoke, or control column, one of which sits immediately in front of both the captain and the first officer, would cut off electronic control of the stabilizers, allowing the pilots to control them manually.
That feature was disabled on the Max when M.C.A.S. was activated — another change that pilots were unlikely to have been aware of. After the crash, Boeing told airlines that when M.C.A.S. is activated, as it appeared to have been on the Lion Air flight, pulling back on the control column will not stop so-called stabilizer runaway.

Why would the addition of MCAS require removing the yoke trim override mechanism?  In the event of a trim runaway, the pilots' first reaction is going to be to pull (or push, depending on the direction of the runaway) the yoke, and requiring them to perform a separate, different action in the heat of the moment to disable the autotrim mechanism is an unrealistic expectation; allowing yoke inputs to cut out the autotrim relieves the pilots of the burden of having to recognise the problem as a trim runaway in order to solve it, and allows the problem to be solved in the same manner as other unwanted pitch excursions (by pushing and/or pulling on the yoke(s)).

Allow me to emphasize the article quote differently:

  That feature was disabled on the Max when M.C.A.S. was activated

For a regular trim runaway without MCAS activation, the yoke can still cut out electronic trim as before. The only change was inhibiting this behavior when MCAS is active. MCAS is designed to improve handling at high angles of attack. One way to get to a high angle of attack is with lot of yoke input, so it would somewhat defeat the purpose to stop MCAS in that situation.

The designers chose to trust MCAS (and its sensor inputs) over the pilot inputs in this situation. It certainly seems now that this trust was misplaced, but this has more to do with the system design than the general philosophy. Fly-by-wire planes have many protections that will change control input depending on sensor inputs. In normal law, Airbus alpha protection will prevent the angle of attack from increasing, even with full aft sidestick input. It compares three sensor inputs to do this, rather than trusting only one, but even that is not infallible.


Why is jet fuel cheaper than piston fuel? Why is Jet-A cheaper than 100LL? Shouldn't it be the other way around?

Jet-A (and all turbine fuels) are far cheaper than 100LL (at least in bulk; retail prices vary due to local supply and demand as well as different regional tax regimes on aviation fuel) for several reasons.

Scale

Southwest Airlines alone burned through 1.9 billion gallons of Jet-A in 2015, dwarfing the mere 175 million gallons of 100LL that the entire US GA piston fleet consumed in the same year.  This means that Jet-A is made and traded in large volumes, enough to merit refiners sometimes optimizing for its production over other products in certain refineries, while avgas is the bastard child of the refining world -- people would rather make other things that are easier to sell than 100LL.

Ease of Production

Jet-A, like all kerosene fraction products, is straightforward to produce: straight-run kerosene that has been run through a few sweetening (impurity removal) processes is mixed with mid-weight distillates from heavy cracking processes (catalytic crackers, hydrocrackers, cokers) and presumably processed further with hydrogen and clay to get rid of more impurities.

On the flip side, there are all of two TEL (tetra-ethyl lead, aka the "lead" in leaded gasoline) producers on this planet that I can find (Innospec in the UK and TDS Chem in China).  Considering that the last few countries that use it in mogas are working on phasing it out, and very few road vehicles sold on the global market these days can even burn it to begin with due to being made to more stringent emissions specs, it'd be safe to say that the majority of TEL made on this planet is going into planes.

Atop that, avgas requires large quantities of high-octane blendstocks, but cannot use any oxygenates (they are prohibited by the avgas spec, aka ASTM D910, as GA fuel systems aren't compatible with 'em, especially ethanol).  These high-octane blendstocks are primarily alkylate and reformate, both of which require specialized refinery equipment to produce.  Furthermore, reformate is an inefficient source of high-octane blendstock (reformate is very heavy in aromatics such as benzene and toluene, which are better off getting distilled out of the stream to be used as a valuable chemical feedstock instead), and alkylation, while an efficient way to produce high-octane blendstocks, requires an acid supply nearby (either sulfuric or hydrofluoric), limiting where alkylation units can go.  Finally, both of these blendstocks are in demand for motor gasoline production as well, which means that most refineries that produce them are filling mogas demand first and avgas demand second.

Handling

Jet-A is relatively easy to handle -- it's a close cousin to the kerosene on hardware-store shelves.  It has a relatively high flashpoint (meaning you need to make a fine mist of it mechanically or heat it aggressively to ignite it), and this low volatility also limits worker exposure to the relatively limited chemical hazards it poses.  Furthermore, it can be shipped readily via most refined-products pipelines without posing unusual hazards or risking excessive cross-contamination by or to other products.

On the other hand, tetra-ethyl lead is highly toxic, and 100LL is toxic not just because of TEL, but because of volatile hydrocarbon toxicity.  While isoparaffins seem to be less problematic than normal paraffins from this standpoint, volatile aromatics (Benzene, Toluene, Ethylbenzene, and Xylene, or BTEX for short) are well known as troublemakers in the human body.

Atop this double handling hazard (volatility of the fuel and toxicity of TEL and light aromatics), pipelining 100LL is a much harder task due to the TEL contaminated transmix (contaminated stuff from the boundaries between products in a multi-product pipeline) it produces.  Normally, transmix is reprocessed by refiners or dedicated transmix reprocessing plants to produce gasoline and diesel (with most of the kerosene fractions in the transmix being lumped in with the diesel for simplicity's sake), but the presence of TEL in transmix renders it unreprocessable as any more than 50mg/gal of lead in motor gasoline means it is contaminated and unsellable as per EPA regulations.  Furthermore, shipping 100LL in a multiproduct pipeline risks contaminating other products with lead batch-wide due to dead legs and other such cross-contamination hazards, which means that in practice, 100LL is never shipped in multiproduct pipelines.

Instead, 100LL is typically railed or barged to terminals, and sometimes even trucked directly from the refinery as not all terminals have rail or barge access.  This drives up shipping costs compared to every other fuel (save for ethanol and other fuel blendstocks that are surfactants).


What solutions are there against deep stalls? What solutions are there against deep stalls?

According to SKYbrary:

  Aircraft with a T-tail design are often configured with a Stick Pusher system to help prevent the mainplane angle of attack from reaching a value that could result in a Deep Stall.

Are there other solutions?

The Airbus A400M military transport was equipped with a rocket engine pointing downward which could produce a 5-second burn during testing of deep stall characteristics. It isn’t standard equipment though.


When flying to a towered airport when the tower is closed, what frequency should I use? The attached picture shows the Rapid City Regional Airport, KRAP.  If I arrive after KRAP's tower is closed, which frequency should I use: 125.85 or 122.95?

You use the CTAF for announcing your position and intentions, i.e. 125.85. From the AIM 4-1-9(g):

  If an airport has a tower and it is temporarily closed, or operated on
  a part-time basis and there is no FSS on the airport or the FSS is
  closed, use the CTAF to self-announce your position or intentions.

4-1-9(b) says:

  The CTAF may be a UNICOM, MULTICOM, FSS, or tower frequency and is
  identified in appropriate aeronautical publications.

