What's are the advantages of having the pilot in the cockpit?

The concept would be a hard sell for both passengers and non-passengers alike. You not only risk lives in the air, but on the ground as well. I would not want a fully laden B747 flying above me. The biggest reasons are:

The human pilot in the cockpit has a vested interest in performing a safe flight. The vast majority of pilots are not suicidal (99.999%). The remote pilot on the ground does not have the same incentive.

Any computer system can be hacked. This would turn said B747 into a weapon.

A remote pilot does not significantly lessen the chances of human error. The remote pilots are still human. And, the programmers of the software needed to make remote piloting possible are equally human.

Satellite communication is not entirely fool-proof. It would have to be perfect to be considered safe enough to warrant that hazard. The current GPS interference is an example of that. That is one of the reasons why GPS is still considered non-precision for flight. You have to have the capability to use traditional NavAids even when you are using GPS.

When (not if) crap hits the fan (or fan disk), and there is a systems failure, the best chances to preserve life is to have the human pilot in direct control. Think of what happens in an electrically power failure, a systems shutdown, a loss of communications capabilities, etc.


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

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

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


Why don't airplanes have smoking cabins?

Just off the top of my head,

It would take up space that could be used for three or four paying passengers. This would result in increased ticket prices for everybody and the non-smoking majority have no incentive to subsidise a smoking cubicle.
It would require a ventilation system that would prevent smoky air from getting into the rest of the cabin, which would add weight and complexity.
It's a fire risk and a small fire from some idiot disposing of paper in the ashtray could spread; it would be hard to detect such a fire early because you couldn't just put a smoke detector in the smoking cubicle.  (I guess an infra-red detector would work.)
Almost nobody tries to smoke in the lavatory so reducing the occurrence of an event that hardly ever happens isn't worth much.
Rates of smoking are decreasing in most Western countries, so demand for such a cubicle is already falling.
Anti-smoking legislation is often aimed at worker protection: who's going to clean the smoking cubicle and what equipment will they need?
I doubt there's significant pressure, even from smokers, for such a service to be provided.


How do I use the takeoff and landing distance charts in the C172 POH?

There are many ways to calculate aircraft performance. Some ways are entirely manual through the use of formulas. Some ways use electronic means like apps and special calculators. Some ways use pre-calculated Tables. Then there are ways that use graphs and charts. Let’s tackle the charts way.

First, remember one thing. These charts are made from data obtained using highly experienced and skilled test pilots using brand new airplanes with ideal performance and under ideal conditions. Since you probably meet none of these parameters (most of us don’t), it is best to add as much as 50% fudge-factor to your results as a safety buffer.

Think of the Takeoff and the Landing Performance Charts as each being a combination of 4 separate charts.

The Pressure Altitude to Density Altitude conversion chart.
The effect of Density Altitude on weight chart.
The effect of wind on distance chart.
The additional distance needed to clear an obstacle chart.

To start your calculations, read any associated text on the chart. It will give you parameters that must be met in order to make the chart as accurate as possible. They may also give you factors to consider and/or adjust in your calculations.

The Pressure Altitude to Density Altitude conversion chart.

Next, find out the Pressure Altitude and Temperature at Field Elevation for your point of departure. You may have to obtain the Pressure Altitude by calculating it using your Field Elevation and Atmospheric Barometric Pressure reading. Another chart may be handy for this.

Start your graph entering at the horizontal Temperature axis at your Field Elevation Temperature. Follow the graph line vertically up to where it intercepts the line representing your Field Elevation Pressure Altitude. Follow the graph line horizontally to the right until it intercepts the Reference Line for the next section of the chart.

The effect of Density Altitude on weight chart.

Enter the next section at the point where your drawn graph line from the previous section intercepts the Reference Line. Draw a line that roughly parallels the diagonal lines immediately above and below your drawn line. Find the point at which your drawn line intercepts the vertical graph line representing the actual total weight of your aircraft at the point the performance data would be used (takeoff weight or landing weight). Draw another line horizontally from the point of interception, to the next Reference Line.

The effect of wind on distance chart

Enter the next section at the point where your drawn graph line from the previous section intercepts the Reference Line. Draw a line that roughly parallels the diagonal lines immediately above and below your drawn line. Find the point at which your drawn line intercepts the vertical graph line representing the actual Wind Component at the point the performance data would be used (takeoff or landing). Draw another line horizontally from the point of interception, to the next Reference Line. If the winds are calm, use the 0 wind graph line that coincides with the Reference Line. Your drawn line would then be an individual horizontal line from the reference line to the next Reference Line.

The additional distance needed to clear an obstacle chart.

Enter the next section at the point where your drawn graph line from the previous section intercepts the Reference Line. Draw a line that roughly parallels the diagonal lines immediately above and below your drawn line. Find the point at which your drawn line intercepts the vertical graph line representing the actual obstacle height AGL you would have to navigate/avoid at the point the performance data would be used (takeoff or landing). Draw another line horizontally from the point of interception, to the vertical axis on the right. If there is not an obstacle, use the 0 height graph line that coincides with the Reference Line. Your drawn line would then be an individual horizontal line from the reference line to the vertical axis.

Results.

The value you read on the y-axis of the chart is the minimum distance you need to accomplish the stated phase of flight under the given conditions. As a reminder, there will be different charts for different phases of flight. A phase of flight may have multiple charts. An example of this is a chart with flaps and a chart without flaps. Make sure you are using the correct charts and conditions for your aircraft and situation.


What is the icing probability required for an AIRMET?

For any AIRMET, the event must have a probability of 50% at least (that is more than playing playing heads or tails).

Related US NOAA definition for AIRMET Z:

  AIRMETs are issued every 6 hours, where there is a 50% probability
  that any of the following en-route weather phenomena will cover an
  area of 3000 square miles or greater.

Phenomena for AIRMET Z are:

  Icing: Areas of moderate airframe icing, other than convectively
  induced, including the areal extent. Freezing Level information is included after AIRMETs for moderate icing or statements indicating that no significant icing is expected.

Freezing level is defined as:

  The lowest freezing level above the ground or at the SFC as
  appropriate. Freezing levels are delineated using high altitude VOR
  locations describing the location of the lowest freezing level above
  the ground or SFC as appropriate.

  Freezing levels above the ground are delineated at 4000 feet intervals
  above mean sea level (AMSL). Multiple freezing levels above the ground
  are delineated using "BOUNDED BY" followed by high altitude VOR
  locations. The range of freezing levels across the forecast area is
  also included.

G-AIRMETs, the graphical version, are issued every 3 hours (but still describe the next 6 hours).


Is it allowed to mount fake missiles on a civilian aircraft?

Importing former military aircraft

  Former military aircraft imported from ANY other country require an import permit issued by the Department of Treasury, Bureau of Alcohol, Tobacco, and Firearms (ATF). This is granted by ATF using an ATF Form 6, Application and Permit for Importation of Firearms, Ammunition and Implements of War. Additionally, these former military aircraft are required to be demilitarized in order to clear U.S. Customs (FAA).

Getting a certification

  Unless the aircraft are used for an approved civil research and development (R&D) project, former military aircraft owners/operators must permanently demilitarize their aircraft before FAA certification (FAA).

