What causes the inside glass of flight instruments to get hazy? Sometimes on analog flight instruments (aka steam gauges) there is a haze or fogginess on the INSIDE of the glass that is NOT condensation. You can often find it on older aircraft with older instruments. But the instruments don't all develop the haze. I've spent some time trying to determine what this is and I found a few explanations, but only one of them addresses haze/fogginess inside the glass. This is one explanation I have found:

On instruments connected to pitot static system, it is the result of small air leaks which allows air to flow into the instrument and behind the glass, overtime it causes glass to get hazy on inside due to particulates in the vacuum air.

I find this to be credible but would like confirmation.

Additionally, I've noticed similar haziness/fogginess on non-pitot static instruments like Manifold Pressure, Tachometer, and others. So, there is likely another explanation for this.

This can depend on what the actual instrument is and what (if anything) the glass is coated in.

In some cases the instrument may not have a glass panel at all, it may be acrylic or any other type of similar material. You are mot likely seeing sun damage in this case.
It may be mold or fungus. Camera lenses suffer from a similar issue. If the aircraft resides in a humid environment, maybe even trapped in a damp hanger you can get build up. Since instruments get rebuilt sometimes (some more often than others) they are opened up and resealed quite a bit in their life times. This may not always happen in a perfect environment and even a small amount of fungus can quickly damage something.
It could be interior lubricants (oil) that are thrown around the instrument as it spins at high speed.
Some of the older units are not sealed, and for that matter some may even be vented to the atmosphere as is suggested here.
It could be dust drawn in through the vacuum system that the filter failed to draw out.

  Vacuum systems are very common for driving gyro instruments. In a
  vacuum system, a stream of air directed against the rotor vanes turns
  the rotor at high speed. The action is similar to a water wheel. Air
  at atmospheric pressure is first drawn through a filter(s).


What is the aspect ratio of T-tail for common twin turboprops? I'm trying to figure out typical AR values for a T-tail configuration (at the conseptual design phase). Working with Raymer I found this table:

I can see the typical AR values for the vertical tail but I cant find anything about the horizontal one. The only info that I got is that it should be lower than wing's AR. The aircraft that I'm interested about is a twin turboprop.

Hmmmm.

[Source]

ATR42=6:1

[Source]

Dash8Q400=4:1


Can normal PC headsets replace 'aviation' headsets? Aviation headsets have noise reduction and a larger jack (1/4") than most PC headset counterparts (1/8"). But there are many excellent quality PC headsets with sound-proofing materials which eliminate external noise. So can I just plug in my PC headset using an adapter? (Let's assume that I have a PC headset of equally good build quality, and comfort)
EDIT: What exactly are the functions of an aviation headset?
I've already looked at this topic, and this doesn't answer my question - I understand what aviation headsets do, but I'm asking (out of academic interest) whether they can be replaced with a superb quality headset for a PC, like for example, the Kingston HyperX Cloud II. If not, what exactly is different other than quality and noise cancellation? Again, this is for academic interest...

Can you physically make it work? Yes. But you have to have an adaptor that fixes several compatibility issues.

Headphone impedance

Impedance is usually referred to in high and low range. Military headphones are low impedance, 19$\Omega$. Civil aviation uses 300$\Omega$, high impedance headphones. Impedance matching is not vital, but can cause some problems with sound quality. Using a low-Z headset with a high-Z output can cause distortion. A low-Z headset will also be more sensitive, so you would have to turn the volume down. You could run the risk of damaging the headset or your hearing if you have the volume up too far. The headphones you listed in the question are 60$\Omega$, which is somewhat of an in-between. There's no real standard, but low-Z are usually less than 32$\Omega$ And high-Z is usually above 100$\Omega$.

In the recording studio we considered high-Z headsets to be "universal" meaning that you could plug them in anywhere and they would work, but might be limited in volume. I used a set of low-z phones, since I could plug them into a line output and actually hear it. I was always careful to make sure volumes were turned down before I plugged them into the com boxes. They were pretty sensitive.

Microphone impedance

This will make a bigger difference than the headphones. Military systems use 5$\Omega$, low impedance mics. Civilian systems use high-Z, 80-300$\Omega$ amplified electret Mics. The headset you listed in the question lists 2.2k$\Omega$ which would be work, depending on how much amplification it has. Aircraft coms use a vox circuit to cut out noise that opens when you speak. Depending on whether there is a way to adjust the mic input the level may be too much or too little for the vox system. Too little and it won't open when you speak, too low and it will stay open and you will hear all the aircraft noise.

Phantom power

Electret mics require a power source to operate. They can either contain a battery or run off phantom power, which is a voltage supplied by the device it's plugged into. Some aircraft intercoms provide phantom power. I'm unable to find any standard voltage, but it appears the David Clark aviation headsets run on 8-16v. The standard voltage from a PC audio card is 5v. The headset you listed in the question shows that it requires 2v. I presume that, since it's made for PC use it's intended for 5v, but will operate as low as 2v. There's no way to know if 8-16v would overload it, so you would have to either adapt the phantom power or run it on a battery.

Connectors

Aviation mics have different physical plugs.

Most commonly the headset itself uses a 1/4" phono plug, wired the same way as older audio headsets with 1/4" plugs.

The microphones in aviation headsets are seperate and use a somewhat aviation-specific .206" TRS plug.

Helicopters and military aircraft use a completely different .281" TRRS plug for both headset and mic.

Airbus uses a 5-pin XLR connector for both mic and headset.

Judging from the fact that people have schematics posted on the web on how to adapt aviation headphones for non-aviation use, but not the other way around I would speculate that even the best non-av sets don't meet the challenges of aviation. Some of the physical design characteristics, such as the pressure exerted on the head pads, etc. are probably quite different from the non-av sets.

If you look at prices, aviation headsets run well more than twice the price of equivalent quality non-av sets. I'm sure some of that extra price is in design characteristics of the av sets. But, I also suspect that manufacturers will take the exact same sets, change a couple of resistors, put different connectors on them, add the word "aviation" to the box then add $500 to the price.

Images source

Aviation data found at Acousticon website


How to safely handle AVGAS (100LL)? Obviously 100LL is risky. It's got lead in it, so there's going to be some danger. But is it possible to not get lead into my system when I start flying?
It is, for obvious reasons, something I wish to avoid. I want to learn to fly, but after reading the SDS for 100LL, I'm pretty worried. Here are the hazard and precaution statements for 100LL:

H225 Highly flammable liquid and vapour.

H304 May be fatal if swallowed and enters airways.

H315 Causes skin irritation.

H336 May cause drowsiness or dizziness.

H361d Suspected of damaging the unborn child.

H373 May cause damage to organs through prolonged or repeated exposure through
inhalation.

H411 Toxic to aquatic life with long-lasting effects.

P202 Do not handle until all safety precautions have been read and understood.

P210 Keep away from heat, hot surfaces, sparks, open flames and other ignition sources.
No smoking.

P260 Do not breathe mist/vapours.

P273 Avoid release to the environment.

P280 Wear protective gloves/protective clothing/eye protection.

P301+P310 IF SWALLOWED: Immediately call a POISON CENTER or doctor/physician.

P331 Do NOT induce vomiting.

P303+P361+P353 IF ON SKIN (or hair): Take off immediately all contaminated clothing. Rinse skin
with water/shower.

P308+P313 IF exposed or concerned: Get medical advice/attention.

Some of that is common sense, but that's a lot of very concerning information. How can I avoid contact? It seems like there's not really a good way around it, but I'm really concerned and I want to balance minimizing risk with still being able to fly.
Can anyone offer some advice?

If you don't crawl underneath and breathe in the exhaust fumes from the engine, you'll be fine.  If you do crawl underneath and breathe in the exhaust fumes, you'll be dead from carbon monoxide poisoning long before any harmful effects from the tetraethyl lead combustion byproducts in the fuel.
While you don't want to ingest lots of lead, that won't really happen being around airplanes with engines running.  The old saying in toxicology is, "The poison is the dose", and whatever dose you get from casual exposure is too microscopic to matter.
My advice, as an old-timer who likes a clean world as much as the next guy, is don't become so hyper-sensitized (by mostly media coverage) to environmental exposure to chemicals that you can't enjoy life. It's not worth it.


Disadvantages of using thrust vectoring only in an aircraft with variable rotation nacelles such as the X-19 Take a quad tilt rotor aircraft such as the curtiss-wright X-19 or even a bi-tilt aircraft such as the V-22.

What would be the advantages or disadvantages of using thrust vectoring only for control of roll, pitch and yaw assuming for a moment that there is no added mechanical complexity in individually tilting each nacelle a variable rotation and assuming each nacelle can tilt 180 degrees from full vertical producing downward thrust (lift) to reverse vertical, essentially sending the aircraft downwards.

In theory, the front two nacelles would control pitch by rotating up or down simultaneously while the back two nacelles would control roll by each nacelle tilting oppositely. Combined all nacelles would be capably of controlling yaw or by changing the thrust being generated on each side of the aircraft, a yaw moment could be generated.

of course there are clear issues in the form of Cost, mechanical complexity, control of the aircraft in an engine out scenario, gyroscopic moments and control generally but purely from a flight mechanics perspective, what are the advantages or disadvantages of removing ailerons and using thrust vectoring to control the flight of such an aircraft.

Currently, it is my belief is it would allow the use of highly complex airfoil geometries that would increase the efficiency of the aircraft in flight as airfoils would no longer be necessary and perhaps increase maneuverability of what i would imagine to be large aircraft but there is no drawbacks other than those previously mentioned however, would thrust vectoring produce less turning moments than ailerons?

I look forward to any and all replies, thank you.

It is my belief is it would allow the use of highly complex airfoil geometries that would increase the efficiency of the aircraft.

The best airfoil is one that adaptively changes shape to meet current requirements (read: flaps or flaperons that run the entire length of the wing).

  What would be the advantages of using thrust vectoring only for control of roll, pitch and yaw?