125.85 is marked as the CTAF on the sectional and listed in the Chart Supplement.

Note: The letter "C" in the dark circle next to the control tower ("CT") frequency indicates that the CT frequency is the CTAF frequency at that airport.


How would one perform a more thorough preflight of the engine on a single-engine airplane without easy access to engine compartment? On a lot of the Cessna 172 and 182 airplanes I have seen, there isn't an easy way to look at the engine in the engine compartment and see all of the components during a preflight. In fact, usually the only thing you can really do to see the inside of the engine compartment is to peer through the tiny oil/fuel sump door.

The POH for a 1978 Cessna 172N in the Preflight Checklist simply says:

Engine Oil Level -- CHECK

Before first flight of the day and after each refueling, pull out strainer drain knob...

Propeller and Spinner -- CHECK for nicks and security.

...

Carburetor Air Filter -- CHECK for restrictions by dust or other foreign matter.

...

So I know that while it's not a requirement to see the components of the engine and look at the engine compartment, it seems prudent to add something to your preflight that might help give you an indication if you should investigate further before attempting the flight.
How do you more thoroughly preflight the engine of your aircraft when you can't access the engine compartment without completely removing the cowling?

These issues don't pop up that often that you would need to include them on a preflight check. Those aircraft/engines are reliable enough that any issue can usually be determined by things like:

Excessive oil use
Oil Temperature / Pressure Changes
Rough running or improper behavior during run-up

That is why you do a run-up in these aircraft that checks many systems, so you can spot those kinds of issues. But the reality is that even if there is an oil leak or missing safety wire, those issues are reviewed (in detail) and fixed in the annual inspection. The aircraft is reliable enough to not worry about it between inspection intervals. For rental/hire aircraft this inspection happens more often, every 100 hours.

Some of the issues may be caught during oil changes as well, which happens every 50 hours (depending on manufacturer recommendations).

Let me give you an example...

I was doing some recurrent training and selected a Piper Cherokee. I was doing the preflight and you can open the cowl on those aircraft. I noticed a significant oil leak behind the controllable pitch mechanism which my instructor and I decided not to fly until the mechanic looked at it. When the mechanic did, he said that it probably needs to be rebuilt but to go ahead and fly it anyway, just make sure that the oil was full prior to flight.

On my 177 we had been flying it all year, when it went into annual it was found that the piston controlling the constant speed propeller was way out of spec and that the hub had corrosion. The entire prop had to be replaced. We were flying it and it was behaving just fine, but could have failed at any time.

The point is that the issues that will stop your engine from running or make your prop run away are usually not visible anyway. Keep it topped up with oil and pay attention during run-up and you should be fine. Usually I take a flashlight and peer around in the compartment as best I can to make sure nothing has taken up residence in the engine, but aside from that, there isn't much else to do preflight.


How do A320 pilots trim? So, I am very familiar with the 737NG, and there is a trim switch on the yoke for vertical trim. However, I can't seem to locate this trim switch in the A320. Is there a trim switch on the joystick in an A320? If not, how do they trim?

The pilots do not manually trim an Airbus in pitch. The flight control computers provide automatic trim:

The normal-law flight mode is a load-factor-demand mode with automatic trim and protection throughout the flight envelope.
Following normal law, the sidestick controllers set the elevators and THS to maintain load factor proportional to stick deflection and independent of speed.
With the sidestick at neutral, wings level, the system maintains 1 g in pitch (corrected for pitch attitude), and there is no need for the pilot to trim by changing speed or configuration. Pitch trim is automatic both in manual mode and when the autopilot is engaged.

(A320 FCOM - Flight Controls - Description - Normal Law - Flight Mode)
There is however a mechanical backup:

The pilots use mechanically interconnected handwheels on each side of the center pedestal to control the trimmable horizontal stabilizer.

(A320 FCOM - Flight Controls - Description - Cockpit controls)
You can see the full flight control logic in the following image. The pitch trim is indicated by THS (Trimmable Horizontal Stabilizer):

(image source: A320 FCOM - Flight Controls)


Why does FAA not include certain SIDs and STARs in its CIFP file, even though they are regularly used in flight planning? I was correlating the instrument flight procedures found in flight plans from 1st April 2019 with the ones included in FAA's CIFP database. I noticed that in those flight plans there are some SIDs and STARs which are not coded in the CIFP file. Is that possible? If yes, is there any reason why these flight procedures are omitted?

Examples (SIDs):

JITKA2: KSGU.JITKA2.JITKA. (...)
MCOY2: KMCO.MCOY2.GUANO.. (...)

Yes it is possible and it is mentioned in the accompanying CIFP Readme pdf. Specifically, it states that

  Procedure types that are not yet included in the CIFP: ILS CAT II, ILS CAT III, ILS PRM,
  Converging ILS and Visual procedures are not included in the CIFP.

  Not-In-CIFP Spreadsheet: ILS (Category 1 only), LOC, SDF, LDA, VOR, NDB, GPS, RNAV
  (GPS), RNAV (RNP), GPS Overlays, GPS and RNAV (GPS) helicopter approaches, SIDs and
  STARs that do not appear in the CIFP will be listed in the Not-In-CIFP spreadsheet. Note that only
  FAA-developed procedures are included in the CIFP. Approach types listed above that are developed
  outside the FAA, such as Navy or Air Force procedures, will not appear in this spreadsheet.

In other words, even though you can at least acknowledge their existence by searching for the missing SIDs and STARs in the aforementioned xlsx spreadsheet, you do not have any information about their structure. As for why they are not included I can not tell for sure, but as far as I could realize from my own research, the few procedures not included in the CIFP file belong to the "old" IFPs (conventional, non-RNAV). This might mean something, but in any case it is my own (un)educated guess and by no means anything that can be confirmed from an official source.


Does a pilot need clearance to enter the traffic pattern? In one video, I saw a Cessna that got its instructions to enter the pattern along with landing clearance, but I saw another where the pilot just flew in and got clearance somewhere around late-downwind.

Edit: Still confused here, if you need a landing clearance to enter traffic, then why do diagrams like this exist: (Figure 4 indicating the recommended area landing clearance should be given)

And why do you see so many videos on youtube of late landing clearances? And why do I see people get cleared to land when they're on downwind abeam to the numbers if they already have clearance?

The US AIM (Aeronautical Information Manual) says:

  When necessary, the tower controller will issue clearances or other information for aircraft to generally follow the desired flight path (traffic patterns) when flying in Class B, Class C, and Class D surface areas and the proper taxi routes when operating on the ground. If not otherwise authorized or directed by the tower, pilots of fixed-wing aircraft approaching to land must circle the airport to the left. Pilots approaching to land in a helicopter must avoid the flow of fixed-wing traffic. However, in all instances, an appropriate clearance must be received from the tower before landing.

(AIM 4-3-2-b.)