So those aircraft are permanently demilitarized and cannot release ordnance or fire bullets. Since there are multiple examples, it is legal (in the US at least), and with the demilitarization there is no worry such aircraft would be able to release live ordnance if the owner somehow was able to obtain some.

Inert missile

I wasn't able to find text regarding mounting fake missiles, but a line from Dr. Strangelove came in handy:

  Air Force Base Guard
  You sure gotta hand it to those Commies -- Gee, those trucks sure look like the real thing, don't they? -- I wonder where they got 'em from? -- Probably bought them from the Army as war surplus...

I found inert ordnance for purchase, like the one above. And the blue line on the missile on the L-39 indicates it "does not contain a live rocket motor".

Livery

In AC 45-2E I did not find anything about using USAF or foreign military markings, but most probably that falls under freedom of speech in the US.

Related: Why can civilians not fly demilitarized US fighter jets?


How are landing aircraft handled during an emergency runway closure?

As a tower controller, in case of an unexpected unusual situation for an aircraft on final approach, this will be my list of priorities:

Clear the runway of other traffic
Determine if fire and rescue services need to get involved
(Call fire and rescue services)
Call approach and ask them to stop inbound traffic. In case of other traffic on final behind the emergency, coordinate missed approaches
Instruct other aircraft on final to go around, in accordance with the coordination with approach

The above points will take me no more than 30 seconds to get through. This takes care of the most immediate priorities. I will then await the landing of the emergency plane, and coordinate with fire and rescue as appropriate.

As for departing traffic on the ground - aircraft on their gate will be instructed to stay there. Aircraft taxiing to the runway will either continue to the runway holding point or be turned around to a gate, if available - this depends on whether I expect the runway to be closed for a long time (say, more than 20 minutes). The same, more or less, applies to VFR traffic in the control zone intending to land. They can hold in the air if I expect to reopen the runway shortly, otherwise they might have to find an alternate; I will coordinate any diversions with approach.

Once I have a hold of my own traffic, I will call the operational supervisor and inform them of the situation. They will take care of stopping additional inbound traffic if required, and coordinating with adjacent units and sectors. I might also call approach again directly to let them know how the situation is developing.

It will be up to approach, in cooperation with the supervisor and based on the information I provide, to determine if aircraft on initial approach should be diverted, or if they can hold in the air awaiting a runway reopening. Each individual aircraft will require individual handling, to determine if, where and how they want to divert.

Once the runway is reopened (after fire and rescue have finished their work, the emergency airplane has been removed, runway inspection carried out and so on), I will coordinate with approach and the supervisor to start inbound traffic again (possibly with a reduced rate), and start getting my own departures rolling again.

As you can see, there are a lot of "if's" in the above. A lot of decisions have to be made, and the basis for making said decisions changes depending on the situation. There is no set checklist or rulebook for when something like this happens, because the required actions will vary. But that is what we get paid for after all - as an air traffic controller you have to be creative and flexible, especially when unusual situations occur.


Does normal laws apply when the aircraft nose is vertically down?

Yes, always. Physics doesn't care much about the aircraft's attitude and cannot be switched into different modes.

While the nose points straight down, a stall is hard to achieve since no lift is needed - the weight is balanced by drag and inertia. However, when you pull abruptly and start to pitch up, the aircraft can stall while the overall attitude is still partially nose-down. If the pitch inertia is small, the rotation about the lateral axis will increase the angle of attack quickly while the flight path is still more or less straight down. At this attitude the stall angle of attack can be exceeded and the aircraft will stall. This is not unusual - pilots are routinely warned not to pull too hard after ending a spin. And yes, entering the next spin is entirely possible. This is especially likely when the sideslip angle has not been set to zero after ending the first spin. In most cases, this second, unintended, spin is in the opposite direction from the first spin because the pilot maintained his anti-spin rudder deflection for too long.

There have even been cases of supersonic spins.

A few details will help, though. A high pitch rate will delay the stall to an angle of attack up to 50% higher than the stall angle at zero pitch rate. Flying faster will increase the Reynolds number, so stall is slightly delayed when compared to the stall conditions at 1g. Both effects, however, will increase the wing root bending moment, and pulling out of a dive will run a real risk of breaking off the wings when you pull too hard.


Is a magnetic compass required for an IFR flight?

A magnetic heading indicator is required, but not necessarily a wet compass, like this one:

Image Source: Wikipedia - Author: Chopper

Digital devices or combined devices are also possible:

Image Source: WikiPedia - Author: Mysid

The required equipment for VFR flights states, as already posted in this question:

  §91.205   Powered civil aircraft with standard category U.S. airworthiness certificates: Instrument and equipment requirements.

  (a) General. Except as provided in paragraphs (c)(3) and (e) of this section, no person may operate a powered civil aircraft with a standard category U.S. airworthiness certificate in any operation described in paragraphs (b) through (f) of this section unless that aircraft contains the instruments and equipment specified in those paragraphs (or FAA-approved equivalents) for that type of operation, and those instruments and items of equipment are in operable condition.

  (b) Visual-flight rules (day). For VFR flight during the day, the following instruments and equipment are required:

  ...

  (3) Magnetic direction indicator.

  ...

The text further states for IFR:

  (d) Instrument flight rules. For IFR flight, the following instruments and equipment are required:

  (1) Instruments and equipment specified in paragraph (b) of this section, and, for night flight, instruments and equipment specified in paragraph (c) of this section.

  ...


Would a drone strike be more dangerous than a bird strike?

There is a numerical study on the topic at VirginiaTech, where they simulated a 5kg drone being ingested by a turbofan, some pictures related to the study below:

On the same  Aerospace America Article it can be read that:

FAA will begin testing of drone ingestion next year
The metric for danger is the density of the material, so metallic parts are more critical than the bird bones/tissues. Modern drones have more aluminum parts, but the most critical component of a Drone ingestion would be the batteries.

Comparing different sizes, a commercial quad copter is around 1.4kg, while the most frequent bird impact (from FAA database) is around 1.8kg.

This is not the worst case scenario since larger drones are commercially available, and a goose, which can weight up to 6kg.


Would an accurate weight of a loaded aircraft be helpful?

A friend of mine was FO on a regional jet with 50 passengers. During the take-off, the PIC could not rotate the plane at the calculated VR, but only much later. They reported the incident during the flight. The luggage containers were re-weighted at the destination, and it turned out that one of the containers had a grossly wrong weight recorded at the origin.

Weighing mistakes can end in a disaster, especially for smaller jets. Systematic weighing of ready to launch planes would eliminate this risk. I am not aware of an accident caused by this kind of weighing mistake, but surely there have been accidents due to overloading or wrong load distribution.

The technology to build load sensors into the undercarriage is available and it appears that a few planes are equipped with it.

On the other hand side there must always be a risk assessment with a trade-off between costs, likelihood and severity.


How does vorticity change the lift coefficient of an airfoil?

Shed vortices from unsteady flow over an airfoil result in decrease and phase lag in lift.