That's how the V-22 works. During horizontal short field takeoffs, the engines are angled forward and upward and the flaps are fully deflected to generate maximum lift. Pitch and roll control are provided by thrust vectoring and differential thrust (the V-22 has conventional swashplates). Below is an image of a V-22 during takeoff. (source)


How is the lighting panel of an Airbus A340 designed and how does it work? I'm trying to simulate the light switch panel of an Airbus A340 with real electronics components for a model in scale (I'm doing the electronics lights with leds).

Taking a look at this PDF (page 129), I would imagine that there are several switches for these lights. But when I searched on Google Images, I couldn't find a photo of this panel, only some diagrams of A320. I never saw one that I could identify.

Question:
How is the light switch panel and/or where can I find a picture or diagram?

UPDATE 1:

Is it something like this?

UPDATE 2:

I'm seeing that some switches have 2 or more points? For example NAV & LOGO, what means 1 and 2? Off, NAV or both?

And what about STROBE-BEACON, what does "AUTO" mean?

By the way, I couldn't find the "CARGO" light, and I think that "DOME" are the Landing Gear Bay, but what does BRT/DIM mean?

UPDATE 3:
I was reading this:
AIRBUS A340 - Flight Deck and System Briefing for Pilots
But I couldn't find an image about the navigation panel.

Nav and logo.

The logo light is a spotlight which illuminates the tail to show the airlines logo at night.  The Airbus A340 has two circuits for NAV/LOGO. Logo is an auto option when the landing gear is not compressed or the flaps are extended at 15º or more." in both positions, 1 and 2.

Dome is the cockpit ambient lighting.

Strobe on means the strobe is lit.  Auto means that the strobe is on when the landing gear is not compressed - i.e. it comes on just at the point of take-off and switches off on landing.  The point of having "on" as well is that some procedures require the strobe to be turned on just before entering the active runway and when leaving it.

Hope this helps.

Picture of the panel:


What precautions should be taken when flying near the magnetic poles? Aerial navigation is designed to primarily use magnetic headings. Consider an international flight which flies a great circle route across the North Pole, or an aerial tour around the Atlantic area. What should the pilots do to avoid getting lost?

This question asks about VOR alignment, and this question discusses the coordinate system used; but neither discuss what the pilots should do in the cockpit. How do you align the HSI? And what happens if GPS has malfunctioned?

You raise an interesting question, and I assume you refer to flying near the poles using a lightly equipped general aviation aircraft. Airliners or jets usually have inertial navigation equipment that is working autonomously and will not be affected by pole proximity.

Several procedures could be taken in a general aviation aircraft to improve situational awareness:

You need indeed to deslave the HSI from the magnetic slaving transmitter in order to use it as a directional gyro manually slaved (see How does a horizontal situation indicator (HSI) work?). The directional gyro will have to be realigned manually regularly to compensate for precession (astronomical precession is 15°/hour at the pole, to the right at North pole, to the left at South pole).
Don't forget it is still possible to use astronomical navigation if you are in VFR conditions and able to see stars (at night) or the Sun (during day). This will not be very accurate but a precision better than 5 to 10 degrees could be reached without needing a sextant. Computing your location only from star positions is a complex operation, but it is rather easy to find out aircraft true heading thanks to the Sun or major stars relative position from aircraft nose. You could use this heading to manually realign your unslaved HSI/directional gyro.
Regarding GPS, it is strongly advised to check in advance GPS coverage near the pole using RAIM prediction function, either from the onboard GPS or using web servers. This will allow you to check the coverage should be assured according GPS satellite locations relative to your position (an outage is always possible). When flying in such remote locations I always bring with me a portable standalone GPS unit, in addition to panel mounted GPS.
Standard navigation (keeping track of position thanks to heading and clock) of course should be used and near coasts you could cross-check your computed position using landmarks, but above ice caps you will have few or no landmarks.
If you are lucky enough to have an inertial navigation platform on board, your position will be kept rather accurately independently of any other input, with an error of the order of 10 NM after 7 hours of flight.

The main issue you will encounter in a general aviation aircraft flying near the pole is their endurance is often limited, regulatory fuel reserves are higher than usual, airports are few and far apart, alternates may close quickly due to quickly changing weather conditions. This means that when you fly or are ferrying an aircraft in those regions, you could definitely not afford to get lost or not to be sure of your position.


How can I convert an FAA pilot's certificate to a Canadian one? What do I have to do to obtain a Canadian pilot's license if I already have an FAA one?

Transport Canada has all the information here for each FAA license type (and type ratings); the necessary forms and contacts are here. These are the basic requirements for a private pilot, for example:

  6.1 Conditions for Conversion - Private Pilot – Aeroplane.

  (1) Must hold an FAA Private airman certificate with airplane category and
  class rating(s).

  (1) Age: Must be at least 17 years of age.
  (2)
  Medical fitness: Must hold either a Category 1 or Category 3 TCCA
  medical.
  (3) Knowledge: Must pass the Conversion - Private Pilot
  Licence – Aeroplane, (FAAPA) written examination on air laws and
  communications. Must be able to read, write and communicate in English
  or French.
  (4) Experience: Must provide proof of a minimum of 45
  hours pilot flight time.
  (5) Skill: No additional practical flight
  test is required.


What are some of your favorite flying and piloting related lessons or concepts to share with your non-pilot friends? My team at work is doing this thing where each person teaches something new every week. I want to teach them about flying (I'm a private pilot). I'm curious what you think are topics that people find interesting.
I want to skip explaining the physics/aerodynamics but instead focus on some lessons or concepts that can be transferred to other things in life.
For e.g

how everything is designed with safety / redundancy in mind,
single pilot resource management
checklists

What are some other cool ideas?

There exists a machine with which you can casually swim through the atmosphere to explore mountain tops, deep canyons, and vast expanses.  You need no special degree or unusual intellect to use it.  In fact, morons do it!  A little over 100 years ago it would have been called magic.  Today they are so common that many consider them a nuisance or necessary inconvience.
One type (there are A LOT of different types) is a million pound machine that can carry 500 people seven miles above the earth at 85% the speed of sound and cross entire oceans in mere hours.  How do you just not fall to your knees, mouth agape, in awe of such a thing??
Oh...because there are so many of them, and they're so safe, and so cheap to use that anyone with a few hundred dollars can bum a ride to anywhere on the planet while garbed in clothing a notch above underwear.
The fact is that we are living in SciFi land from the perspective of someone three generations ago.
And that's just airplanes.


What are these little things on the evacuation slide? I marked them with black circles. What are they for?

Source (modified)

@ratchet freak is correct. The protrusions are canopy poles, where the canopy in the evacuation slide/raft is propped up. The image below shows a canopy propped on them.

Image from tulmar.com

From the document:

  The canopy is supported in the center in 4 places by inflatable yellow “CANOPY END SUPPORTS” and “CANOPY CENTER SUPPORTS”, and supported along the sides by 14 numbered supports on the top of the slides inflatable structure.

Here's a closeup of the support from the same document.


Why does the A320 still have this old fashioned nose? Another answer stated that Airbus was less focused on just brand image, and more on aerodynamics, explaining the more rounded nose of it's 320 vs the 737's. But it still has flat cockpit panes which very conspicously NOT flush with the nose.

The same cannot be said of the A220, which is not much smaller, or even of the A350 which Airbus themselves developed.

Cockpit windows that sit flush with the fuselage can save a very small amount of drag, but they require large double curvature window panes. Manufacturing such panes is significantly more expensive and there was limited commercial availability for that product when the A320 was being designed.

You can see a few more examples of flat vs curved windows here: https://www.airliners.net/forum/viewtopic.php?t=754093

Cost and availability are a serious concern, as the A320 was already expensive compared to the competition. Paying more and risking delays if double-curved glass production couldn't be ramped up would not have been worth the savings. Airliners aren't just about performance, the very name "Airbus" hints that they're also a public conveyance.

In short, only the newest airframes get to make that small drag saving. Some older airframes had single curvature windows, which are between flat and double-curvature in complexity.

This has been explored in more detail in a broader question.


Why is there still a preference for turboprop airliners over the new regional jets? In the 1950s and in the early 1960s, jets were mostly available as fighter/military or big, long haul aircraft. Regional aviation was based primarily on piston aircraft that could operate in smaller airports.
When planes like the Boeing 727 and 737, Douglas DC-9 and Hawker Siddeley Trident came out, they finally brought the jet era to the regional aviation. But still, they were loud and inefficient. That's where the turboprops come in: they perform better than pistons and are suitable for small airports; they don't go as fast as jets, but are usually cheaper to maintain.

Given all that, most regional airlines started to use turboprops for their city links.

In the recent years, however, jet engines are getting quieter, more efficient and powerful. Embraer's Regional Jets and E-jets are out there; more recently, we've seen Bombardier releasing their CSeries and Embraer selling the first E2 units. Even though these planes are highly efficient, fast and suitable for short runways, airlines from countries like Brazil, Indonesia and India are still using turboprops as almost the entirety of their regional fleets. The development of modern planes like the ATR72-600 and the Bombardier Q400 shows how high the interest from airlines is.

The question is, what could be the cause of such preference? Why don't airlines prefer regional jets over turboprops, given their efficiency and speed and considering the tendency people have to "fear" propeller planes as old and untrustworthy?

Speaking of numbers, what would be financially better for a company: flying an ATR/Dash 8 or a modern jet like the E2/CSeries?

The simple answer is turboprops are more profitable on short stage lengths, say up to 400 miles or so, where the limited ceiling and slower speed are less of a detriment and the turboprop's better seat mile fuel burn is a bigger factor.  This allows lower ticket prices. Once you are getting out toward 1000 miles or more, it becomes worthwhile to go higher for both efficiency and weather avoidance ability, and jets start to become more profitable.

The -8 400 extends this somewhat and can almost match jets on moderate stage lengths on total trip time, so it bridges the gap between TPs and jets to a degree.  It's noise and vibration cancellation system helps this a bit by making the trip a bit less unpleasant.