(AIM Fig 4-3-1)

So it is mandatory to receive a landing clearance, but if traffic flow doesn’t demand it, there is no need to fly the traffic pattern. The controller basically has a lot of freedom here, but the standard is to get instruction to join it, even if this means to join a long final.


Which aircraft is this? I was curious if someone could help me gather some more info on this aircraft.  I have looked it up in the FAA.GOV site and it does not match.  Is there a way to find out info on this plane that flew around the Springfield Illinois area around 1946, possibly before?  Also, this is a Stearman?  Is there anything else interesting or remarkable about this aircraft?  Thanks!

Looks like a Boeing Stearman to me.

I couldn't find anything based on the registration (NC55383) of the aircraft.

Source: wikimedia / scan from Robert L. Lawson (ed.): The History of US Naval Air Power. The Military Press, New York (USA), 1985. ISBN 0-517-414813, p. 72. US Navy cited as source.


How is an airplane towed/recovered after an emergency off-field landing? I understand that there may be many different scenarios and situations, and that a similar question has some answers to this, but I was wondering if there are answers with existing examples. Some different scenarios are as follows:

General Aviation Airplane:

Landing on the beach
Landing on a road/interstate highway
Parachute Deployed Landing (Cirrus SR22) in a dense forest
Ditching in water

Large Jet Airplane:

Landing on the beach
Landing on an empty road/strip (such as the Gimli Glider)
Ditching in water (such as the Hudson landing)

I understand that the first priority is saving the souls on board. However, after that, the second-most important priority would be to recover the airplane as it is definitely a very valuable asset to the owner/company.

For all the above scenarios, what is a proven/tried method of recovering and towing while ensuring that the aircraft (or parts of it) can be put to use again?

This really breaks down into a few categories:

Flyable aircraft, Flyable location

For general aviation aircraft or airliners that are in flyable condition (or only require minor repairs) and are located somewhere you can fly them out of the usual solution is to offload as much weight as possible, take off, and fly to an airport.

There are countless cases of light GA aircraft taking off from roads or fields after precautionary landings.  In the large aircraft world the Gimli Glider flew out of the racetrack, and TACA 110 took off from a nearby road.

Flyable or Salvagable aircraft, Unflyable location

If the aircraft is flyable but can't take off from its current location, or if the aircraft is salvageable but requires more extensive repair work than can be accomplished where it is, alternative transport methods need to be considered.

For light aircraft the usual solution is to disassemble the aircraft, load it on trucks, and take it to an airport where it can be reassembled and repaired to be flown away.
This is also an option for most airliners, and was in fact the original recovery plan of action for TACA 110 that I mentioned above.

Disassembly, trucking, and reassembly is generally more expensive than flying the aircraft out of wherever you landed it, but aircraft insurance policies generally include provisions for this because simply leaving the aircraft where it is will often be even less economically attractive.

Wrecked aircraft, wherever it is

If an aircraft is largely intact but unlikely to fly again in the near future (or ever) due to damage the recovery operations are effectively the same as above, but they're dictated by legal and financial requirements: Environmental regulations may preclude leaving a wrecked aircraft wherever it landed, and financially the components and materials may be salvageable or valuable as scrap. As long as the costs of recovery are less than the profit to be made (or the fines to be incurred just leaving the aircraft where it is) and the hazards involved in the recovery are manageable the aircraft will usually be recovered.

On land the aircraft (or pieces of it) will once again be loaded onto trucks to be transported somewhere where they can be examined and then stripped/sold.

Aircraft in relatively shallow water will be generally recovered by dredging or hoisting with crane if doing so is feasible. This gets most of the "big stuff" (wings, fuselage sections, etc.) though in a badly damaged aircraft smaller pieces may be left where they are. (The recovery of US Airways 1549 is particularly spectacular in this regard, as it's hoisted basically intact.)

Aircraft in deep water are often not recovered - it's simply not feasible from a financial or risk management standpoint (sending people down to an extreme depth just to recover a machine that's going to be cut up and sold for scrap is hard to justify).


Which type of fan is better for wind tunnel testing? I would like to build a small wind tunnel to test a miniaturized wing/airplane. I have two options, using axial blower (picture 1) or using centrifugal blower (picture 2). The first will be the wind source for "pipe" tunnel while the second one will be connected to a ducting tunnel. The size and the power (cfm) will be provided as per requirement.

Then my question: which one is better of the two? Or, is any other better alternative?

You could make either one work, especially for a "straight  through" tunnel.  The key is to smooth out the turbulence after the fans to as straight and undisturbed a line as possible.

Smoke trails help check your wind stream before the model is put into place for testing,
and remain valuable to see changes in the wind flow pattern as it passes over the forms.

There is an excellent article on the internet:  howstuffworks wind tunnel, and a very good diagram showing post fan stages such as stators, vanes, diffusers, and settling chamber that help create a desirable flow.

For testing of lower subsonic designs, a straight through tunnel, such as the one the Wright brothers built, may be easiest to construct.


How can I find out if the FAA has ever sanctioned a pilot? Is there any easy way to check to see if a CFI or commercial pilot has had past problems with the FAA?  The question came to me after an old thread in one of the aviation forums pointed me to this crash report:  https://www.wfsb.com/news/waterbury-flight-instructor-among-killed-in-ny-plane-crash/article_06e41c00-d066-11e8-a98c-7beca823cc54.html

The report says the pilot had had several enforcement actions against him, including having his CFI certificate revoked for falsifying logbook entries.  My guess is his two passengers would have liked to know this before going on their fatal flight.  The FAA certificate database only shows his ratings, not the enforcement actions.  Where else could they have looked?

I asked FAA Airmen Services about this. There is no easy way to do what you want, as there is no online database that can be queried for pilot enforcement actions. They said you can send them a query by mail or email using this format:

                       In accordance with the Privacy Act

    Date:

    TO:
    FAA
    Aviation Data Systems Branch, AFS-620, ATTN:  Privacy Act
    PO Box 25082
    Oklahoma City, OK 73125
    Email:  9-amc-afs620-pa@faa.gov

    FROM:
    COMPANY NAME
    NAME OF COMPANY REPRESENTATIVE
    STREET/MAILING ADDRESS
    CITY STATE ZIP CODE
    Email address:  <Please enter your email address here>

    Under the authority of the PRIVACY ACT, I am requesting verification of
    current airman medical certificates, current airman certificates indicating level,
    category, class, and associated type ratings, including any limitations to those
    certificates and ratings and any and all information concerning FAA
    accidents/incidents, and/or FAA enforcement (AIE) history for the following
    airmen:

              Name:                              Date of Birth:            Certificate Number:
        1.
        2.
        3.
        4.
        5.
        6.
        7.
        8.
        9.
        10.

I understand that the response to my request should be mailed to me within 20
federal working days.  If you have any questions, please contact me at:  XXX-XXX-XXXX.

Sincerely,

I am surprised there isn't a faster mechanism for this. Enforcement actions should be public record, same as criminal conviction records. But I guess this process is geared towards background checks of pilots by potential employers, not the general public. Odds are it would take an act of Congress to change this.