Ref: https://www.researchgate.net/figure/Vortex-shedding-from-an-airfoil-oscillating-in-pure-heave-2_fig2_251006855
Using thin airfoil theory in incompressible flow, the lift coefficient for an airfoil undergoing cyclical pitching and/or heaving can be expressed as (Ref. Drela, Flight Vehicle Aerodynamics):
$$C_l=\text{Re}\{ C(k)C_{l_Q} + C_{l_A} \} + C_{l_0}$$
$C_{l_Q}$ is the circulatory part of the lift, which, at steady-state, is equal to $2\pi\alpha$. $C_{l_A}$ is the non-circulatory part that have to do with fluid inertia; at steady-state, its contribution would be zero. The last term is the camber contribution. $C(k)$ is the Theodorsen function, which serves as a complex gain on the circulatory part of the lift. $\text{Re}$ here refers to the real-part of the function, not Reynolds number.
The decrease in lift and lag is readily seen in the Theodorsen function, where $C(k)=F(k)+iG(k)$:

Ref: https://pdfs.semanticscholar.org/8457/c72b980f2f129a9f211617a5cdee4e162b75.pdf
The reduced frequency, $k=\frac{\omega c}{2V_\infty}$, denotes how many airfoil chord lengths per flow distance traveled in one motion period ($\omega$ is the angular frequency of the cyclic motion), and is a measure of how much the cyclical motion affects the flow on the airfoil. As $k \to 0$, there is no attenuation in lift and no phase lag; this is the quasi-steady aerodynamics. As $k$ increases, there is increasing attenuation in lift, up to 50%. The maximum phase lag occurs at $k \approx 0.25$.
For most rigid-body motions in commercial aircraft, the reduced frequency is low and the quasi-steady assumption is valid.


In the US, is it legal to cover up some of the required gyro instruments during flight under IFR in actual IMC?

To my knowledge there's nothing illegal about practicing partial panel in real IMC, however it's a spectacularly bad idea to do so. A failure of vacuum instruments in IMC is an emergency because you can easily lose orientation and dig a big hole in the ground. A safety pilot won't be able to help unless they have a separate set of instruments to rely on, and even then upset recovery in IMC is inherently less safe.

If you want to practice partial panel pleeeeease do so in VMC, with a safety pilot.


How accurate are these Stall Diagrams depictions of relative wind?

The diagrams are accurate.¹

The thrust, produced by the engine, is one of the forces acting on the airframe. The others are lift, drag and weight (a.k.a. gravity).

(from How It Flies, chapter 4)

When these forces are in equilibrium, i.e. their (vector) sum is zero, the aircraft flies straight, in whatever direction it does (that is what Newton's first law says: an object remains at rest or continues to move at constant velocity unless acted upon by external force).

When the forces are not in equilibrium, the aircraft accelerates in the direction of their sum (that is what Newton's second law says: the sum of external forces on an object is equal its mass times its acceleration). But direction of acceleration and direction of velocity are independent. If the aircraft is turning, acceleration is to the side while velocity is (approximately) forward. If it is slowing down, acceleration is aft and velocity is still forward.

So thrust and direction of flight don't have to be parallel.

For a more practical argument, imagine an airplane doing the tailslide aerobatic manoeuvre. The nose points up and the engine is running and producing thrust up. But because the thrust is less then the gravity, the aircraft slows down until it stops midair and starts to fall back to the ground, tail first. So for a moment, the relative wind will come from aft while the engine is still producing forward thrust. Only then will the aircraft pitch over to restore normal airflow over the wings and return to fully controlled flight.

Now of course since the lift and drag forces depend on the relative wind. The lift, which is the aerodynamic force perpendicular to the relative wind, increases with angle of attack, which is the angle between the relative wind and the wing planform, until stall angle of attack is reached.

So when the plane is flying level slowly, the nose is pointed up to create sufficient angle of attack. The thrust is thus pointing slightly up, so small part of it balances a bit of weight, reducing the lift requirement. That is why aircraft actually stall at slightly slower speed when the engine is developing full power than when it is stopped.

Read the How It Flies chapter 4 for more details on the forces. And the rest of How It Flies; it explains the physics pretty well.

¹ That is accurate regarding the direction of oncoming relative wind. They are not accurate regarding the flow around and behind the wings.


What would be a simple aerodynamics simulation software for a student?

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

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

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

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

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


At the time of the imagery, it appears the airport was undergoing major renovation, now completed at least insofar as the runway is concerned. See iqaluit-airport-s-runway-gets-a-facelift-as-construction-completed. During the reconstruction they kept a minimal portion of the runway open for operations, enough to bring 757s in but not enough to get 767s in.

If you look at the image, note all the construction activity and also the parked aircraft. Note that the Xs are on the right side of rwy 34, and leaving the left half of the runway open. Farther down the rwy the Xs are in the middle, so I believe the image was taken while they were reconstructing the rwy while leaving enough of it usable for operations.


Why is the ISOLATION VAVLE switched to OPEN during ENGINE START on Boeing 737?

Position OPEN is guarantee correct work supply air bleed, AUTO is not. For safety.


What liability concerns would drive an airplane homebuilder to scrap their plane?

I understand that the aircraft owner had sought for some time to donate the aircraft. I would presume that he had come to a time in life where he was, or felt he was, no longer able to fly the aircraft, and so was seeking to rid himself of what may have become a burden (hangar fees, etc.).
To quote liberally from the builder/destroyer's daughter who created and uploaded the YouTube video (this is quoted from what she wrote in the video description):

It took him two years to make this decision about his plane. He did actually try to donate it to a couple of aviation schools in the area and the schools politely refused the offer. He also tried to donate to a local museum and was also refused.
He knew when he built the plane he might face this decision one day, but he hoped some of the laws would have changed by that time.
[...]
Mr. Ron Rapp, author of the article “A Tragic Pile of Twisted Metal” and noted blogger on his website The House of Rapp., highlights many reasons my Dad made this decision among others.
A couple months before my dad made his final decision, a local fellow pilot was named in a lawsuit because he sold the plane he built to a man that later crashed and killed himself in the plane. The spouse of the buyer filed the suit and also named other companies who made parts used to build the plane.
Many have commented that he should have used a limited liability entity, such as a LLC or a corporation to sell the plane. However, because the plane was not, at the time of manufacturing, owned in a properly capitalized limited liability entity with a legitimate business purpose and was, in fact, used purely for personal reason, courts would in almost all cases “pierce the corporate veil.” Therefore, this does not offer adequate (or any) protection.

I don't think I can add a whole lot to that. Apparently, he had decided that he was unwilling to take on the liability of letting someone else fly what he had built. In the absence of a party interested in the aircraft for anything other than flight, he chose to destroy it.


What does svc tar/ssr u/s mean?

Terminal area surveillance radar and secondary surveillance radar (raw radar return and the secondary return from your transponder) is unserviceable.

If you were VFR you could practice the approaches without ATC radar vectoring, or ATC could give you a non-radar routing via an airway, then transition route, then the instrument approach procedure.

In other words, the area for the time being (NOTAM period) has no radar.  Non-radar procedures would be utilized.  If the local ATC area was normally a radar environment and the radar equipment was taken down for preventive maintenance (for example), providing separation for practice approaches may be more than they are willing to do.