There are other complications.  Depending on the market, pax may be willing to pay more for jet service on short trips, especially in affluent markets.  There are RJ operators in the US that run CRJ200s or 900s on very short runs that would be way cheaper served by TPs because their customer base demands jets and it's worth running those routes at razor thin margins to keep the customer base.

Other factors include things like maintenance sophistication.  Older TPs require less electronics-savvy technical expertise and a small operator having great difficulty retaining mechanics trained to figure out software based control systems will be attracted to simplicity.

One of the biggest drawbacks to the -8 400, and which in truth is killing it vs its ATR counterpart in sales, is the level of electronics sophistication is high compared to other turboprops, nearly jet-like.  When Canadian regional Air Canada Jazz acquired the -8 400, their -8 technical team was warned by their RJ technical team to get ready because the airplane was closer to a CRJ900 maintenance wise (systems run by black boxes vs hydromechanical components that any wrench turner can figure out) than an older -8.  The training level of the technicians becomes critical in achieving decent dispatch reliability.

TP vs C Series (soon to be renamed the Airbus somethingorother)?  Same thing. Depends on the mission requirement.  The C Series' competition is other jets, not turboprops.


How is Kool-Aid used as a visual cue to create contrast for an off-airport landing? In part 7-5-13 of the AIM, there is quite peculiar guidance given:

  g.  Off-Airport Landings.

  In the event of an off-airport landing, pilots have used a number of different visual cues to gain reference.  Use  whatever  you  must  to  create  the contrast you need. Natural references seem to work best (trees, rocks, snow ribs, etc.)

  (a) Over flight.

  (b) Use of markers.

  (c) Weighted flags.

  (d) Smoke bombs.

  (e) Any colored rags.

  (f) Dye markers.

  (g) Kool-aid.

  (h) Trees or tree branches.

How exactly is Kool-Aid going to assist in an off-airport landing?

Kool-Aid is usually brightly colored due to added dye. It comes in powdered form, and you would normally add water to make a solution.

If you have some in your aircraft in a suitable container (perhaps a paper bag), you can drop it on the ground during an overflight of an off-airport landing location. Hopefully the bag will burst on impact. When you return for an actual landing, the brightly colored powder can be a useful visual reference. This is especially important for landing with undistinguished surface cover such as snow.

Doing this successfully will take some practice, because you have to drop the right amount, in such a way that it breaks and spreads on the ground, at a suitable location, from some height that maintains your margins of safety. And if you're doing an off-airport landing in the first place, you probably have some other emergency going on at the same time.


What is the difference between Review and Analysis in DO-178C? In the context of DO-178C, what is the difference between review and analysis of the outputs of the software development processes?

Are they both the same?

No they are not the same.

Reviews are qualitative. They typically compare the artifact being reviewed to a standard using a checklist.

Analyses are quantitative. They could be functional analysis, data flow analysis, timing analysis, or other evaluation of the software artifact.

From DO-178C:

  6.3 Software Reviews and Analyses

  Reviews and analyses are applied to the outputs of the software
  development processes. One distinction between reviews and analyses is
  that analyses provide repeatable evidence of correctness and reviews
  provide a qualitative assessment of correctness. A review may consist
  of an inspection of an output of a process guided by a checklist or
  similar aid. An analysis may examine in detail the functionality,
  performance,  traceability, and safety implications of a software
  component, and its relationship to other components within the system
  or equipment.


Who decides how to "handle" an aircraft, with regards to severity of manoeuvres etc? Until Friday I'd flown only with EasyJet and Alitalia. In the last weekend, however, I took two Vueling flights and felt that the way the aircraft manoeuvred during the flight was very different when compared to EasyJet and Alitalia.

Take off seemed more "brutal", and we seemed to rotate much earlier, where the EasyJet or Alitalia flights will use more of the runway.
After take off, the airplanes did a lot of maneuvers during climbing. While EasyJet's planes usually do a variation of "turn, long climb, another turn", the Vuelings' performed a number of turns during climbing.
Landings, from the point of view of turning, are the same (as it should be). But after touchdown...it seemed to me the pilot maintained a higher rollout and taxi speed for much much more time, so that in both cases after the gear touching ground the plane reached the apron in a matter of seconds - and in both case the planes were yawing a lot when completing their landing roll and taxi, compared to the EasyJet or Alitalia flights.

In general the impression was that pilots were piloting in a more "sporty" manner (to use a motoring analogy), if you'll allow me the expression, and other passengers noticed it too.

So, question is: was it really just an impression? And if not, is there some kind of "direction" the airlines give to their pilots in how handle the plane?

Notes:

I'm NOT criticizing in any way the pilots. I know standards are
pretty high and is not the kind of job one can improvise or do
careless; I'm not saying or implying that they did pilot badly.
Airplanes are pretty the same, I've flown with EJ's A319 and A320,
both with winglet fences, and the Vueling's one was a brand new A320
with sharklets.
Air conditions were not extreme. In fact, I usually fly
Easyjet in winter in north Europe (MXP/LGW/CDG) in bad weather
conditions, while the Vueling flights were during clear days between MXP
and BCN.

Pilot in command, a.k.a. captain, has the last say in how the aircraft will be handled. However most of their decisions are driven by something:

Obviously performance of the aircraft. This is affected by weight (both cargo and fuel; aircraft only take the amount of fuel they need for the route they are flying and it makes a big difference) and weather (mainly temperature and head-wind).
Standard operating procedures (SOP). Certain operations can indeed be done in more than one way and each airline may indeed make slightly different choices. These are reflected in the recurrent pilot training.
Route flown. Airline flights are carried out under instrument flight rules, so the route is assigned by the air traffic control.

  Take off seemed more "brutal", and from a position slightly more at the beginning of the runways.

There is some freedom in choosing the take-off setting and standard operating procedure of different airlines may make different choices. Usually if the runway is long enough the engines are not set to full thrust, but so called “flex” thrust that is calculated sufficient for the take-off to limit wear of the engines.

What thrust and flap setting are possible is determined by weight, runway length, wind and temperature, but within the possible range, different airline may have different preference in their SOP (higher power or less flaps for faster climb v.s. lower power for less engine wear and more flaps for lower gear wear).

Noticeable difference might be in using “rolling take-off” where power is added immediately after turning on the runway without stopping there first. Whether it is possible depends on ATC, but some airlines seem to never do it.

  After take off, the airplanes did a lot of maneuvers during climbing. While EasyJet's planes usually do a variation of "turn, long climb, another turn", the Vuelings' did "a lot" of turns during climbing.

This depends on the departure route assigned by the controller. Note that even if flying the same route, the departure route could be different if different runway was used or if different routing was selected due to congestion (European airspace gets very busy at times and then the plane may wait or use different route).

  Landings, from the point of view of turning, are the same (as it should be).

Not necessarily. Arrival routes may differ similarly to how departure routes do. In fact even more so, because on arrival the aircraft are often vectored, that is get ad-hoc headings assigned by controller instead of flying standard route depicted on the chart, to achieve appropriate separation. On take-off the aircraft simply wait on the ground until the previous aircraft is far enough so it's not needed often.

  But after touchdown...it seemed to me the pilot kept an higher speed for much much more time, so that in both cases after the gear touching ground the plane reached the apron in a matter of seconds

Again there can be differences in SOP regarding preferred auto-brake setting, but usually every pilot will want to vacate the runway as soon as possible, so it seems more like difference in what exits were available.

It might have also been difference in the aircraft. There was some talk about Airbus implementing “brake to vacate”, where the computer handles the brakes so the aircraft slows down just before the next suitable turn-off, on the new A320, but I found no reference whether they already did.

  and in both case the planes were swinging a lot.

The vertical tail acts like a weather-vane and the thrust reversers reduce lateral stability, so the aircraft always needs some directional corrections during landing.

In the air the aircraft turns by banking, so you don't feel any lateral movement. But on the ground it can't and due to the speed you feel even very slight turns.


How are bids packages and awards generated? There probably is no short answer for this. Crews out there, how do you bid and how are you rewarded? Are you always satisfied with your lines? Can someone also explain in brief from a system point of view, if you happen to be a crewscheduler. Thanks

This differs from airline to airline, at a large ME carrier the staff is divided in groups based on their personality. People from each group are randomly assigned to flights. Then there is a list where you're at a certain position, with each flight you take you move one spot higher on the list. The higher you are on this list the more they will take your preference for a flight into account. Lets say that this list has 7 positions, once you've hit the top you are moved back to the bottom of this list. Then with each flight you're going one step up in the list again. So after each 7 flights you have the flight of your preference. But say that you're almost at the bottom and file a preference for a very unpopular flight then you have a high change they will schedule you on that flight.


Has there been a recent change in the airspace configuration at KFYV-- Drake Field near Fayetteville AR? Has there been a recent change in the airspace configuration at KFYV-- Drake Field near Fayetteville AR?  If so, where can we find an official description of that change?

KFYV -- Drake Field airport at Fayetteville Arkansas http://vfrmap.com/?type=vfrc&lat=36.005&lon=-94.170&zoom=10

(Memphis sectional chart, western portion of north half)

A sectional chart dated April 13 2006 shows a class D circle with a large E4 (dashed magenta) extension to the south, but on the current sectional chart (effective March 28 2019) the area projecting to the south is now much smaller and is class D rather than E4.

Has there been a recent change in the airspace here?

If so, what is the official FAA source that describes that change?

I do not see the airspace configuration as shown on the current sectional to be reflected in the August 2018 edition of the FAA's "Airspace Designations and Reporting Points" document ( https://www.faa.gov/documentLibrary/media/Order/JO_7400.11C.pdf ) , or in the more recent amendments given here https://www.faa.gov/air_traffic/publications/airspace_amendments/

The Class D airspace is described on page D-112 of the "Airspace Designations and Reporting Points" document, and the E4 airspace is described on page E-206.  The description matches what I see on the 2006 sectional chart.

Is the current sectional chart simply wrong?