How do rate gyros and other sensors send information to the flight control computer in an F-16? How do rate gyros and other sensors send information to the flight control computer in an F-16? I mean is it a hardwired communication or it is done through a bus? If by bus, what is the bus called?

I have read some articles about A-Mux. Is it the bus that the gyros transmit data through? I have the same question about the actuators. How does the flight control computer send information to the actuators? By bus or hard-wired? If you have references, that will be appreciated.

The F-16 uses a MIL-STD-1553 data bus and was the first aircraft to do so.

References:

https://www.testandmeasurementtips.com/making-measurements-mil-std-1553-connections/
https://www.aim-online.com/wp-content/uploads/2019/01/aim-ovw1553-u.pdf


Do fighter jets experience a reaction or recoil force upon firing a missile? When fighter jets fire a missile, do they observe any kind of reaction force due to firing the missile? If yes, how is this observed by the pilot? If no, why not?

No, rocket missiles are recoil-less weapons.

When firing a gun, the charge burns inside the chamber and the generated gasses do not escape before the shell leaves the barrel, so the reaction force is transferred to the body of the gun.

When firing a rocket missile however there is open space behind he missile and the reaction force only accelerates the generated gasses that are ejected off the back and does not affect the launching platform significantly. This is true for missiles launched from tube (like Bazooka, TOW or Hydra 70), off a rail like the wing-tip sidewinders or from free fall like most of the heavier air-launched rockets.

The lack of recoil is an important advantage of rockets. Bazooka can be fired from shoulder while anti-tank gun with comparable explosive charge is heavy device and needs good support to handle the recoil.

On the other hand rockets need more propellant than comparable gun shells, because the generated gasses leaving at high speed carry away a lot of kinetic energy most of which would be available for the shell in a gun.


What is the correct definition of "spanwise" and "chordwise" with a swept wing? What is the correct definition of "spanwise" and "chordwise" with a swept wing?  For example, in the context of "spanwise airflow" and "chordwise airflow"?
a) spanwise is from root to tip, generally following the quarter-chord line, and chordwise is the direction that gives the shortest distance from leading edge to trailing edge, very roughly perpendicular to the quarter-chord line.  I.e., roughly as illustrated in this related question (either diagram): Where is the spanwise flow? How does the span wise flow point the air towards the wingtip?
b) spanwise is perpendicular to the aircraft's longitudinal axis, and chordwise is parallel to the aircraft's longitudinal axis.
c) either of the above definitions could be considered to be correct, depending on the context
d) other
Not meant to be strictly multiple choice, those options are just offered as food for thought-- if one of the choices is almost right but needs some tweaking, please elaborate--
Among other things, the intent is to understand whether the diagrams linked in option a), exactly as drawn, really illustrate any net spanwise flow at all.

b) is a correct description of both .
"Spanwise" is perpendicular to the aircraft's longitudinal axis because it does not relate to the width of the wings, but to the span of the aircraft. which includes both the wings and the fuselage. Consider that the wings of most aircraft and all birds, don't really have a clear "root" where  the wing ends and the torso/fuselage begins.
"Chordwise" is parallel to the aircraft's longitudinal axis because that is the way the air flows. Any other angle would not make sense. It might be of interest on some specific airplanes, but otherwise the only thing that matters is the general airflow, which is parallel to the aircraft's longitudinal axis for cruise flight in most any aircraft.
Swept wings, be they aiming forward or aiming back, have a characteristic that can't be defined by either span or chord. The same goes for delta wings for which every chord over the span of the wing is different.


What if a commercial airline pilot misses their flight? Pilots need to arrive at the airport 1 hour before their departure. What if one of them is not able to report on time (due to any circumstances or reason) and also misses the departure time of flight.

In that situation, will the flight get delayed?
Will the airline wait for the pilot to come or will they find some other pilot for this flight?
Are there any extra pilots always available for handling this kind of situation?
What action will be taken against the pilot for missing the flight?
Can this type of issue have any effect on a pilot's career (like any kind of ban or suspension or penalty)?

Airlines try to maintain some ratio of crews to fleet to provide surplus bodies to cope with this sort of thing.  For Regionals, where the average aircraft hours are around 2500 hrs per year, and each pilot flies somewhere around 800-1000 hrs per year, you need 3 crews per a/c just to meet the baseline operational need.  Add absentee time for vacation requirements and booking off sick, training etc, and you need 4-5 crews per a/c to be able to sure that you can keep each airplane running 2500 hrs/year.

As a result, Regional operators will try to keep about 8-10 pilots on staff per aircraft and if they are below that, problems start to happen.  You can get by somewhat with crews working overtime, but there are limits to that due to regulatory duty limits.  Airlines have a reserve system to organize crews to make sure there are available idle bodies to step in if required.

There is "reserve" and "ready reserve" duty.  Reserve duty is being on-call at or near home and able to report within a reasonable time of being called, like 2 hours.  These are to cover book-offs with advance notice, like a pilot calling in sick 6 hours before.  Ready reserve duty is where the pilot has to go to the airport crew ops office in uniform and basically hang around ready to go on short notice for someone who doesn't show or who calls in at the last minute.

So:

Yes probably, if there isn't a ready reserve pilot on hand.
They'll stick in a guy/gal on ready reserve if they have one.  If not, the flight will get delayed or cancelled.
See above.
Booking off sick or calling in because you had a traffic accident or home crisis isn't a problem.  The problem is failing to call in and leaving people hanging.  You better have a very good reason for not showing up and not calling in.  That would result in some kind of disciplinary ding on your record, getting worse if you do it more than once.  It would depend on an airline's union contract, or if non-union, the management's disciplinary policy.
In a union shop, for a one time thing, probably not if not repeated.  Union shops give you the luxury of having to screw something up several times to really get hammered for things that are not safety related. It'll depend on contract language; but you could get suspended or let go eventually.  In a non-union shop, it could hurt you in terms of promotion, or if you did it more than once you might get let go more readily than at a unionized airline.

Bottom line is, the next worst thing to unsafe pilots are unreliable pilots.

In the Regional airline business especially, the shortage of crews is really starting to bite and airlines are not able to maintain the necessary staffing "fat" as the flow from the bottom thins out and the majors suck up the experienced crews.  Many cancelled flights with Regional operators are due to lack of crews, not mechanical or weather issues.  The 1500 hr "Colgan Rule" requirement in the US has made this that much more severe, but up here in Canada where Regionals can still take 250 hour flight school graduates under special programs where they are groomed in-house, there are still not enough to cope with retirements and flights are being cancelled for lack of crews.

This is all tied to the final stages of the movement of the "baby boom" demographic wave, which is now resulting in a flood of retirements of airline capts born in the mid 50s hitting retirement age, which should finally start to taper off in the next 10 years once the peak of the wave is mowing the lawn at home.  Everybody's vacuuming up pilots from the levels below them, resulting in shortages all the way down the chain.