In the US ATC system, controllers are initially trained, tested, and qualified using a non-radar environment at the FAA Academy. Non-radar approach control is infrequently necessary in actual operation (unless it is in an area where radar coverage is not available full time, which is becoming rare in the US).

Call the local ATC Approach Control in the area you are referring to and see what services they can provide.


Where do Russian and Chinese airliner manufacturers test their airliners?

Almost all Russian (Soviet) aircrafts were tested in the Zhukovsky Airfield (Ramenskoye Airport) near Moscow.

The Comac is building a Flight Test center at Dongying, Shandong province near the Dongying Shengli Airport. The flight test of aircrafts are expected to be carried out from here.

As Peter noted, Antonov test their aircrafts at Kiev Airport, including An 225, the largest aircraft in world.


What are a few main differences between ATC interactions for rotorcraft vs fixed-wing?

A helicopter can be cleared to depart from any position on an airfield, however there are a lot of considerations that would go into that.

There is no regulation in the US, and I'm almost certain there isn't an ICAO SARP that states a rotary winged aircraft must depart from a designated position on the airfield. Based on local conditions, volume & types of air traffic, and how familiar controllers are with handling a helicopter, there may be some localized procedures, but nothing regulatory.

As far as hovering, there are no prohibitions aside from local airfield procedures. If given a hold during an IFR flight, the rotary wing pilot will fly it in the same fashion as a fixed wing aircraft. To hover in a specific spot for an extended period of time at altitude of not practical due to lack of visual cues needed to hover. Some have a system of Auto-Hover, but that's generally used for extended hovering close to the ground.

Even if it were desired, in many cases it wouldn't be possible. Hovering requires a significantly higher amount of power when done so outside-of-ground-effect (OGE), which is a key metric you need to understand prior to every flight based on that day's conditions and how heavy you are. The extra power required burdens more gas, and in many cases requires a good percentage of the pilots available attention.

If burning the extra gas isn't enough, most civilian rotary-wing aircraft are not equipped with the power needed. Even those military helicopters with two engines (think UH-60 Blackhawk) are limited at higher attitudes.

I think that was all the questions.


How has weight been reduced in commercial aircraft design and how will this trend continue?

Perhaps the biggest weight reduction in aircraft across the board has been the use of composite materials over aluminum. This extends from small GA aircraft all the way up through airliners like Boeing Dreamliner. In the retro fit game, some older planes have been certified to take newer composite propellers. Even small savings matter according to this article

  LED modules give on average a 40% weight saving over the incandescent
  modules they are replacing, which improves fuel economy

Glass cockpits and modern computerized avionics tend to weigh less and offer more than their earlier steam gauge counter parts. Even in the space shuttle.

  The system also provides greater backup capability, weighs less and
  uses less power than the original design.

Another thing that has made a fair dent in take off weight is how fuel efficient engines have gotten. While there is a practical limit to this as engines have gotten more efficient the need to carry fuel has dropped or planes can go farther on the same fuel. In a similar vein as weather planning/predicting has gotten better fuel loads (while still in compliance with FAA reserve regulations) may be slightly lighter as they can now be more precisely calculated.

The one thing that has gotten heaver is the passengers...


Is having the tailplane at the wings backwash a design flaw?

I would say not really. The main impact would be on what incidence angle to set for the horizontal stabilizer because of the difference in local flow angle in or out of the downwash, and on the trim changes to expect if there are wing flaps, larger trim changes in the downwash, less if out.

For your ultralight, I would say the priority is simplicity and lightness, so just stick the horizontal tail at the most structurally convenient location, which is more or less where it is in the picture, like 90% of the other airplanes out there.

Size it based on the standard formula, make an educated guess (er... calculation) on the incidence angle to set, but make an attachment for the stab leading edge with multiple holes that allows you to change the incidence after flight testing.

And remember that when you test fly your ultralight you are effectively an Experimental Test Pilot taking the risks that go with that job description.


Why are airlines so concerned with checked baggage weight?

Airlines do care about your carry-on weight and even your weight. Many have carry-on weight limits, which low-cost carriers usually enforce, weighing the carry-on and tagging it as cabin luggage. Full-service airlines rarely bother.

One reason they don't measure your weight is that most people wouldn't feel comfortable getting weighed in front of strangers, then charged for that. Only Air Samoa currently weighs each passenger and tickets them by weight. In the West, weight is a contentious issue, so an assumed average is used for passengers. Such assumptions have crashed small planes, and in special circumstances like sports charters, actual weight is used. Finnair weighed volunteering passengers to get a better sample.

Weight costs money to carry, and not just in fuel burn. Luggage shares its volume with cargo, which airliners from the A320 up are designed to carry in the hold. Lately, cargo tends to get become more profitable than passenger service. Electronics and other high-value items cost more in depreciation and time value to ship by sea and land than by air, creating massive demand for air freight.

The A320 is 42.6 tons empty, but that's not the number that matters. The number that matters is its 78 tons MTOW, and how short of that it comes after adding pax, luggage and fuel to the 42-ton OEW. That spare weight is money in standby cargo.

Giving potential 175 passengers an extra 20 kg each (long-haul FSA vs average LCC allowance) could, if everyone used it all, add up to 3.5 tons total. Freight rates vary widely, but on a 3,000 mile flight that's worth \$7k-\$10k in freight revenue, or \$40-\$60/pax. Admittedly that's on the upper end of the range, but you can see there's money to be made. For an A320 that only costs ~$7k/hr to fly, it's a lot.

Less ethically, moving weight and volume from luggage to carry-on is profitable for a mixed passenger/cargo airline. Checked-in luggage has to be weighed in all cases, to ensure each piece is within safe limits for manual handling. This known weight then eats into the takeoff weight calculation, leaving less for cargo.

As airliners are designed to take off with one failed engine and carry reserve fuel for failures and diversions, this extra power works as weight safety margin when nothing fails. In practice weight margins rarely get pushed - most flights are volume-limited, with enough weight margin to take off at reduced power. Still, less luggage means more cargo means money.


Why does the FAA mandate a temperature indicator for all manned balloons?

A hot air balloon (including the air in the envelope) has tremendous mass, so it takes a long time for a change in buoyancy to cause a change in vertical speed.  Watching for temperature changes on the Envelope Temperature Indicator will help a pilot anticipate changes in the balloon's vertical speed before they have actually had time to occur.

From page 7-4 of the FAA's Balloon Flying Handbook:

  "Ascents and Descents

  The temperature of the air inside the envelope controls balloon
  altitude. A balloon that is neither ascending nor descending is in
  equilibrium. To cause the balloon to ascend, increase the temperature
  of the air inside the envelope. If the temperature is increased just a
  little, the balloon seeks an altitude only a little higher and/or
  climb at a very slow rate. If the temperature is increased
  significantly, the balloon seeks a much higher altitude and/or climbs
  faster. If the balloon is allowed to cool or hot air is vented, the
  balloon descends.