A little more googling has provided an answer -- on 12/10/18, effective 2/28/19, the extension was greatly reduced in size (and the remaining bit converted to class D) due to the decommissioning of the Drake VHF omnidirectional range (VOR) navigation aid -- see https://www.federalregister.gov/documents/2018/12/10/2018-26498/amendment-of-class-d-and-e-airspace-and-revocation-of-class-e-airspace-fayetteville-ar

I'm not sure why that airspace change was not reflected in any of these documents-- https://www.faa.gov/air_traffic/publications/airspace_amendments/

Actually, it was there, I just didn't see it because they mistakenly used the abbreviation "AK" not "AR" for Arkansas in the table.

Nothing more need be said here--


How close would another aircraft have to fly to warrant a sudden big altitude drop to avoid collision This morning I read that mulitple people got (light) physical injuries after a passenger flight had to forcefully drop its altitude quickly in order to avoid collision with a fighter jet. The news article stated that it was flying at a  "safe" distance of 1,000 metres for a visual inspection, and that there was no danger at all. Although some other sources state that the distance was only down to a hundred meters
To me (someone who knows next to nothing about flying) a distance of one kilometer sounds pretty close for two planes to fly at (seeing the speeds planes travel at). The article states that this is "in accordance with international standards", but from this answer I understood that 3 to 5 miles (4.8 to 8km) is the general distance. However that answer also states that in a "Military Operations Area" this may not be the case (which this area might have been in, but then I feel like it wouldn't have mattered that it was "in accordance with international standards", as those don't apply then anyway).
That said, are there any alarms or warnings that start going off when another aircraft gets so close to warn the pilot of possible collision, or is a pilot trained to undertake action based on what his/her visuals/flight data are telling him/her at the moment? (I have read before that measuring a distance by visuals is very hard in open air due to there being no reference points, so I think it is unlikely that a pilot would act up on that alone). What is the protocol for a pilot suspecting the possibility of a mid-air collision?

It seems that this incident is also a bit of a political issue. I am not trying to discuss if everyone took the right actions here, and what the intentions of the parties were. Just interested in the protocol behind making such a drop.

Most modern aircraft are equipped with TCAS (Traffic Collision Avoidance System) which is a last resort to avoid collision if all other safety nets have failed and two aircraft have gotten too close.
A TCAS can generate an RA (Resolution Advisory) which is a distinct message instructing the pilots what to do - typically either "CLIMB" or "DESCEND". When an RA is generated, the pilots have to comply with it immediately, regardless of all other instructions, unless it directly puts the aircraft in danger. In case of two conflicting aircraft, the TCAS system of each aircraft will communicate with the other, so for example, for two flights on converging courses, one will get a "CLIMB" instruction and the other a "DESCEND".
As for timing:

The maximum generation time for an [...] RA is 35 seconds. The time scales are shorter at lower altitudes (where aircraft typically fly slower). Unexpected or rapid aircraft manoeuvre may cause an RA to be generated with much less lead time. [...] The effectiveness of an RA is evaluated by the ACAS equipment every second and, if necessary, the RA may be strengthened, weakened, reversed, or terminated.

From SKYbrary
Essentially, this means that an RA will only be generated if two aircraft are calculated as being very close to colliding (within 30 or so seconds of collision). Note that the actual distance between the two aircraft does not matter in this regard - calculations are based on "time until impact". Two aircraft on slightly converging courses, closing slowly, can get much closer before an RA is triggered compared to two fast aircraft meeting head on.

As for the specific incident you are talking about, it is unclear if a TCAS RA was generated. Normally, fighters intercepting an aircraft will turn off their transponder (at least partly) to disable TCAS, with the specific purpose of avoiding such alerts (since they intentionally want to fly close to the other aircraft).
Even if we consider the "1000 metres" claim to be correct, it is not possible to say if that is "too close" or not. If we are talking 1000 metres vertically, that is more than 3 times the normal required separation of 1000 feet. However, 1000 metres horizontally would, in many (but not all) cases, be too close.


What does "transition of glideslope intercept waypoint" mean in the 737 FCOM? In the Boeing 737NG FCOM, I've read this statement:

VNAV mode is terminated by any one of the following:

selecting another pitch mode
glideslope capture
reaching end of LNAV route
transition of glideslope intercept waypoint if G/S is armed
crosstrack deviation exceeds twice the RNP value during PTH descent for
an active leg with a database vertical angle and LNAV not engaged

In the event of glideslope intercept waypoint transition, VNAV can be re-engaged.

What does "transition of glideslope intercept waypoint if G/S is armed" mean here?

As a generic (non-737 specific) answer, it means that when the Flight Director is armed to capture an ILS glideslope, the VNAV flight director mode, being a vertical path based on baro altitude, is cancelled once the aircraft passes through a waypoint that the RNAV system calculates to be the geographical intercept point of the ILS glideslope beam (the intercept waypoint) because the Flight Director is expected to capture and track the ILS glideslope and RNAV/VNAV guidance is no longer required.


Why does the C-2 left inboard stab not have a rudder? As visible in the following picture

(wikimedia.org)

the left inboard stabilizer doesn't have a rudder but the right one does.

Wikipedia on the C-2 describes it as:

  The C-2 has four vertical stabilizers, of which three are fitted with
  rudders. A single vertical stabilizer large enough for adequate
  directional control would have made the aircraft too tall to fit on an
  aircraft carrier hangar deck. The four-stabilizer configuration has
  the advantage of placing the outboard rudder surfaces directly in line
  with the propeller wash, providing effective yaw control down to low
  airspeeds, such as during takeoff and landing. The inner-left
  stabilizer lacks a rudder, and has been called the "executive tail",
  as it has nothing to do compared to the other three.

The rationale explains the primary design, but no explanation for the "executive" tail. Can anyone explain why the C-2 is designed this way?

The C-2 was developed from the E-2 Hawkeye (the one with the big radome).

The radome disrupts the airflow behind, hence the need for the inboard fins (source), they help stabilize the airflow and act as fences for the outboard fins.

Those inboard fins were not needed for the streamlined radome of the earlier E-1 (shown below).

Alternatively they could have extended the fuselage length, but they didn't go that way. The three rudders provide sufficient control in single engine operation, yet are overpowering when both engines are working, which caused early control problems and stability augmentation had to be implemented (source: University of Tennessee, MS thesis, 2002).

The E-2 and C-2 feature rudder authority limiter as part of that augmentation (C-2A flight manual).

And apparently the rudder authority is sufficient enough that the E-2 can turn (to remain in orbit) while keeping the radome fairly level (source).

As to why the right one is the one with the rudder, I don't know. The engines are not handed (video). But as far as I know, a normal force on a laterally placed fin does not change the moment arm around the yaw axis, but I'm happy to be corrected.

Development information on the E-2/C-2 is scarce, so I hope that's sufficient for the time being, I tried to find as good sources as possible.


What is that invisible bump in the air called that occurs after completing a 360 degree turn? Does that bump you feel after completing a level 360 degree turn in an airplane have a proper name? I've heard it called an "attaboy bump", but obviously thats not a proper name.

My understanding is that the bump occurs when a properly executed level 360 turn overlaps the disturbed air caused by the same aircraft's flight path into the turn.

It's your aircraft's wake, as in wake turbulence.


Would "Mad" Mike Hughes' steam-powered rocket have been certified airworthy by the FAA? Daredevil 'Mad' Mike Hughes died after his homemade rocket crashed on 22 February 2020. The cause appears to be the premature deployment of the parachute used for a safe return. He was hoping to reach 5000ft.

In the U.S., Title 14, Code of Federal Regulations, Subchapter F, Part 91.7 states:

  "No person may operate an aircraft unless it is in an airworthy
  condition"

The FAA defines an aircraft as "A device that is used or intended to be used for flight in the air" and has extensive information on certifying home-built or experimental aircraft. The original rationale, I presume, being that an aircraft is a danger not only to its occupants but people on the ground too.

They also say

  the owner or operator of an aircraft is primarily responsible for
  maintaining that aircraft in an airworthy condition

... but what is not made clear is whether it is an offence to operate fly your own aircraft without FAA airworthiness certification.

With regard to Hughes' home-built rocket, the FAA definition of aircraft surely qualifies this device as an aircraft, (although,  owing to its speed, not an ultralight which have their own waivers). Further, there was no intent or pretence to go to space, so the SpaceX / NASA rules don't seem to apply here.

It seems to carry no registration, nor the mandated "EXPERIMENTAL" marking one would expect if it were - however, it is noted that in the US an aircraft does not have to be registered to be certified airworthy (although they usually are).

Should this sort of aircraft fly with an airworthiness certification? And if it didn't, why not?

NOTE - this is neither the place nor the time for a discussion of the wisdom of Mr Hughes' venture.

source

.

Interesting topic.  Rockets and spacecraft are still highly experimental vehicles and are recognized as such under 14 CFR §1200.  The laws, liabilities, and regulations for private spaceflight are largely uncharted territory at this point, though §1266.102 requires all participants aboard the ISS and NASA launch vehicles to sign a liability waiver prior to flight.  Essentially, in the eyes of the law, you’re on your own in doing this and if your injured or killed, neither you nor your estate can hold any participants in your cosmic ordeal liable.  Given that many flat earthers view NASA as the enemy of their efforts, any laws in regards to spacecraft certification would probably be viewed in a negative light and disregarded.

Using §91.7 here is pretty nebulous as there is no definition or standard here for airworthiness of such a craft.  These guys were testing an experimental vehicle at a remote site far away from other persons or property and flying only a single flight crewmember.  There’s really no law saying you can’t take a risk like that under those conditions.


How do airliners cross the ocean without GPS? How do airliners cross the ocean without GPS?

Do they use dead-reckoning or are there navigation aids floating out there?

Well, most airlines do cross the ocean with GPS in today's world.