Is it possible to fully utilise excess heat from an aircraft to power other systems required for the aircraft to function? Is it possible to fully utilize excess heat from an aircraft engines to power other systems required for the aircraft to function, using heat exchangers and other clever engineering tools and techniques? This would seem to me to amount to massive energy efficiency and fuel savings.

There are heat engines that convert heat into mechanical energy, which can drive useful things around the aircraft. Examples that actually drive systems that we use are

The steam turbine used for electrical power generation in remote area's, driven by the waste heat from gas turbines.
The stirling engine, used for driving submarines due to it being whisper quiet.
The classical steam engine, also very quiet.

All these engines come at a weight penalty of course. It makes a lot of sense to add a steam turbine to a gas turbine in a power station; adding a steam turbine next to the jet engine is less clearly beneficial. It has not been done.

So yes some of the waste heat of the aircraft engines can be used. But thermodynamics says that never all heat can be transformed - the theoretical maximum efficiency is a function of the maximum and minimum temperatures. Only a heat engine with a perfect Carnot cycle, a heatsink of 0 K or an operating temperature of $\infty$ K and no heat loss other than through the engine process will transform all heat. And we cannot make that in an environment that is neither 0K nor $\infty$ K.


What is a Ground Power Dispatch Switch? I've been going over the new Master Minimum Equipment List (MMEL) for Textron Aviation Model 500 Series Citations and on page 36 a Ground Power Dispatch Switch is mentioned but I can't find any information or pictures of it online.

Can someone explain?

The Citations have an auxiliary battery in the nose that lets you power up limited avionics, like a comm radio and one of the FMS units and displays, to allow you to get your clearance and program the FMS before engine start, in the absence of a ground power cart, without having to deplete the main battery.  It's controlled by the Ground Power Dispatch Switch.


Where exactly is the 700 and 1200 foot AGL for class E airspace measured from? Are the AGL numbers measured from the Maximum Elevation Figure listed on the sectional?

So where is it measured from
Well, quite literally the 700 foot and 1200 foot numbers are AGL as in the distance between your aircraft and the ground at any point. If there is a mountain in the transition area, the 700-foot AGL figure would have a mountain-shaped "bump" in it. It does not take the AGL figure from some highest figure in the area.

The number you refer to, the Maximum Elevation Figure, is calculated based on the highest obstacle in the quadrangle, see the FAA Website chart legend:

So as you can see, the blue number in the quadrangle does not show the MSL of the "sector" (quadrangle), but it is a simple calculation based on the height of the highest obstacle in the quadrangle + 100 feet and some rounding.
The FAA does a similar calculation for natural terrain features:

The big take-away here, in reference to your answer on another question, is that you cannot use this number to determine if you are within Class-G airspace since it takes an elevation figure from some obstacle (man-made or natural) that may not be anywhere near you. So flying at the MEF + 1200 feet does not mean you are in Class-G since, as in the second example, that mountain is a long way away from Ute Park or Red river (at Red River you would be more like 6200 feet AGL).
The AGL of the highest man-made obstacles are shown on the chart underneath the MSL elevation:

But it may be omitted in congested areas of the map and only shown as MSL.


What is the procedure for handing over controller positions to the next shift? I'd like to know how a controller of the previous shift hands over the position to the person of the next shift.

I imagine the next person should be present at the console for at least X minutes, so he or she knows what is going on. Is X defined by some regulations (or ICAO recommendations), or is it completely up to the ATC facility to decide?

Is sitting next to the console enough? Or, should there be some sort of briefing (by the current controller / supervisor)?

(Note: I don't want to tag this to a specific country. I am interested in whatever country the answer applies to.)

I've asked an ATCO friend of mine who is in Greece in area control center and he told me is that there are no regulations; only good practices. For example, since for each sector you don't have one but two controllers, you don't change planner and radar operator at the same time. You might switch them 15 or 20 minutes apart. The supervisor is not involved in the process (there are several positions changing at the same time, who should they attend first?) and besides they are already busy with bigger things.

The current controller will need to brief the next one only if there is something unusual. Otherwise, the controller knows what sector they will take over and the sector peculiarities. Glancing at the current traffic will give them a good picture of what is going on. The relieved controller can stay next to the one who relieved them as long as they want but again, there is no time specified by regulations. But usually one or two minutes is enough. Usually an informal "Joe can I go? Need me anything else?" is enough and in the vast majority of cases the response will be affirmative.

This is specific for the Hellenic ACC, I don't know what happens in approach or tower positions although I have a feeling that things are not extremely different.


What is the effect of airflow speed on separation? We know that in real viscous flow, boundary layer exists around the airfoil and there will be a separation point which flow starts to separate from the back of the airfoil( velocity gradient equal zero at separation point). If the flow speed increases, will separation occur earlier or later?

In a subsonic flow, the separation point moves downstream as Reynolds number increases, and Reynolds number increases with free stream velocity.

Demonstration on a cylinder-shaped airfoil:

Source

From Wikipedia:

  Reynolds number is the ratio of inertial forces to viscous forces
  within a fluid which is subjected to relative internal movement due to
  different fluid velocities

Separation occurs at the location the laminar airflow stops being accelerated, and is decelerated by areas of upstream turbulent airflow in separation bubbles created by friction (viscosity):

Source

Velocity gradients in the boundary layer at different points in the transition area where the flow transitions from laminar to turbulent:

Source, adapted

Velocity is decreasing near the surface due to friction, and at some point becomes negative. Separation bubbles appear between the laminar flow and the airfoil. In a bubble there is a secondary reverse flow and a region where air is stagnant. Downstream the bubble, air is turbulent:

Source, adapted

While other elements affect the boundary layer separation point, this one is the largest. To counter this effect, the momentum of the laminar stream must be increased relatively to frictional forces. This is done (by definition) by increasing the Reynolds number, e.g. by increasing the airspeed.

Increasing airspeed can be obtained by accelerating the aircraft, but also by other ways. For example, different devices are used to delay the separation of the boundary layer when the aircraft must be slowed down. It consists on accelerating ("re-energizing") "dead air" near the surface, e.g. using high speed jets or vortex generators.

This is for instance the principle behind slats and slotted flaps:

Source, adapted

The boundary layer separation is due to flow deceleration as it moves away from the leading edge and an adverse pressure gradient appears (potential flow theory).

The lower energy flow is more prone to perturbations, vortexes appear and disappear, increasing in importance. Portions of vortexes have a velocity opposed to the free stream velocity, this creates areas of "dead air". Viscosity takes over inertia. This ratio between inertia and viscosity effects is the very definition of the Reynolds number.

By increasing velocity (actually the Reynolds number), this effect is minimized: The separation point moves downstream, as the effects of the adverse pressure gradient are countered on a longer distance as visible on the velocity gradients shown on the flap/slat picture above.

Flaps/slats have the additional advantage (over vortex generators for instance) of increasing the wing surface, hence restoring lift lost when the airplane was slowed down.