  Even without the input action by the pilot, it must be remembered that
  the air inside the envelope is dynamic. The air mass is constantly
  moving within the confines of the envelope, attempting to seek a level
  of equalization. While it varies with each envelope, input action by
  the balloon pilot can take from 6 to 15 seconds to be realized as a
  reaction by the balloon. Planning the maneuver, anticipating the
  reaction time, inputting the proper burn, and observing the reaction
  must result in smooth and natural movement by the pilot."

Also, as another related answer has noted, under some conditions it is possible for a pilot to bring the envelope to an unsafe temperature by excessive operation of the burner.  Monitoring the Envelope Temperature Indicator allows this to be avoided.  For a given desired maximum envelope temperature, the outside air temperature determines the total gross lift that is available at any given density altitude, or the density altitude that can be reached with a given gross weight.  See the FAA's Balloon Flying Handbook for more.


There's a line of airplanes that have already done it, at least a bit.
The Rutan tandem wing Quickie designs are exactly that configuration, except that the wings are radically staggered because the forward one is the trimming/pitch control surface, and the dihedral/anhedral angles are shallower.  But looked at from straight ahead, there it is.

The anhedral of the front wing is mostly there because that's where the wheels go. Versions of the 2 seat Q2 that have a conventional tricycle gear, have a nearly straight lower wing because the most of the anhedral is "in the way" (tips near the ground become a problem now without wheels there).
The problem with the configuration is other than being able to put the gear at the wing tips in Rutan's application, there's no point to it.  That anhedral wings cancel out the dihedral wings, form a roll stability perspective, making the result more or less the same as making all the wings straight.  If you do want to put the wheels there, you have to make the spars do double duty as really long leaf springs (bending loads from landing are much harder on the spars than flight loads), and there are ground handling issues with the wheels so far apart.
So might as well avoid the hassles of fabricating bent spar beams and make them straight across in the first place, or at least with more normal dihedral angles. It's more or less just something that looked cool from a science fiction perspective.


Is ear protection necessary for General Aviation aircraft?

This study on cabin noise with experiments in a Cessna 172s and a Piper PA-44 got the following results (noise comparisons are mine):

Peak:

Without headset: 101.3 dBA = rock concert (not front row though)
With headset: ~88 dBA* = vacuum cleaner (old bag-style ones, not Dyson...)

Average:

Without headset: 86.26 dBA = heavy traffic (by the side of the road)
With headset: ~73 dBA* = cloth dryer

Those value are not terrible per-se but on the long term ear damage is very likely.

*The study found that a headset reduces the loudness by 13 dBA in average. The reduction should be even higher with a noise cancelling headset.


In this F-104 V-n diagram, why does the stall speed (in terms of IAS) decrease with altitude in some parts of the flight envelope?

As an airplane approaches Mach 1, all pressure changes grow with the Prandtl-Glauert factor of $\frac{1}{\sqrt{1-Ma^2}}$. Therefore, the lift curve slope increases so the wing produces more lift at the same angle of attack and dynamic pressure the closer its Mach number is to 1. On wings with thicker airfoils and higher aspect ratio the maximum lift coefficient drops in the transsonic region; however, thin wings of low aspect ratios are unaffected by this.
NACA TN 3469 by Edward Polhamus compares wings with varying sweep angle, thickness and aspect ratio. The plot below shows that the Prandtl-Glauert effect is strongest for unswept wings and the transsonic lift bucket disappears for thin wings with an aspect ratio of 4 and lower. The F-104 had a 3.36% airfoil and an aspect ratio of 2.45.

This effect also shows up in the maximum lift; the plot below is from Sighard Hoerner's Fluid Dynamic Lift, chapter 4. It shows how the Mach number affects maximum lift: Small leading edge radii show a loss of maximum lift at moderate Mach numbers but perform well at transsonic speeds.

The indicated stall speed decreases with altitude because the lower temperature lowers the local speed of sound and brings the airplane closer to Mach 1 and thus to higher maximum lift. This effect is limited to subsonic speed close to Mach 1 which explains why those corners only show up when the indicated airspeed correlates with Mach close to 1 at that particular altitude.


Does anyone know of sources for ATA 206?

Airlines for America (formerly known as Air Transport Association of America (ATA)) maintains a website for their publications and subscriptions. You can access all/several of their specification documents.

Spec 100 (Manufacturers' Technical Data) can be downloaded from this page, by just paying an exorbitant a minimal fee of $650.

I am not sure which spec contains Chapter 206.


How does the FAA compute the values in TPP's Climb/Descent Table?

Given a required climb or descent in feet per minute and ground speed in knots, compute the target VSI reading with required climb/descent multiplied by ground speed divided by sixty, or

$$\delta_{VSI} = \frac{\mathrm{RCD} \times \mathrm{GS}}{60}$$

Apply dimensional analysis to see why this works. Informally, we can think of nautical miles and hours in the numerator and denominator as canceling each other out to leave a figure in feet per minute.

$$
\delta_{VSI}\ \frac{\mathrm{ft}}{\mathrm{min}}
=
\mathrm{RCD}\ \frac{\mathrm{ft}}{\mathrm{nm}}
\times
\mathrm{GS}\ \frac{\mathrm{nm}}{\mathrm{hour}}
\times
\frac{\mathrm{1\ hour}}{\mathrm{60\ min}}
$$

Fundamentally, trigonometry determines the values given angles in the leftmost column and the FAA’s definition of a nautical mile being 6,076.1 feet. In a right triangle, tangent is the ratio of the opposite leg to the adjacent leg for a given angle $\theta$, illustrated below for a climb.

For the values in the table

the adjacent leg is exactly 1 nautical mile
the angle $\theta$ is the precise value from the leftmost column
the opposite leg is unknown and is the desired ft/NM value

The core formula is $6,076.1 \tan\theta$ for the ft/NM values, and this is the derivation of the values in the Vertical Path Angle box outlined with a heavy border. Outside this box, the climb rates are rounded to the nearest multiple of 5. The rest of the table values use the $\delta_{VSI}$ formula above.

For reference, see a Google spreadsheet that computes climb/descent rates using the above. The formula for altitude change for a climb or descent at 2.0° over 1 NM is of the form

=mround($O$1*tan(radians(B4)),5)

The value in O1 is the number of feet in one nautical mile. The trigonometric functions in Excel and Google Sheets deal in radians rather than degrees, where a complete circle has $2\pi$ radians.

The formula for the $\delta_{VSI}$ values in feet-per-minute is either

=mround(D$3*$C4/60,5)

or

=D$3*$C6/60

depending on whether the cell is inside the Vertical Path Angle box, i.e., whether the value should be rounded to the nearest multiple of 5 or not.

There are discrepancies, no more than 15 feet per minute. Some of the FAA figures are more conservative, some less. I was not able to discern a pattern; for details, see the color coding in the Computed sheet or the Deltas sheet in the linked workbook. The odd duck is for a 2.0° climb at 210-knot ground speed: the FAA table gives an unrounded value of 743 feet per minute rather than rounding as with its neighbors.

Stack Exchange does not support tables in their Markdown flavor, so a screenshot of the computed table is below.


In countries outside of the US, 7777 may be used by test transponders (RABMs) to check correctness of radar stations (BITE). e.g. on top of a mountain.