That being said, most (if not all) transcontinental airliners, and many flying domestic routes as well, have what's called an inertial navigation system (a form of dead-reckoning where gyros and accelerometers are used to compute changes in position). The INS feeds into the flight management computer which is used to cross-check the GPS position, and can be used as a primary navigation source should the GPS signal be lost or corrupted.

Prior to GPS, inertial navigation was the primary means of navigating across oceans. However, a great many airplanes did cross oceans before INS... with varying success. The general idea was to use a combination of dead-reckoning, radio beacons where you can find them (small islands and coastlines), the sun (with the help of a sextant) during the day, and the stars at night. Hopefully, this puts you in position after some period of time to pickup ground-based navigational aids, or to identify a coastline. This actually works pretty well if your wind estimates are good, and the margin for error is high enough. As DeltaLima points out, long-range radio navigation systems also started to emerge around World War II (LORAN and Decca) which had a much greater range than previous radio beacons, and therefore decreased the amount of time required to fly by dead-reckoning alone. By the time inertial navigation became prevalent in the 1970's, airlines were already providing reliable transcontinental passenger flights every day.

Another possible outcome is that your plane is lost in the ocean, never found, and the Discovery Channel funds an expedition to look for you 75 years later.


Is a certificated pilot in a rear seat with no access to flight controls a safety pilot or a passenger? To be considered a safety pilot, must the aviator in question be able to manipulate the flight controls, or is see-and-avoid responsibility sufficient?

Asked another way, if the PIC wants to fly under simulated instrument conditions to maintain currency in a Cessna 172, is the lone pilot seated in the rear a safety pilot or a passenger? Did the PIC bring along one safety pilot or two?

After looking through the FAR's, the answer is no, the rear passenger seat cannot be occupied by somebody claiming to be a "safety pilot".

FAR 91.109(c):

  (c) No person may operate a civil aircraft in simulated instrument flight unless—

    (1) The other control seat is occupied by a safety pilot who possesses at least a private pilot certificate with category and class ratings appropriate to the aircraft being flown.
    (2) The safety pilot has adequate vision forward and to each side of the aircraft, or a competent observer in the aircraft adequately supplements the vision of the safety pilot; and

(Emphasis Mine)

So the safety pilot basically has to be able to access the controls and have vision that supplements the pilot, meaning must be able to see as well as the pilot position would.


What was the forensic process underlying the recent news regarding MH370 debris? On or about July 30, 2015, the initial news could have been worded like: "debris appears to have come from a Boeing 777". As the story evolved, additional details emerged such as the wreckage being part of a 777 flaperon, before being decisively announced.

My question is: what was the forensic/investigative process which would have produced the initial speculative-sounding announcement associating the debris to a 777, before ultimately becoming the more definitive statement?

To put it another way: what steps had investigators taken up to the point of each announcement, and how was the debris recognized very early on as part of a 777 without actually being confirmed as such? Is it investigator experience? If initial identification was made by part numbers, why would there have been any doubt in the announcement?

If you bring an NTSB investigator a piece of 2024 sheet aluminum with zinc chromate primer and a urethane topcoat all they can tell you is "It's 2024 sheet aluminum, with some paint on it." - BUT if you bring them a piece of 2024 aluminum riveted to a  structure that looks like this:

and tell them "I found it on an island in the Indian Ocean" they can infer  lot more.

In this particular case they've found some debris, and they know a few things:

The debris was found in an area where it's reasonable it could be part of MH370.
The location isn't conclusive in and of itself, but it's certainly a factor that strongly implies this could be part of the missing aircraft.
The part LOOKS like it came off an airplane.
It's aircraft aluminum, riveted to a skeleton that gives it an airfoil shape. That warrants further investigation by itself (even if we didn't lose an airplane in that area recently it's clear that some part fell off some airplane at some point in time, and investigators generally want to know which airplane had bits falling off).

That leaves us with the question Could this part have come from the airplane we lost?  which is the stage we're at now, and there are many ways to make this determination.

You might get lucky and recover the aircraft ID plate, or a chunk of the tail with the N number.
There's confirmatory testing to be sure it's not a well-perpetrated hoax, but these are pretty definitive identification elements. Unfortunately that's not the case here, so we move on.
If you recover what appears to be a control surface you'll usually find a manufacturer stamp somewhere on the part, or a serial number plate. They'll certainly be inspecting this debris to look for that kind of data tag. (The data tag below is from a Piper control surface but Boeing probably uses similar plates).

If you don't find a data tag maybe there's airline livery on the debris.
This at least lets you know whose plane you've found, but that's not applicable here as the debris in question appears to be painted basic white.
Failing all of that you compare what you've found to manufacturer's drawings of the aircraft you think it came from and see if the dimensions match any parts or sections of that aircraft.

There are other possible steps and confirmatory testing involved (metallurgy, mass spectrometry on the paint, etc.) to determine if it's likely this part came from the aircraft you think it did, but that's getting into the territory where you'd be better off signing up for training courses in accident investigation.


Are general relationships between MTOW and OEW valid for novel configurations? I am a student in mechanical engineering with a passion for aerospace engineering, especially airplane design.

However, coming from a more mechanical than pure aeronautical background, I feel that even now, doing a masters in what is essentially conceptual airplane design, I am lacking a certain foundation in the methodology of airplane design.

To remedy this I have recently obtained the very well-known books on airplane design by Roskam and Raymer and have started working through these books.

My question is: In the modern age of airplane design, where we are starting to get interested in more novel and radical configurations, are the approaches presented by Roskam and Raymer (and I am sure there are others authors) still valid?

To summarise this design methodology I am talking about:

  Determine payload weight
  Guess aircraft maximum takeoff weight
  Estimate fuel fractions for different mission segments from historical correlations
  Calculate tentative empty weight
  Determine allowable empty weight by taking advantage of the fact that, historically, there is a logarithmically linear relationship between maximum takeoff weight and empty weight
  Compare tentative empty weight and allowable empty weight, if the values are too different, guess a new value for maximum takeoff weight and continue this iterative process until convergence

This design procedure uses historical correlations in the fuel fraction determination and through the historical trend in relationships between MTOW and OEW.

Is this approach still valid for novel configurations?

Most importantly, is it known whether this logarithmically linear relationship between MTOW and OEW independent on configuration?

Many studies and presentations you will encounter about radically different configurations with much higher performance are the aviation equivalent of car commercials. Someone tries to get attention in order to get published, or she/he needs to convince investors to fork over their money.

Trust me, the aircraft designers of the last century were no idiots. They had the luck of living in a time when it took only a few years for aircraft designs to become obsolete, so they could go through the whole design process many times and apply what they had learned before.

Someone graduating from university today will be lucky if she/he gets the chance to go through every step of a major design process even once. I myself have brought three aircraft into the air and consider myself very lucky. I had colleagues who retired without ever having seen one of their many projects take off (literally).

The consequence of this is a very mature industry which has found an optimum configuration for most purposes already and is only tinkering with the details. Add to this an ever increasing thicket of regulations which have grown on the experience from existing designs. Sure, the progress in computer control is impressive, and engines get better all the time. Manufacturing precision is ever increasing, and materials still become better and more consistent. But overall, we still build aircraft like we did a generation ago, and I do not expect this to change radically in the future.

What impacts the design process most is certainly the incredible precision of simulation software, which allows to see details which remained hidden in a wind tunnel or a strength test. Things which had to be done consecutively can now be done in parallel, and the precision of knowledge at an early stage of a design is much higher than before. But at the same time aircraft become ever more complex, so the advantage of better simulation is eaten up by the increase in complexity. Add to that the fact that mostly beancounters will have the last word, where before engineers could determine how the work was done, and you will understand that the level of preparatory work is shockingly inadequate in modern aircraft companies. Many of the avoidable early mistakes will require late, expensive fixes (but by that time the stingy beancounter has left the company with a huge bonus for the money he bragged to have saved).

The design process is still the same, and where before the experience of a few people helped to find an overall optimum, large, integrated teams will together determine this optimum. The inexperience of the participants will only show up in delays, when the iterative design cycle needs to be repeated more often than anticipated, but the result will be of high quality - really bad designs are a thing of the past. But cutting corners will still have consequences, so small annoyances will still plague new designs. Consequently, most of the engineering work will involve ironing out these annoyances or retrofitting new systems to existing airframes.

To answer your specific question: Yes, the relation between OEW and MTOW will still hold in the future, and radically new configurations will show an advantage only on paper, before they have been thoroughly designed and test-flown. Better materials and methodologies will help to improve the ratio between OEW and MTOW, but this advantage risks to be eaten up by the desire to add bells and whistles everywhere.


How does altitude affect the TAS and thrust of an electric fan powered aircraft? I'm confused about the relation between IAS, TAS, thrust, and shaft power, for an electric application. Yes, higher air is thinner, and thrust goes down due to higher airspeed. What I've researched uses only air breathing engines for calculations.
Gas turbines either are limited to lower altitudes or higher altitudes with high speed, to intake enough air to maintain combustion. The other limiting factor is they have very strict maximum rpm. Modern turbofans do not have a variable transmission to counteract this. The same concept applies to electric motors, to a lesser degree.
For example, an electric driven ducted fan has a tip speed of Mach 0.85 and was set to maintain the same power output of say 50kw no matter the altitude.

What would happen to the TAS, IAS, thrust and the shaft rpm of the motor as well as tip speed of the ducted fan as the altitude increases?

Is the power necessary for an increase in TAS and a constant IAS the same up to the point where the increase in rpm (less load) due to thinner air causes the fan blades to see supersonic tip speeds?

If an aircraft can fly at 60 knots with 50 kw at sea level, does that mean at 50,000 ft it can realistically fly at 185 knots TAS for the same given power? (I used this calculator).

Also, how does thinner air affect static thrust?  Is the same thrust maintained as long as the same amount of power is given to spin the fan?