How long would the engine of a Tecnam P92 Eaglet run for with the fuel selectors turned off? I'm wondering about a scenario where a P92 has been flying for at least 30 minutes or so, at say 4,000 RPM and 2,000' AGL at standard temperature (I'm not sure if these details matter). With both selectors on, you would then shut off both fuel selector valves. With no fuel coming through the lines, how long would it take for the engine to starve and stop working?
Flight manual for reference: http://www.whangareiflyingclub.com/wp-content/uploads/2012/10/P92-Eaglet-LSA-flight-manual.pdf

It comes down to the fuel volume in the gascolator, lines, pumps, and float chambers of the Bing carburetors the Rotax 912 uses.  Without knowing the precise numbers, we can make an educated guess.
So say it's burning 17 l/hr at cruise, which is 283 CC/min.  I don't know the exact number, but say the Bing carb's float chamber holds 50 CC for a total of 100, and the gascolator/filter on the firewall holds another 100 cc of gas, maybe another 50 CCs on the lines between the gascolator and carbs, and another 50 CCs in the lines running to the shutoff valves. Add another 50 CCs for the pumps etc.
So say somewhere around 350 CCs of fuel is available once you shut off the supply, although the pumps won't be able to draw all of it due to the lack of venting at the opposite end at the valves, and it'll depend on the effectiveness of the fuel pump in creating a vacuum between the fuel and valve as it's drawn.  Maybe it'll be able to draw 300, which will run the engine for about a minute, maybe a minute and a half at the most.  Maybe quite a bit less.
So I would go with somewhere between 30 and 90 seconds.


What is the front glass in fighter planes called? What is the front glass in fighter planes called? I mean the one which had the reticle marked in them not the canopy glass. Cockpit part on google doesn't seem to tell what I want to know.

Are there any other uses of it besides targeting, because I have seen them only in fighter planes/jets?

When were they first employed?

It's a Heads Up Display, or HUD.

The HUD can display a number of different pieces of information, including performance data such as airspeed, altitude, and attitude, navigation data such as waypoints or ILS glideslope, or weapons data such as the selected weapon or the targeting reticle you mentioned. Thus, its uses are varied - depending on how sophisticated the system, basic aircraft control may be accomplished using only the HUD. In some modern fighters, there may be additional data on a Helmet Display (or in the case of the F-35, the helmet may have the only display).

It is not just used on fighters - some airliners, cargo planes, and trainers have HUDs:

(C-17)

(T-38)

(Airbus A380)

As for your last question, per fooot's comment, this question and answer has more information.

  The Blackburn Buccaneer was the first production aircraft with a HUD and entered service in 1963.


With the upgrade of the 737 to the Max model, what major changes are incorporated? The Boeing 737 was originally designed in the 1960's and flew into the 1980's before a major redesign (the 737-700, -800, and -900 models) was implemented.

Coming up in a few years will be the next major revamp of the line as the 737-Max series (737-7, 737-8, and 737-9).

What major changes have been incorporated in these revisions?

There are of course a lot of tiny changes that Boeing would have done to the aircraft that most of us wouldn't notice, but for brevity I've just included the major changes between the 737NG series and the upcoming 737MAX.

The CFM LEAP-1B engine replaces the current CFM56 engines. Some of the significant improvements in fuel efficiency (15% savings minus drag from larger engine touted by CFM) come from a much higher bypass ratio (from 5.3:1 to approximately 9:1) and materials that can tolerate higher temperatures. Chevrons (saw-toothed tips at the end of the nacelle) have also been included to reduce engine noise on takeoff.
The engine change required changes to the nose landing gear to allow enough clearance from the ground, extending the nose gear by about 8 inches (20cm) and modifying the nose gear bay to allow it to fit into the existing space.
The AT (Advanced Technology) winglets replace the 737NG's blended winglets. The AT winglet incorporates two portions, done to reduce the weight required (compared to a larger blended wingtip) while still reducing block fuel burn by about 1.5%.
Fly-by-wire spoiler system reduces the need for long cabling between the cockpit and the spoiler hydraulic actuators, saving weight, reducing stopping distance by quicker actuation and increasing the accuracy of the controls.
Redesigned tailcone and modifications to elevator to improve aerodynamics, removing the requirement for vortex generators (VGs), which improves predictability and control by making the air turbulent, but as a result increasing drag.


How does vertical separation work above FL400? The information mentioned in "Jeppesen Airway Manual" is that after FL400, fight levels are FL430, FL470, FL510 for the 'even' FL's column.

Normally, I would expect every level divided by a thousand feet to be usable (FL410, 420, 430, 440 and so on). Why is this not the case above FL410?

For flights above FL410, 2000 feet of separation is used. Which makes all flight levels odd numbered, →410, ←430, →450, ←470, →490, ←510, ...
So for each direction as indicated above by arrows, it'll be 4000 feet.
The 2000 feet separation is because the higher up you go the less accurate an altimeter becomes, so it's for safe separation.
Even/odd is just an indication of direction in this case, which can be north/south or east/west, as explained here: Does ATC direct flights to fly eastbound at odd levels and westbound at even ones?

(Image source) Before RVSM came along, flights above FL290 were also separated by 2000 feet, compared to 1000 feet below FL290.

Between 1997 and 2005 RVSM was implemented in all of Europe, North Africa, Southeast Asia and North America, South America, and over the North Atlantic, South Atlantic, and Pacific Oceans.
[Between 2007 and 2011 China and Russia implemented RVSM.]

RVSM in essence is a reduction from 2000 to 1000 between FL290 and FL410 as long as the aircraft shows that its altimeters maintain their accuracy—among other things such as an operative autopilot.

Related:

Does ATC direct flights to fly eastbound at odd levels and westbound at even ones?
What is the maximum altitude of barometric altimeters?
Is it legal to fly in RVSM airspace with an inoperative autopilot?


Can airplanes transmit/relay flight data to ATC's periodically while in flight? The flight data recorder is one important piece of information in the event of a crash. Can this information not be transmitted or relayed to the ATC's while the flight is air borne so that they don't have to wait to recover the data recorder after a crash ? I mean to say that periodically the data can be sent back to a ground controller when the signal strength is high and it can be logged. Please let me know if there are any limitations to the amount of data that an air borne flight can relay back to the controller.

No, there's no data relayed like this to ATC. All ATC really gets is the filed flight plan, and then the transponder data. ATC just cares about organizing all the traffic in the skies, and making sure it is safe, orderly, and expeditious.

Some airlines use a system similar to this to relay maintenance data to the airline from the aircraft, that's how AF447 was found to have something wrong, and how they generally found it's location quickly(I think within 48 hours debris was found from the a/c due to the location info through ACARS(Aircraft Communication and Reporting System)). This system, and it's capabilities are optional and variable depending on what the airline wants to spend. This is why there's so much controversy over the loss of MH370, since they didn't have the full reporting schedule, and a very basic version.