In the US, it seems that it is used as well on active air defense missions without ATC clearance. This would mean that the interceptor aircraft would change it's squawk to 7777 for the military/civilian air traffic controller to see it properly (if not filtered out on civil radars).

A link to the US intercept procedures is here.


What is the name for yaw, pitch and roll together?

Roll, pitch and yaw are referred to in one word as the attitude.


Why does the U-2 Dragon Lady not have swept wings?

Sweeping a wing costs weight, for several reasons. Therefore, if the goal is to fly high and achieve long range, an unswept wing is the better choice. Only when transport performance needs to be maximized will a moderately swept wing look better.

Why is a swept wing heavier?

Sweep reduces aerodynamic efficiency, so a larger wing is needed to create the same amount of lift.
Sweep introduces torsion when a straight wing will mostly see bending only. Adding torsion strength needs more structure.
The stall characteristics of a swept, high aspect ratio wing are extremely unpleasant and require a healthy margin from the stall angle of attack, when flying high requires to fly just at the edge of stall.

In the end, Kelly Johnson decided to cut weight and drag as much as possible but not to pursue maximum speed to achieve the greatest flight altitude. Another reason was that the U-2 begun as a modification of the XF-104 with extremely stretched wings. Adding sweep would had resulted in too many modifications to the U-2 fuselage, which was initially built in the same tooling than that of the XF-104.


What are the FAI rules for circumnavigating the world?

"mins" linked to a set of rules at https://www.fai.org/sites/default/files/documents/sc_section_2_2013.pdf , I will try to interpret these in light of your question. I do not take any position on whether those are the official rules and I do not gaurantee my interpretation is correct. I have not read the entire document, just the parts that seemed relavent after searching.

There does not seem to be an official record for youngest flight around thw world. There are records for the fastest round the world (eastbound and westbound) and a circumnavigator diploma (not a record) for flying around the world.

Neither of them seem to have a restriction on the length of invidiual flight legs. Surprisingly other than the polar circumnavigations there doesn't seem to be any requirement to cross the equator.

The author of the route you posted gives a distance of 21738 NM which translates to 40258 km . The speed around the world (eastbound and westbound) records have a minimum distance of 36,770 km, there does not seem to be a maximum number of control points for this record.

The requirements for the circumnavigator diploma are a bit different, there are a maximum of 20 control points which may reduce the measured distance, but the distance requirement is much lower for the circumnavigator diploma.

So this route seems to pass the critera for both the fastest round the world record and the circumnavigator deploma.


Why does the stick force per-g test require it to be harder for pilots to pull back on the yoke instead of easier?

No because if stick force per G is too low, when maneuvering it becomes too easy to pull a lot of G and that's bad. It's like having power brakes in your car that don't build up more resistance in the pedal the harder you brake; it becomes difficult to regulate braking effort and too easy to lock the brakes (assuming no ABS).   Like with brakes, it's desirable to have the stick force build smoothly  with G force, because this provides good tactile feed back that helps you regulate how hard to pull.

If the force gradient is too shallow, too little effort is required to pull G and if above maneuvering speed it becomes too easy to pull the wings off by yanking on the stick too hard, and if below maneuvering speed, too easy to enter an accelerated stall while maneuvering.

It's an interesting point you brought up because there is a very popular 2-place cabin homebuilt airplane called the Wittman Tailwind, that's been around since the 50s. A very speedy, efficient airplane, designed by a famous air racer.  It has a very shallow stick force gradient, which builds to only about 5 lbs at limit load (I'm recalling from an article from the 80s).  This means if you are above maneuvering speed, it only takes a 6 or 7 pound pull on the stick to possibly pull the wings off, or at minimum bend something.  Wittman designed in the shallow force gradient on purpose because he was a pylon racer and really liked very light controls including pitch, more or less for similar reasons as you described.

However the Tailwind is not for the ham-fisted.  A pilot that is used to the airplane and had a light touch would be fine with it and would enjoy the very low stick forces, but for someone not adapted to it, it's dangerous.  Most airplanes have stick forces that build to 20-40 pounds or more, but you are never pulling that force in anything but aerobatic maneuvers.  Most normal maneuvering requires a 5 or 10 pound pull, and you're only holding it for a short time.

Transport airplanes with hydraulic controls get their stick force gradients by artificial feel devices that mimic the feedback forces that you would feel from airloads if the controls were manual, with loads that increase with speed and G.  I dimly recall that on the CRJ airliners the feel force for pitch was limited to 50 lbs and I believe most transport airplanes are similar.


Why do sailplanes have such large tails?

Keep in mind that not all sailplanes are designed for extremely light weight.  Decreasing the weight also decreases the minimum sink rate, but doesn't help the still-air glide ratio, and actually hurts the glide ratio against a headwind.
Even in sailplanes that are designed for very light weight, designers have sometimes thought it worthwhile to employ a rather large vertical fin.  A good example of this is the Carbon Dragon.
The basic purpose of a vertical fin is to prevent the aircraft from flying sideways through the air, especially when the pilot makes an aileron input, which tends to create adverse yaw.  Adverse yaw tends to be most pronounced in long-spanned, slow-flying aircraft.
Flying sideways is never efficient.
However, not all sailplane designers have always followed this philosophy.  The Scheibe Bergfalke is an example of a glider with a rather small vertical fin.  (Look closely at photos of this glider and you'll see that more than 75% of what appears to be the "tail" is actually the rudder, not a fixed vertical fin.)  When flown with the pilot's feet off the rudder pedals, it tends to be rather uncooperative in response to aileron inputs, being quite happy to fly sideways through the air rather than actually turning.
Keep in mind also that a given desired "tail volume"-- the product of tail area times moment-arm-- can be achieved with less drag with smaller tail on a long slender boom (rear fuselage), than with a larger tail on a shorter fuselage.  You've really asked two separate questions here-- "Why is the tail boom so long?", and "Why is the vertical fin so large?".  The first question is easier to answer than the second-- the tail boom itself creates relatively little drag, due to its slender cross-section and resulting low "wetted area".  To a first approximation, we can say that the tail boom is long so that the fin and horizontal tail don't need to be larger, to create the desired tail volume and flight characteristics.  In truth, the story is a little more complicated-- when we dive into the details of spiral stability theory, we find that extending the tail boom while keeping the "tail volume" the same actually does produce significant changes in the aircraft's flight characteristics, due to that fact that the airflow and "relative wind" are actually curved whenever the flight path is curved.1  This also means that for a given "tail volume", the drag reduction resulting from extending the tail boom and decreasing the tail area will be less in turning flight than in linear flight.
One reason that modern sailplanes are generally designed with much larger vertical tails than vintage sailplanes--or most single-engine general aviation aircraft-- is that the long slender tail booms used in modern sailplane designs have a very small cross-sectional area and thus contribute very little to the aircraft's yaw stability ("directional stability").  Nearly all of the required "weathervane effect" has to come from the tail itself.
Certainly the purpose of the long tail boom and large vertical fin is not to "balance" the weight of the cockpit.  Rather, the cockpit is placed in the optimum position to balance everything else.
Footnotes--

Re "the airflow and 'relative wind' are actually curved whenever the flight path is curved"-- another way to say this is to note that in curving flight, the aircraft is rotating as well as translating linearly, so at any given instant in time, different parts of the aircraft are moving through the airmass in different directions.  The instantaneous linear velocity at the nose and tail are different, and "tufts" or "telltales" at the nose and tail would not blow in the same direction.  Details of the effects of the curving relative wind are beyond the scope of this answer, but it may be interesting to compare and contrast the designs of competition-level radio-controlled model sailplanes versus "free-flight" model sailplanes.  Both have relatively long fuselages, but the former invariably have much larger vertical tails than the latter.  The latter must be designed to fly in stable circles with no pilot input, while the former are designed for good response to pilot control inputs.  The effects of the curving airflow in turning flight play a role in these dynamics.