The Helios was an electric powered prop driven aircraft that achieved an altitude of over 96,000 feet and maintained it in level flight for more than 40 minutes.

as altitude increases

You maintain wing lift with constant IAS until the wing airflow approaches the speed of sound (TAS increases).  Shaft power output must increase to spin prop faster to maintain thrust or... changing prop pitch is helpful instead of increasing rpm.  This helps avoid the "sound barrier" for the prop.

as motor rpm increases

Even when not limited by supersonic prop tips, increased engine bearing friction from higher rpm requires a greater power draw.  Again, the ability to vary prop pitch is enormously helpful to maintain optimal prop AOA as TAS increases.

can I fly with the same amount of power at 50,000 feet as I can at sea level

You can get a lot closer by designing your aircraft to fly at 50,000 feet by:
 1.  Reducing wing loading by removing weight
 2.  Increasing wing aspect ratio and/or increasing wing area
 3.  Increasing the **area** of your prop so you can push more air at the same rpm.

With props, you must compensate for thinner air, but higher rpm is not the only way.


Why are some modern military trainer aircraft so bulky? Modern military trainer aircraft are a lot wider and bulkier than the previous generation. Especially the canopy looks oversized.

You can see this in the Boeing/Saab T-7 Red Hawk, Alenia Aermacchi M-346 Master (developed from the Yakovlev Yak-130) and Hongdu JL-10.
Development for these aircraft was started in the late 90s / early 2000s. All of these aircraft have a secondary light combat role. They are supersonic capable.
The seating position is staggered, probably so that both pilots (or student / instructor) have good visibility. This might explain the enlarged canopy. The wider cockpit is likely more comfortable and enables longer missions as well.
Additional avionics and increased fuel capacity may explain the overall increase in volume.
There seem to be some underlying reasons for these designs, but they are unclear to me.
What prompted these changes in the designs?

You mentioned the oversized canopy for two, staggered for better visibility, and really that is the main feature that stands out.  Consider that trainers are typically quite a bit smaller than their full combat brethren and this feature is even more out of proportion.  Also, full sized combat 2 seaters generally have a Weapon System Officer in the back seat, so good forward visibility isn't as crucial as it is in a pilot trainer so less upward stagger of the back seat is needed.
The human body doesn't scale up and down like an airplane design, it is the constant that must be designed around. Think about it, you are fitting two 6 foot tall people in a fairly small plane vs often one in a larger plane; naturally the space for the bodies will be a much larger overall percentage of the size of the  trainer.
If you were to compare a 2 seat trainer next to a larger 2 seat combat aircraft like the F14 Tomcat, (with its huge engines...) I think you would find that the cockpit areas are actually pretty similar in size.  They are just more pronounced in the smaller plane.
Other than the cockpit area they really aren't "bulky" at all.  In fact the two pictured are VERY compact and streamlined, by just about any standard.


Why Apollo 11 was launched in summer? (Performance question) The question could seems stupid, but i think that best moment to launch a rocket is when temperature is lowest in order to achieve the best performance in a reaction engine. I do not know if there is some explanation to this or is just because that performance degradation is irrelebant.
Thank you for your time.

The temperature of the environment doesn't have a significant impact on the performance of a rocket engine. Air breathing engines have better performance in cold air because the mass density is higher at a given pressure, which allows them to ingest more air, and because the thermodynamic efficiency of a heat engine increases when the temperature of the cold side decreases.

A rocket uses oxidizer from a tank, and the thermodynamic cold side temperature is the temperature of the propellant before it gets burned. Thus, atmospheric temperature doesn't change rocket performance like it does for air breathing engines.

Remember that rockets aren't pushing against the air, they're pushing against their own exhaust. Atmospheric pressure slows down the escape of the exhaust, reducing thrust. Rockets will produce more thrust in a vacuum than they will in the atmosphere.

The main concern for timing the launch of Apollo 11 was making it happen as soon as possible, both to beat President Kennedy's promise to land a person on the moon before the end of the decade, and to beat the USSR to the moon.


Why are there 40 737 Max planes in flight when they have been grounded as not airworthy? Many countries have already grounded 737 Max planes and as of Mar 13, 2019 the FAA have stated:

  The FAA is ordering the temporary grounding of Boeing 737 MAX aircraft (PDF) operated by U.S. airlines or in U.S. territory. The agency made this decision as a result of the data gathering process and new evidence collected at the site and analyzed today. This evidence, together with newly refined satellite data available to FAA this morning, led to this decision.

Source FAA Statement on Boeing 737 Max

So why are there currently 40 737 Max planes in flight according to FlightAware?

Who would be liable should one of these flights crash on takeoff, potentially over a densely populated urban environment?

Most of them are probably on a ferry flight. The EASA directive allows 1 transfer with up to 3 flight legs without passengers.

Some of them are travelling between countries where they are not grounded.

When a commercial plane crashes, the airline is liable, unless it can prove that the manufacturer is at fault.

I revisited the FlightAware search for B737M today (March 15th), because I was curious how the picture has changed. Same time of the day, just 1 day later:

There is now much less B737M traffic in the US, none in EU, slightly less in Asia, and increased traffic in Africa. That would be coherent with what I answered yesterday, but I was also curious about @Ben's claim that the FlightAware data is not correct. Now this is what I found:

The search in FlightAware identified 26 flights as B38M. Cross checking with FlightRadar24 delivered:

1x 737 MAX 8
18x 737 other than MAX
1x 787-9 Dreamliner
6x not found

The only 737 MAX was - according to FlightRadar24 - AAL9663 from Miami to Phoenix.

I am not sure what exactly FlightAware is showing. My guess is that they are showing the types that are planned to execute the flight.


On average, how many overhauls will thrust reversers have in their lifetime? How many overhauls will a wide body aircraft composite thrust reverser undergo in its life? (not including damage, etc.)

The answer varies from aircraft to aircraft. The newer varities such as the A380 go for a overhaul in about 1200-1500 hours, whereas the B777's go once in 1600-2000 hours of service.When an aircraft goes to overhaul, only then the thrust reversers go to overhaul, because they are an important component of the engine of modern day aircrafts. Though we do not know when will an aircraft retire, so it i difficult to come at a concrete result. But, talking about B747, many airlines are retiring them at the age of 40 years. So, 40 years = 350400 hours. 350400/2000 = 175(Approx.) So, for a B747 the answer should be like 175, and this does not necessarily implies to other aircrafts as well.


What exactly do "captain", "pilot", "co-pilot" and "first officer" mean? I know the co-pilot sits beside the pilot. But it's not clear for me, who is the captain and who is the first officer?

And where they are sitting during the flight? Who is in right seat and who is in left seat, and probably who will seat behind the front seats for an aircraft with more than two flight crew?

Capt left, 1st officer or copilot right. On older airlines with a flight engineer, he is behind and is called 2nd officer.

It's the same as a ship.  Capt is boss, 1st officer is second in command, 2nd officer if on board is 3rd in command.

Capt always starts the engines and taxis the airplane since most airliners only have a steering tiller on the left, and FO usually handles radios and checklists, FMS programming etc when on the ground.  FO, if it's his/her turn to fly, only controls the airplane from the start of the takeoff roll until completion of the landing roll.

On a pairing (sequence of trips over 2 or 3 or 4 days), capt and FO normally alternate on each leg of the trip as pilot flying with the other as pilot monitoring.  But as I said, if FO is PF for a particular leg, he/she will still do the radios until the start of the takeoff roll, then takes control of thrust and stick once the capt has lined up, upon which capt looks after comms/FMS/button pushing, until completion of the landing roll, when the FO hands control of the airplane back to the capt and the FO (who only has rudder pedal steering and can't make sharp turns) takes over the radios again.

On an older airliner with a Flight Engineer/Second Officer, that person is type rated on the aircraft as a pilot but never actually flies the plane until he/she moves up to right seat as FO.  So in the old 3 crew days a new pilot would be hired as a Flight Engineer in an airline with only 3 crew aircraft and might go several years in the 3rd seat before actually flying the plane, or if upgrading from 2 crew to 3 crew in the same airline.

Up until the 60s you also sometimes had a 4th crew, a Navigator.  Don't think there were any Navigators left by 1970.


Why does this GPS approach say "RADAR REQUIRED"? As I was looking at the approach charts for KCXY while answering this question, I realized that the GPS "overlay-style" approach to RW8 also requires RADAR.

Since the HAR VOR isn't even shown on this Approach, and it has an IF, why should RADAR be required?

Note that the RNAV (GPS) RWY 26 approach to this airport does not require radar.

The immediate reason seems to be that for RNAV approaches that start at an IF (Intermediate Fix) - not an IAF (Initial Approach Fix) - radar is required per the ATC orders (4-8-1h):

  issue approach clearance [...] only after the aircraft is:

  Established on a heading or course direct to the IF at an angle not greater than 90 degrees, provided the following conditions are met:

  [...]

  (b) Radar monitoring is provided to the IF.
  (c) The SIAP must identify the intermediate fix with the letters “IF.”

The RNAV 26 approach that you mentioned does have an IAF, so according to the same rules radar isn't always required for it.

You might now ask, why is radar required for RNAV approaches that start at an IF? Because, it doesn't have an IAF.

The next question is why doesn't it have an IAF? Probably because of higher terrain north of the approach corridor? Or maybe (as per @Jonathan Walter's answer) there is sufficient Radar coverage to vector to the IF, so it doesn't need an IAF.


What are the legal issues for an Uber or Lyft type model for ride share on General Aviation aircraft in the United States? Is it possible for an Uber or Lyft type service to operate that allows pilots with small aircraft to share a ride under current FAA regulations? I personally don't see how this could operate under 14 CFR 91, but maybe under what's allowed under 14 CFR 135.

I haven't been able to identify exactly what companies are trying, but I've been hearing that something like Uber for small planes is under development. This has caused great skepticism on my part that a company could accomplish this because of the regulatory requirements involved.

Depending on how much detail you want, you can read the legal ruling in Flytenow Inc. vs FAA, which is the most recent and highest-level ruling on general aviation flightsharing. The Supreme Court declined to hear an appeal.