Why would a RAT be deployed at takeoff? (Source)

Is that a Ram Air Turbine (RAT) on the port side below the wing? Why is it already deployed and spinning during takeoff?

This answer mentions a minimum airspeed at which RAT can be deployed.

The plane in your question is the Saab 37.

According to x-plane.org about this plane—

  Emergency power is supplied by a ram air turbine just before the left wing leading edge, which extends automatically on hydraulic power failure, and just before touch down. (Earlier, it was also always deployed whenever the landing gear was down.)

They cite Air Power Journal, Summer 1993, various issues of FlygvapenNytt and other Swedish air force informational material.

The Swedish Wikipedia also says the same thing—

  On some military aircraft, such as the Saab 37 Viggen, the RAT is used during takeoff and landing for the pilot to be able to maneuver the plane in case of an engine failure at low altitude.


Does the flow in an afterburner have to be subsonic? This question is prompted by the problem on page 350 of the fluid mechanics book by Landau and Lifshitz. The problem states, "A small amount of heat is supplied over a short segment of a tube in a perfect gas in steady flow in the tube. Determine the change in the gas velocity when it passes through the segment." This seems to me to be applicable to an afterburner. The solution is obtained by using conservation of mass flux and momentum flux and then increasing the energy flux by the heat added.  The change in velocity turns out to be given by,
\begin{equation}
dv=\frac{(\gamma-1)q}{\rho(c^{2}-v^{2})}
\end{equation}
where $\gamma$ is the ratio of specific heats, $q$ is heat added per unit cross-section per unit time, $\rho$ is density, $v$ is velocity and $c$ is the local speed of sound. This formula says that if the flow is supersonic $v>c$ then $dv<0$ and the gas velocity slows down. The addition of heat only increases the gas velocity if the flow is subsonic. So, my question is, "Does this result imply that the flow in an afterburner is subsonic?"

Afterburners are subsonic but not because of that equation.
Afterburners are typically subsonic for a couple of reasons. First combustion is easier at low speeds. While supersonic combustion is possible (see scramjets), most times the combustion areas of a jet are the points where some of the slowest flow through the engine occurs. Secondly, the goal of the afterburner is not to increase velocity or pressure (in fact ideal combustion is isobaric, and real combustion features a pressure loss) but to increase temperature. The reason behind this is that high temperature gas releases more energy for the same decrease in pressure than low pressure gas. This is how turbine engines are able to operate, and why combustion occurs at the highest possible pressure. After the afterburner the flow becomes supersonic traveling through the nozzle, which in an engine equipped with an afterburner is almost always variable geometry.


How many passengers can an Airbus A380 carry? What is the passenger capacity of an A380, and how many suitcases could it carry?

Wikipedia lists three basic configurations for the A380-800:

407-526 (3-class)
644 (2-class)
853 (1-class)

However, different airlines have different configurations. The lowest number of seats is Korean Air, with 407. The highest number of seats is Air France, with 538. Emirates has discussed plans for a configuration with 644 seats but it does not appear on the list (or on SeatGuru).

As far as baggage, this thread states that the A380-800 might carry 19 LD-3 containers of baggage, or 3002 cubic feet, which is for about 471 passengers. The bulk hold, which is for loose baggage, can hold 1,525 kg or 14.2 cubic metres (501.5 cubic feet), and the A380-800 can carry 8,000 kg of cargo in addition to a full passenger load according to Emirates.

An average suitcase is about 0.1 cubic meters in volume. If the bulk hold is 14.2 cubic meters, then it could theoretically fit 142 suitcases. But an average suitcase weighs 50 lb, so 142 suitcases would weigh 3220 kg, which is over twice the weight capacity.

The LD-3 containers add an additional 85 cubic meters of space, or 850 bags. This is a total of 942 bags, which for around 500 passengers sounds very reasonable.

But wait, there's more! What if the rest of the cargo capacity was filled with luggage?

Emirates above claims a total of 12 PMC and 44 AKE of cargo capacity. The properties are as follows:

PMC

23 cubic meters (max)
6700 kg capacity

AKE

4.3 cubic meters
1497 kg capacity

This is a total of 465.2 cubic meters of capacity, or 4652 suitcases, or 105,505 kg. The containers could hold a maximum of 146,268 kg.

So the bulk plus container capacity is 4794 bags by volume. This is assuming every container could be packed completely full of bags with a density of 227 kg/cu m, so the actual numbers would probably be lower.


What does the orange colored text in a SkyVector route indicate? If you use a pre-made route in skyvector.com, sometimes there will be orange text.

For example: from KIAD to KTPA with default cruise settings, the second route in the list will have DADES6 in orange.

What does this mean and how would you program these into the FMC?

The Dades 6 is an arrival procedure also known as a STAR (Standard Terminal Arrival Route).

The plate that lists the route and altitudes/speeds for the arrival can be found here.

If you are using a flight simulator, there should be an ARR/DEP page on the FMS that includes (among other things) a list of all the arrivals for the airport you have set as your destination. You can then select the arrival and the appropriate runways.


When should the term "pan-pan" be used instead of "Mayday"? FAAO JO 7110.65, §10-1-1 states that "pan-pan" can be used to indicate a state of urgency:

a. An emergency can be either a Distress or an Urgency condition as defined in the "Pilot/Controller Glossary."
b. A pilot who encounters a Distress condition should declare an emergency by beginning the initial communication with the word "Mayday," preferably repeated three times. For an Urgency condition, the word "Pan-Pan" should be used in the same manner.

Under what conditions might a pilot use the phrase "pan-pan", versus "Mayday"?

Oddly enough, the FARs and the AIM do not define these terms even though they use them frequently, but it is in the Pilot Controller Glossary (see below).  This is one of those areas that I've never really been given specific training on and I guess figured that I would "know it when I saw it".  The definitions kind of support that since they leave it to the discretion of the pilot:

  EMERGENCY- A distress or an urgency condition.

  DISTRESS (MAYDAY)- A condition of being threatened by serious and/or imminent
  danger and of requiring immediate assistance.

  URGENCY (PAN-PAN)- A condition of being concerned about safety and of requiring
  timely but not immediate assistance; a potential distress condition.

Flight Safety released a report titled Use of Standard Phraseology by Flight Crews and Air Traffic Controllers Clarifies Aircraft Emergencies which includes a quote from an official in which she says that there is a misconception among some pilots about the difference between declaring mayday and pan-pan:

  I have observed many cases where a mayday is given when pan-pan should
  be sufficient.  Many pilots do not realize that this distinction is
  ATC's way of prioritizing two or more aircraft with an emergency at
  the same time.

She also included some of the most important factors to consider when deciding to declare an emergency:

  Is the aircraft in immediate danger?
  Does the aircraft require immediate assistance?
  Will the aircraft require priority handling during the approach or during any other phase of flight?
  Will the aircraft need special assistance on the ground?
  Does the crew need any assistance from other parties?