Is the number of private pilots increasing or decreasing?

The statistics for the number of pilots in the US is fairly easy to come by, The Aircraft Owners and Pilots Association published a report on the number of FAA certified pilots. This shows a general static trend over the 10-or-so years preceding the report in 2011

Year    | Total Pilots
======================
2011    |   618,660
2010    |   627,588
2009    |   594,285
2008    |   613,746
2007    |   590,349
2006    |   597,109
2005    |   609,737
2004    |   618,930
2003    |   625,011
2002    |   631,762
2001    |   612,274

The graph shows the total number of pilots since 1929.

For Europe, this statistic is a little harder to come by. In general, Aviation in Europe is controlled by the European Aviation Safety Association to which pretty much all European countries are members, with a few having a working arrangement to sync up their procedures/licensing. The EU, and its associated agencies are typically bureaucracies at their best (worst!) and so there is unlikely to be a single register of the number of pilots.

For example, some elements of aviation (although NOT Licensing) is still managed by the UK Civil Aviation Authority. With all the various european and intra country agencies involved in European Aviation it will be tougher to get figures for the number of pilots.

Internationally your problem is moreso. With tens of different agencies involved in the Flight Crew Licensing, you may find it harder still to get some accurate figures.


Does Daylight Saving Time affect local airspace?

Aviation always uses UTC time. This is from the FAA's AIM, but other countries do the same for obvious reasons:

  4-2-12. Time

  a. FAA uses Coordinated Universal Time (UTC) for all operations. The
  word "local" or the time zone equivalent must be used to denote local
  when local time is given during radio and telephone communications.
  The term "Zulu" may be used to denote UTC.

This question covers in much more detail why UTC is used in preference to GMT, and this question explains why pilots need to know the time in the first place, at least under IFR (which applies to almost all airline flights).


Why is a straight-in approach not allowed to RWY 07 at Cluj (LRCL)?

It is allowed.
Runway 07 has a published GNSS straight-in instrument approach as of 10 Nov 2016.

Download link here, or click image for full size.
For non-GNSS equipped planes, there are no published straight-in instrument approaches for runway 07. Only the circling VOR 07.
However, in VMC the crew may request or likely be given a visual straight-in approach to 07.
As to why there aren't published minima for a straight-in VOR approach to runway 07, I can think of two plausible reasons:

VOR accuracy being not good in that quadrant, maybe due to terrain interference, or interference from the tall church on short final.
Winds almost always favor 25, so no effort was made to certify a straight-in approach using VOR for 07.

When an aircraft intends to land on a runway for which no instrument approach procedure exists, it may descend on the instrument approach to another runway and, provided the required visual references are established at the circling MDA/H, maneuver visually for landing on the desired runway. This procedure is used when landing on the instrument runway is undesirable, due for example to wind conditions or work in progress.
[...]
A circling approach is the visual phase of an instrument approach to bring an aircraft into position for landing on a runway which is not suitably located for a straight-in approach.
— skybrary.aero


How do different training paths to multi-engine rating compare?

At the end of the day the choice might be made for you, as many flight schools will not let you fly their multi-engine aircraft until you have a private licence.

People almost always begin on single-engine aircraft not just for cost, but also for efficient training. Multi-engine aircraft are complex beasts that require a lot of theoretical knowledge and practical skills to fly safely. If you're trying to get a grip on all that at the same time as just learning the basics of flying, you'll no doubt struggle and have to repeat lessons. Your first solo will definitely come considerably later, and many would agree that you learn the most about flying when you're up there by yourself.

Granted, the more multi-engine time you can get, the better your future job prospects (generally speaking). Just remember that doing your early training like that will increase the time it takes to get your ticket. For a qualified pilot, a multi-engine rating only takes 10-15 flight hours of training anyway, so to me there isn't a huge advantage in getting one before your private licence.


When instructed to report something.

ATC: Cimber 626 turn left heading 120, cleared ILS approach runway 09, report established
Pilot: Heading left 120, cleared ILS approach runway 09, WILCO, Cimber 626

ATC: OYABC airborne time 33, report passing Dalhem
Pilot; (Roger), WILCO, OYABC

ATC: Lufthansa 135, traffic is a Boeing 737 on 5 miles final for runway 09, report in sight
Pilot: WILCO, Lufthansa 135


Why is the use of reverse thrust not considered when calculating accelerate-stop distance on dry runway?

If your thrust reversers are operational and debris is not a concern, you're right for an in-service rejected takeoff (RTO):

  There's nothing that prevents the use of reverse thrust on a dry
  runway for an aborted takeoff.

Most in-service RTOs utilize reverse thrust if available (see this video for a dry-runway example).

However, in order to certify a transport-category airplane, one must show compliance with 14 CFR 25.109, paragraph (f), which precludes the use of thrust reversers on dry runways in calculating the accelerate-stop distance. The demonstration required by paragraph (i), therefore, cannot be conducted with reverse thrust on a dry runway. From a certification standpoint, the accelerate-stop calculation is made the way it is because that's what the regulations say. But why is the law written this way? See this video at about 1:12:

  The whole intent is to demonstrate [that] under [the] worst conditions you can safely stop the aircraft.

"Worst conditions" encompasses at least inoperative thrust reversers and worn brakes.


Was there ever a supersonic flight in a non-pressurized plane, and what is/would it be like for the pilot?

When you're in the cockpit, the sound you are hearing is vibrations of the skin and canopy/windows induced by the outside flow, transmitted through the air within the cabin to your ears.  A very loud hiss/roar (even in a normal jet, if you speed up to near Vmo, say .85 M, the noise level in the flight deck gets unpleasantly loud.  Go faster, and it's the same hiss/roar but the more energy being imparted means the sound level transmitted to your ears goes up).
When Chuck Yeager was going supersonic in the X-1, he could only tell he was supersonic was by the Mach Meter, not by the noise level.
If the cockpit was unpressurized, this doesn't really change because it's still just noise transmitted from vibrations of the skins/windows transmitted through air that is stationary relative to objects it's in contact with, so you're still just hearing a hiss/roar of the outer airstream passing by, supersonic flow or not. Just way louder, I'm sure, because of less sealing and insulation.
Any other sounds originating outside you would also hear to the extent that the sound waves from that sound impacted that skin and caused a change in the sound character being transmitted through the stationary air in the cockpit.  If the wave was intense enough, you should hear a thump sound of some sort, whatever was the result the pressure wave of the sound origin changing the transmitted energy passing through the still air in the cockpit at the instant it reaches the fuselage.
The key part is that the air within the cockpit is not moving with any speed, so it will transmit any vibration from the skins, windows, engines, pumps, etc to your ears whether you are supersonic or not.