Essentially, Flytenow wanted to let pilots find passengers willing to share the costs of a flight. They emphasized repeatedly that all decisions about if and when to fly, the route to take etc. would be made by the pilot, not the passengers. On the other side, the FAA said that by advertising for passengers, pilots would be holding out and that makes it a commercial operation. There were plenty of arguments on both sides and ultimately the courts decided that the FAA was acting consistently with previous decisions and regulations.

Flytenow made three legal arguments, all of which were judged invalid on appeal:

Advertising for passengers is protected free speech under the First Amendment
Private pilots' equal protection rights under the Fourteenth Amendment are infringed if they can't share costs
The FAA's ruling was vague

If you read the court's decision, you can see that they basically agreed with the FAA that protecting passengers justifies limiting what private pilots can do:

  The FAA’s distinction between pilots offering expense-sharing services
  on line to a wide audience and those offering expense-sharing services
  to a limited group is justified: holding out to the public creates the
  risk that unsuspecting passengers, under the impression that the
  service and its pilots lawfully offer common carriage, will contract
  with pilots who in fact lack the experience and credentials of
  commercial pilots.

To put it even more simply, the basic difference between Uber and Flytenow is that the FAA believes that the general public can identify a bad driver, but not a bad pilot. That's the fundamental reason for having commercial licenses, part 135 etc.


In case of transponder failure, can I use my ADS-B out (Stratus II) serve as a back-up? When the transponder fails, would ATC pickup my altitude response from my Stratus or any other ADS-B out instead? Is it legal to do so?

The Stratus does not broadcast. It recieves only. So that is no help.

If you had a stand alone UAT ADS-B transmitter. It might continue to broadcast your altitude if your transponder failed. The UAT requires an altitude input and it must be from the same source that your transponder gets it. Sometimes that gets wired directly from a 2nd output of your altitude encoder (bypassing the transponder which gets it from the 1st output) in which case it would continue to broadcast altitude. Sometimes the altitude wiring goes from your encoder to your transponder, then the transponder has an output that sends it to your ADS-B UAT. In this case it might fail if the transponder fails.

It might be useful to know that the ADS-B transmitter must broadcast your current transponder code (1200 for vfr). The UAT generally senses it automatically as the transponder broasdcasts it so you don't need to set it in 2 different controls. But if your transponder fails, it won't sense the code and may go into a fail mode on it's own (not sure about this though).

The advent of ADS-B brings no relaxing of the regulations regarding the requirement of using transponders.


Do high-wingers have dihedral? I know that high wingers have an inherent dihedral effect.

Are there any examples of high wing aircrafts with a dihedral?
If so, what is the reason behind it?

High wing planes typically have less dihedral than an otherwise comparable low wing design, because of keel effect: they have more righting moment for a given dihedral angle because the fuselage hanging below the wing increases pressure near the wing root on the low side when a bank induces slip.

The value of the dihedral can be low enough that the wing may look flat (Piper Cubs and Taylorcraft look flat, to me), but if you build a high wing airplane with genuinely zero dihedral, the wing will appear to droop (take a look at period photos of Lindbergh's Spirit of Saint Louis).

Dihedral is present in nearly all high wing aircraft, for the same reason it's present in nearly all low wingers -- because it tends to support or raise the low wing when a bank without coordinated rudder causes side slip.  This produces lateral stability, which in turn makes the airplane easier to fly.


What is the difference between CAN and ARINC? I want to know the difference between CAN and ARINC, I'm confused about their usage.

For example, the communication between the cockpit and the controllers is done using ARINC protocols. And the data transmitted by probes to the controllers goes over CAN. Why use a different protocol in each case? When is each protocol used?

the communication between the cockpit and the controllers is done by using Arinc protocols. And the data transmitted by probes to the controllers is done by CAN.

That depends very much on the aircraft type.

  And when can we use each one of them (Arinc and CAN)

When you design your own aircraft you get to choose.

CAN stands for Controller Area Network. CAN is a bus standard designed to allow microcontrollers and devices to communicate with each other in applications without a host computer. It has its origins in the automotive industry.

ARINC stands for Aeronautical Radio, Incorporated. ARINC is an organisation that amongst other activities produces technical standards for avionics and provides services to aircraft operators.

Amongst the ARINC standards there are a number addressing data communications between avionics components. Most widely used is the ARINC 429 standard which describes an avionics data bus. ARINC 429 allows a single transmitter to communicate data to up to 20 receivers over a single bus.

Comparing CAN bus to ARINC 429:

Cable

CAN: STP or UPT, possible to implement on fiberoptic cable
ARINC 429: STP

Speed

CAN: 1 Mbit/s (high speed) / 125 Kbit/s (low speed)
ARINC 429 100Kbit/s (high speed) / 10-14 Kbit/s (low speed)

Directionality

CAN: bi-directional, connected units can send and receive on the same cable.
ARINC 429: uni-directional, a unit either transmits or receives from a cable.

Number of units on a single bus

CAN: unlimited, although in practice no more than about 32 units will be sharing a bus to avoid data collisions.
ARINC 429: one transmitter can serve at most 20 receiving units on a single cable.

Since ARINC 429 has only a single transmitter, timely data arrival is guaranteed, while CAN has to incorporate transmission collision detection & correction which incurs non deterministic time overhead.

On the other hand, ARINC 429 only uses a parity bit for bit level error detection whilst CAN allows for various methods including CRC checks

Some of this data is obtained from an article on CAN bus in avionics magazine.

Newer ARINC busses like 629 or 664 (AFDX) allow for higher speeds and bi-directional communication. These may eventually replace ARINC 429 (but never underestimate how slow progress in aviation is)


What would the "wings level" button most likely do if activated in the event of a flat spin? If an aircraft equipped with a wings level button (such as the TBM 930) entered a flat spin, would pressing it accomplish anything productive?

I am aware that the purpose of the button is to return the aircraft to straight and level flight if the pilot becomes uncomfortable with the vehicle's orientation. However, what I am unsure of is whether this system can control both the engine and control surfaces in a manner that would be potentially helpful in a seemingly unrecoverable situation.

This video shows what happens in a spin.

The turn coordinator shows a left turn, and the slip indicator shows a skid (ball to the far left as well). To get out of it you'd want to push hard on the right rudder pedal.

The yaw damper doesn't allow full rudder deflection.

Also as the instructor shows, pushing the stick left and right does nothing.

The stall protection will push forward, again won't help.

The TBM 930 doesn't have an auto-throttle, so there is no engine control involved either.

The installed Electronic Stability and Protection (ESP) system doesn't handle developed spins—

Leveling at 4,500 feet, I performed a series of steep turns, slow flight, an imminent stall with gear and flaps down, and a power-on stall. As the stall approaches, the G3000’s Underspeed Protection (USP) feature, linked to the angle of attack computer, comes alive as it automatically commands the autopilot servos to lower the nose. ESP, meanwhile, will attempt to return the airplane to level flight if bank or pitch angle limits are exceeded.
— flyingmag.com

Summary:
The safety features on the TBM would alert and prevent getting into a stall or spin.


Is a night VFR rating a prerequisite for an EASA CPL? I'm wondering if I need to pay for a night VFR (NVFR) rating or can I just do my time building, ME, IR and exams to get a CPL? Is it possible without an NVFR rating?

According to FCL.610 (IR - Pre-requisites) you need to have a PPL or CPL and a night rating to apply for the IR.
If you do not have the IR, the night flying qualification (NFQ) is no requirement to start training for the CPL. According to the AMC appendix 3 of the Notice of proposed Amendment (NPA) No. 2008-17B night flying is part of a training course for the CPL.And FCL.315 states, that the applicant for a CPL shall complete a trining according to the appendix 3, cited above.

SO: If you have the IR, you should also have the NFQ but you do not need the NFQ to start training for the CPL.
However, you only need 5 hrs night flying to get the NFQ and there is no examination, i.e. the FI rates your skill.


What are the dimensions of the protected space provided by a holding pattern? What are the dimensions of the protected space provided by a holding pattern? Where and how does the FAA define this?

While this question may contain the answer, this question concisely asked something that is a valid aviation question and it warrants its own answer.

The exact answer to your question is found in a 500 page document titled "United States Standard for Terminal Instrument Procedures (TERPS)" that was revised and issued as Order 8260.3C on 03/14/2016. This is the answer to the part of your question about "where does the FAA define this."
As mentioned, the FAA uses templates. There used to be 31 templates of various sizes that are identified by pattern numbers 1 through 31. However, Patterns 1-3 are no longer in use. So there are now only 28 in use. Originally, these templates were literally plastic transparent templates. Now, most holding patterns are constructed using automation (i.e. computers). The following figure shows the exact proportions and geometry of every one of the 28 holding patterns in use today.

Point "L" (little orange circle) is the holding fix. This is a standard right hand holding pattern, (left hand holding patterns were drawn by flipping the plastic pattern over for a symmetrical left-handed pattern). The solid black line that runs from point "M" to point "L" is the holding course. All the straight line segments are defined by the definition of the respective Pattern Number as provided in the following chart.

Take a look at the dimensions of Pattern Number 4 on the chart above. Pattern 4 is the smallest holding pattern in use today. Specifically, see that the column M-E says 5.3 nautical Miles, and that column L-I/M-H reads 3.5 nautical Miles. Now look at the template in the figure above and find the line M-E. This is the protected distance from the holding course on the Holding Side of the pattern. Now, find the lines L-I and M-H. These represent the protected distance from the holding course on the Non-Holding side of the pattern. This is the answer to the part of your question about "what are the dimensions of the holding patterns and how does the FAA define it."
RANT:
Now my rant. I often hear pilots and even flight instructors talk about the "Protected Side" and the "Non-Protected Side" of the holding pattern. This is inaccurate. The FAA does not describe holding patterns in that way. There is either a Holding Side or a Non-Holding Side. BOTH sides are protected! Pattern #4, the smallest pattern in use in the USA, has 3.5 nautical miles of protection on the Non-Holding side. I plugged in all of the values in the chart above into Excel and calculated the ratio of Non-Holding Side protected area to Holding Side protected area, and all of the patterns had a protected area on the Non-Holding Side equal to approximately 2/3 or 67% of the Holding Side. That may not be as much protection as on the holding side, but it translates into multiple miles of protection.
Next time someone says Non-Protected Side of a holding pattern, take the time to explain to them that both sides are protected. Protection on the Non-Holding Side is necessary to protect aircraft entering a holding pattern using a parallel entry with a cross-wind that is pushing them away from the inbound course into the Non-Holding side during that initial 1 minute outbound entry.
End of RANT


How can I pay for flight school in the UK? I want to apply for the British Airways future pilot programme. However, it costs £125,000. The biggest loan I can get is £20,000 so where am I supposed to get the rest of that money?