The most important thing though is not whether you declare exactly the right kind of emergency, but that you actually let them know when you need help.  Don't forget that you can also change your mind.  If you declared an Urgency condition and decide that you need more assistance/priority, you can always "upgrade" it to a Distress, and vice-versa.


Why would a C-17 Globemaster be painted in Qatar Airways livery? Just seen a C17 Globemaster painted in civilian Qatar Airlines livery.

Any idea for the reason? Is this aircraft for civilian or a military use?

It is a military C-17 of the Qatar Air Force, one of the four in operation.

It is in this livery as it is being operated by the Qatar Amiri Flight, a VIP airline owned and operated by the government of Qatar. The vast majority of the Qatar Amiri Flight fleet is painted in the standard livery of Qatar Airways, like this A340 below.

The aircraft is only operated by the Qatar Amiri Flight, not owned by it. The picture below shows the Qatar Air Force roundel on the underside of the wing.

Source: www.youtube.com


Why did FAA regulations initially prevent passengers from making phone calls during a flight? For many years, the FAA prevented people from making phone calls during a flight. Was this because a phone call interfered with aircraft communications?

While there is a chance it can interfere with aircraft equipment there are lots of other reasons as well.

It's disturbing, you would not want a can full of people yapping on their phones for 5 hours while others tried to sleep. Lets be honest does asking someone to "Keep It Down" ever really work.
It's very taxing on the cell network itself. Without going into lots of detail about how cell phones work, the short and sweet of it is that when you are moving (say in a car) your phone is constantly hopping form tower to tower. At the speeds a plane moves at you would hop tower at a rate that would be far more taxing on the system than when you are in a car and could lead to dropped calls and other connection issues.
You need to listen up! While the laws on in flight entertainment have become more relaxed over time, one of the reasons you are not to use things during takeoff and landing is these are critical times in the flight (for something to go wrong) and if it does, you need to be attentive and able to listen to instructions. This, on some level, holds true for the whole flight as well I would think.
The phone itself occupies its own frequency band outside of the band that aircraft radios use however there is always a possibility when you have 2 EM waves that interference will occur.


When does the use of afterburners save fuel? An afterburner uses a lot more fuel for a little more thrust (rule of thumb: 50% more thrust for 5 times the fuel flow with full dry power). Is a flight maneuver possible where using the afterburner will result in less fuel use than flying the same maneuver with dry thrust?

To be precise: I am looking for a situation where the aircraft transits from state A to a desired state B. The transition is possible with both dry and wet thrust. Please describe a pair of A and B where less fuel is used in the transition when the afterburner is lit!

If such a pair of states does exist it ought to be straddling a Mach boundary (I think)

e.g. A subsonic & B trans-sonic. Or A trans-sonic & B supersonic etc.

Reasoning: To get from any point A to B in parameter space should usually be a state function i.e. path independent.

i.e. You can give many tiny increments or one large increment.

In our context a parameter space means mostly a {velocity(v), altitude(h)} pair.
To go from A{v1,h1} to B{v2,h2} you need a certain thrust profile. The required thrust profile is not unique.

Now the above path independance statement is true in general, except when a dissipative force exists. Now you no longer have a state function.

Since drag, a dissipative force, is indeed a strong function of speed it will help to not linger in the high drag region i.e. transsonic region with wave drag. In this zone the drag coefficient increases rapidly and you will have a total drag much higher than at both sub-sonic and super-sonic speeds.

And that would give a high thrust afterburner the advantage needed over a dry engine: On afterburner you can zoom through the transsonic region  rapidly than trudge through it incrementally on dry thrust. Thereby saving on drag losses. You are still consuming more fuel per unit time but the time spent is reduced so much that it makes the higher specific consumption worthwhile.

Caveat: This is just an qualitative argument. A more mathematical argument is needed to add rigor to the analysis.

Edit: Maybe these schematic plots help clarify my argument.


Is it allowed to wear polarized sunglasses in cockpit? Is it true that Pilots are not allowed to wear polarized sunglasses?
What is the worst thing that can happen if wearing polarized
sunglasses in cockpit?

This FAA document describes considerations for choosing sunglasses for pilots.

Since the document concludes, that

  Polarized sunglasses are not recommended

I presume there is no rule that would explicitly forbid it. However there is always the “operate aircraft careless and reckless manner” paragraph and if you badly screwed up while wearing such sunglasses and there was grounded belief that some of the disadvantages of such sunglasses contributed to the incident, you could be charged with that.

The document quotes following reasons why they are not recommended:

may reduce or eliminate visibility of instruments with polarization-based anti-glare filters,
may reduce or eliminate visibility of LCD instruments (LCDs emit polarized light by design),
may interfere with visibility through an aircraft windscreen by enhancing striations in laminated materials,
may mask the sparkle of light that reflects off shiny surfaces such as another aircraft’s wing or windscreen, which can reduce the time a pilot has to react in a “see-and-avoid” traffic situation.

Even if your plane does not have any instruments with polarization filters and no issues with striations in laminated windshield, filtering reflections from other aircraft is definitely not what you want.

Note that in most other situations, filtering reflections (from water, cars, metal roofs etc.) is desirable and is why polarized glasses exist, because reflections from close objects can be blinding. But in aircraft you are far from the sources of reflection, so the risk of blinding reflection is low, while the reflections can alert you to presence of other aircraft that might otherwise be hard to spot when looking towards the sun.


to whom are PAN PAN PAN calls addressed? Can a PAN PAN situation be adressed directly to an ATC or must it be at adressed only at large?

This is a situation wereby the ATC was the destination before the situation of the pilote got worse.

A PAN call is like a MAYDAY call in that you are broadcasting to whomever may hear it.  However, if you broadcast a PAN call on an active ATC frequency, ATC will naturally respond to it and it's sufficient to just state PANPAN-PANPAN-PANPAN and your registration and any other information and ATC will answer, and everybody else will know to stay off the frequency momentarily.

You can broadcast a PAN call on any other frequency like a unicom, or 121.5, and whomever is listening in will likely respond.  I was once downed in the bush in a seaplane by engine trouble, becoming stuck on a remote lake, and couldn't raise anybody on the normal unicom channel even if I heard other seaplanes passing in the distance.  I saw a contrail above, and knowing airliners monitor 121.5 over sparsely settled areas, I broadcast a PAN call with my registration on 121.5. To my surprise the airliner heard me and answered.  I was able to get him to contact base on the Unicom frequency and let them know what lake I was on before he was out of range of my radio's transmitter, and was rescued with my two fisherman passengers later that day.  The only other choice was to set off the ELT and hope an airliner or SAR aircraft heard it (this was pre-SARSAT), which would have meant spending the night there at least.


Which authority is responsible for RT licensing in the Netherlands? Which authority does issue the separate RT license for pilots in the Netherlands?

I had a conversation with Netherlands CAA and they could not help me.

The Dutch authority responsible for radio communication licenses is 'het agentschap telecom', part of the ministry of economic affairs.

More information about licensing for the aviation radio bands can be found on their website (in Dutch).