I've heard people telling me that you can get a sponsorship, but I've looked online and cannot find any sponsorship deals because it's all self funded.

There are specialist firms providing loans for aviation training, however it is unlikely that you will be able to get a loan of the amount you would need for an integrated course without some form of security.

The security usually takes one of two forms.  The first is a charge on a property (belonging to you or your parents).  The other is an airline agreeing to act as a guarantor/sponsor, however this doesn't appear to apply in this case as this particular scheme states it is fully self-funded.

If you cannot raise the financing for this particular scheme, you can apply to other schemes that provide some sponsorship or underwrite the loan as they become available.  Naturally there tends to be more competition for these schemes.  Some are targeted towards under-represented potential pilots, such as the Amy Johnson initiative by Easyjet, where they will guarantee/underwrite the loan for a limited number of female trainees.

It is also possible to undertake modular training, where the cost can be closer to £50,000.  There are a number of organisations that can provide funding towards some of the costs, particularly for young pilots.  These include The Honourable Company of Air Pilots, The Air League and The Royal Aeroclub Trust.

Before spending significant sums on training, it is advisable to get a class one medical, to avoid possible disappointment after spending significant sums of money that cannot be recovered.


How many lives would be saved if the airlines turned all the seats around? The psychology and history of forward-facing seats has been answered well already here. I ask instead about how bad it is that seats are forward-facing.

For context, I was looking through Wikipedia's list of airline flights that required gliding, and a surprising fraction of the 30 incidents listed were fatal to some, but not all, of those aboard (47%). Averaged across the 30 incidents we get that 25.1% of those aboard died (noting that this average is pretty unscientific, and is subject to sampling and coverage biases; it's still interesting). Even among just incidents with fatalities on average less than half of those aboard died! I generated a scatter plot of the incidents:

This data surprised me a lot! My layman's intuition says that emergency landings should be a lot more bimodal, with basically all landings either being gorgeous US Airways 1549 style happy endings, or blazing fireballs with no survivors, with some very rare exceptions. Based on this intuition, I always figured it was reasonable that passenger seats face forwards; I thought "rear-facing seats wouldn't help that much anyway, edge-cases where it would have made the difference will be the rare exception to the rule".

But is this really true? It seems that maybe many deaths on commercial flights are incidents in this intermediate region, although I don't have the expertise to evaluate if rear-facing seats would help with how people typically die in commercial airline accidents.

Question: As a really rough ballpark, how much safer would commercial airline flights be (averaged across all commercial flights globally) if the seats were rear-facing?

The evidence is not the most recent one, but

  According to an article in the December 1952 edition of Naval Aviation News, “Passengers in Navy transport planes have ten-fold better chances of coming out of crashes alive, thanks to backward-facing seats which are being installed in all new planes […]". The unsigned article cites two Royal Air Force accidents involving a four-engine Hastings and a two-engine Valetta. Both had rear-facing seats that were credited with minimizing injuries to passengers.

Unfortunately, the link to the 1952 edition ends in a 404. Thanks to the detective work by Gerald Schneider we now have a working link. The article is on page 27. Another source cites a 1957 study, without a traceable source:

  An Air Force study in 1957 reviewed a series of crashes and concluded
  that injuries were seven times greater among passengers facing
  forward.

That a backward-facing seat is safer is indisputable, but quantitative data is very hard to find. Given the much higher wing loadings and landing speeds of modern airliners, possibly those ratios cannot be translated to modern aviation. While in the days of propeller-driven transports the difference between the forward- and backward-facing position might indeed have meant that the latter provided a significant advantage in survivability, the deceleration level in a modern airliner crash might make both equally unsurvivable. In addition, the data from mostly young, fit and healthy subjects involved in crashes of military transports might not translate easily to todays untrained, middle-aged and overweight passengers.

Circumstantial evidence cited in this 2016 study, however, indicates that even for modern airliners seating position is important. For an A340 runway overrun accident in Toronto in August 2005 it cites the Canadian TSB as saying:

  ‘One of the cabin crew, seated in the same general area as the crew
  and passengers who incurred serious impact injuries, was not injured.
  This cabin crew’s seat was aft-facing; the other seats were
  forward-facing.’

Another more recent paper gives more modest advantages: This 1996 study by the European Transport Safety Council lists them in a table and awards rearward-facing seats with only a 5% advantage overall or 19% if based only on impact fatalities:

Commenting on the table, the numbers are based on the 1995 Cherry study (CHERRY, R.G.W. and Associates Ltd (1995) Analysis of factors influencing the survivability of passengers in aircraft accidents Vol. I-III. EU DG VII contract) and

  These particular figures are not quoted in the study, but have been
  calculated from the data provided in the study report.


What are the Single European Sky (SES) and Functional Airspace Blocks (FABs)? Air Transport World is reporting that the European Commission has initiated legal proceedings against Germany, Belgium, France, the Netherlands and Luxembourg; for not implementing FABs by the deadline. A quote says:

  FABs are a cornerstone of the SES initiative and are intended to reduce the capacity, cost and environmental constraints that continue to dog Europe's fragmented air traffic management (ATM) system by establishing common airspace blocks arranged around traffic flows rather than state boundaries.

What exactly are SES and FABs, in laymans terms?

SES = Single European Sky Legal Framework. It started in 2004 when the EU Parliament and Council adopted Reg 549/2004 (framework regulation), 550/2004 , 551/2004 and 552/2004 (interoperability regulation). Also, a very important regulation was 219 which established EASA! (All these legislation is called SES I... amendments later came in place along a myriad of Implementing Regulations) which dealt mainly with What and How the Air Navigation Providers (ANSPs) must provide ANS services. This legislation aims at Uniting the National FIRs (Flight Information Regions) into BIGGER FIRs (Called FABs - Functional Airspace Blocks). Most of the operational advantages of FABs: Direct Routes, lower CO2 emissions and lower fuel burns for air companies are True and EU citizens will gain overall.

Since FABs will include the airspace of more sovereign nations, from a legal point of view, FABs need to be created with a Multilateral Agreement in the adjacent States.


What is the correct go-around procedure in a PA-44? I wanted some advice on a procedural-type question. In the PA-44 (Piper Seminole) go-around procedure, it is listed as follows:

  MIXTURES ............................................FULL RICH
  PROPELLERS ............................................ FULL INCREASE
  THROTTLES.............................................FULL OPEN
  Control Wheel...........................BACK PRESSURE TO OBTAIN POSITIVE CLIMB ATTITUDE
  FLAPS....................................................RETRACT SLOWLY
  GEAR.........................................................................UP
  COWL FLAPS........................................................... AS
  REQUIRED

(You can find this on any online version of the PA-44 PIM - here's an example on page 4-17.)

Now, the way I have always been taught is to go full throttle, carb heat off (not listed in PIM), flaps 40°->25° immediately, then 25°->10° at positive rate, and 10°->0° upon being above Vy, then gear up, and cowl flaps open.

I began researching the Airplane Flying Handbook and it states in the Transition to Multi-Engines section (page 12-18) that:

  With sufficient airspeed, the flaps should be retracted from full to
  an intermediate position and the landing gear retracted when there is
  a positive rate of climb and no chance of runway contact. The
  remaining flaps should then be retracted. [Figure 12-10]

My question is this: would a better go-around procedure be full throttle, carb heat off, bring the flaps to 25°, then gear up, then continue as previously specified? This would reduce the drag the gear is giving a lot sooner, briefly take advantage of the increased lift coefficient 25° degrees of flaps gives (that is the specified flap setting for the short field take-off), and also follow the AFH procedure.

Any procedure listed in the AFM for your airplane takes precedence, but a general go-around technique I use (and teach my own students) is as follows

1) Add power - on complex airplanes, verify mixture rich (or for best power at high altitude airports) and propeller controls are set for maximum RPM prior to pushing the throttles to full power.

2) Apply aft elevator pressure to arrest rate of descent and bring nose level with horizon.

3) With level flight attitude, set flaps from full to approach setting.

4) continue applying aft elevator pressure and establish climb attitude

5) Once climb attitude established and continuous positive rate of climb confirmed, retract the gear.

6) At sufficient airspeed and altitude to permit safely doing so, retract the flaps.

7) Set throttles and propeller controls for maximum continuous power and pitch for selected climb airspeed.  Trim aircraft to neutralize control pressures.


Why Boeing 737 main landing gear wells have no doors? My question is about the Boeing 737 main landing gears:

When the landing gears are up you can see a landing gear door to open in most planes and then it closes. But for Boeing 737 main landing gear are not behind well doors at any time of the flight.

Why are main landing gear wells opened during in flight?

To keep costs down. The extra friction from no gear doors is more than made up from the weight savings.


Are US pilots permitted to carry & use their firearm in countries where guns are illegal? On the question of Are pilots armed?, one thing this made me think is: for the few that are armed, are they allowed to bring their weapon into, for example, the UK?

What is the procedure? Does the gun stay in the cockpit or does it need to be checked by security once on the ground?

Presuming a pilot had to fire a gun over EU airspace, is he breaking the law?

Once you land you have to abide by the laws where you are. In the US federal laws (if there are any), when flying in US airspace.

Most US laws about airports and guns, only apply to the secured space. (Inside security), not the GA ramp or anyplace else.