Why and how do flaps increase the curvature of the wing?

Flaps change both the camber of a wing as well as its chord line and angle of attack. All the following images were taken from this article.

You can see the camber line here in a retracted scenario:

And here in an extended scenario:

As for the why, flaps are generally used to allow you to slow an aircraft down at a give pitch angle. This allows the pilot to pitch the aircraft down without an increase in speed. Generally a pitch down (given no other things are changed) will result in an increase in speed.

Flaps also change the angle of attack of the wing as well as the chord line:

All of this is a bit of an over generalization as there are many types of flaps and it's worth looking into the different types and how they operate.


Who decides how to "handle" an aircraft, with regards to severity of manoeuvres etc?

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.


As some have written in the comments, it is a Westbrook W-5-B Sportster.
Westbrook started as a company in 1929 and failed in 1931. Approximately five W-5 sportsters have been built:

[NC9N] c/n 501 destroyed in a 1931 crash
[853W] c/n 502,
[NC966V] c/n 503 lost in a 1938 accident
[NC92V] c/n 504,
possibly unlicensed one,  c/n 505,

source / further info: aerofiles.com / secretprojects.co.uk / all-aero.com

Munch & Romeo, Inc
The aircraft was shown on the business card of Munch and Romeo, which also shows the prices they charged for flight instruction:

I found evidence that one of the aircraft of Munch and Romeo was  involved in a mid-air collision in 1936:

Negligence -Collision -Insufficient Allegation of Agency.
-[NewYork]  In an action for damages arising out of a collision between
the plaintiff's airplane with that of the defendant as both were about
to land,the complaint alleged that the defendant's plane was being
operated by one Donahue with the consent and permission of the
defendant, and that the collision was caused solely by Donahue's
negligence. On motion to dismiss the complaint for failure to state a
cause of action, held: complaint dismissed, with leave to plaintiff
to serve an amended complaint within ten days.There were no
allegations that Donahue was operating the defendant's airplane as
his agent, servant or employee, or in the defendant's business
and within the scope of his employment. None will be inferred from the
allegation that the defendant was the owner of and in control of the
airplane.An allegation that Donahue was operating the vehicle with
defendant's con-sent and permission would be sufficient to charge the
latter in a case arising out of an automobile collision on a public
highway under §59 of the Vehicle and Traffic law, but the statute is
not applicable here. Consequently the common law rule governs, by which
it is settled in New York that the owner of a vehicle will not be held
liable for negligence of its operator unless at the time it was being
used in the owner's business by the operator within the scope of his
employment. Munch & Romeo, Inc. v. Caton, 96 N. Y. L. J.876, 235 C. C.
H. 1213 (County Court, Nassau County, New York, Sept. 25,1936).

source: Journal of Air Law and Commerce, Volume 8|Issue 1, Article  8 scholar.smu.edu

The company owned other aircraft as well; by 1936 they seemed to be active in aircraft trading as they tried to sell several aircraft in advertisements in Aero Digest, Volume 29 of July 1936

AERONCA C-3: New September 1935; 150 hours  total time ; just top
overhauled, A-l condition  throughout, SI. 425. Munch & Romeo, Inc.,
Hangar  7, Roosevelt Field, Mineola, New York.

1936 TAYLOR CUB: 2 months old, 35 hours total  time, \$1,195. Gee Bee,
Kinner K-5: 45 hours since  overhaul, \$875. Avian Cirrus, \$600. Also
Great Lakes,  Birds, Cessnas, Monocoupes. Munch & Romeo, Inc.,  Hangar
7, Roosevelt Field 1 , Mineola, New York.


What are pro/cons of steam as lifting gas for airships?

The main disadvantage is the energy required just to get off the ground. Let's do a back-of-the-envelope calculation, comparing this to a hot air balloon.

Let's heat 1m³ of air. To get equivalent lift, we need about 0.5m³ of steam.
The density of air is about twice the density of steam. So, for a given amount of lift, we need to heat approximately the same mass of lifting medium.

To heat 1kg of air to 100°C above ambient, we need about 100kJ (specific heat of air is about 1kg/(kJ K)).

To heat 1kg of water to 100° above ambient, we need about 420kJ just to heat the water. To vaporize the water, we need an additional 2250kJ, for a grand total of 2670kJ.

The most used hot air balloon size is 2800m³. For that we need to heat 1400kg water. Multiplying gives about 4GJ of energy or 75kg of propane just to get off the ground. Since we established steam can lift twice as much per unit of volume, we can maybe get away with 2GJ or 35kg of propane.

Some more negative thinking... Condensation on the outer shell seems like a very efficient mechanism to transport heat energy to the environment, only partially offset by the reduction in surface area compared to a hot air balloon due to the cube-square law. This may require more energy in flight than a hot air balloon. Closed-cycle operation (only heat condensed water, not 'new' water) is preferred due to the high energy requirement, so descending means you have to wait for enough water to condense or be willing to pay the price in fuel. Superheated steam is not safe (despite what your table says); the high heat capacity and enthalpy of condensation can result in serious scalding burns compared to hot air. All of these effects are of course much more pronounced when comparing to a helium-filled blimp.
Still, it's a really neat idea, and sometimes you don't need a practical reason just to build something neat.


Do airways with multiple numbers (e.g., J89-101) imply combined segments?

Yes, from your example J34-68-538 are jet routes that share a segment and aircraft on different routes may travel the same segments between waypoints. A complete explanation is in the FAA's Aeronautical Chart User Guide.


What are the differences between the Avro RJ85 and the BAE 146-200?

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

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


What does "ENG 2 REV PRESSURIZED" ECAM message mean in the Airbus A32F?

In case of Airbus A320 (A318/319/320/321) models, ENG 2 REV PRESSURIZED means that the thrust reverser system is pressurized. From FCOM:

ENG 1(2) REV PRESSURIZED
Reverser system is pressurized, while rev doors are stowed and locked with no deploy order.

The crew are expected to reduce the engine thrust to idle when possible in flight (also on ground).

Reverse thrust system is pressurized with reverser doors stowed and locked.
THR LEVER 1 (2) .................................. IDLE
lf flight conditions permit, reduce the thrust of the affected engine to IDLE as a precautionary measure.

You can see a case where this warning came on.
Deployment of thrust reversers in flight could have fatal consequences as seen in a B767 Lauda Air Flight 004 (note that the warning is about reverser pressurization, not deployment).


Why is the thrust/drag increase much lower at a lower FL with weight the only variable?

At a lower flight level the air density is higher, so a lower lift coefficient can be trimmed and the induced drag is a smaller fraction of total drag. Hence, the mass increase causes a much lower increase in overall drag.

At higher altitude the friction and pressure drag is lower but the induced drag is higher, so increasing the mass will cause a much higher jump in drag.

Now for the numbers: In FL 290 the indicated speed is 155.362 m/s, so the dynamic pressure $q$ is 14,784 N/m². I use surface area $S$ (124 m²) and aspect ratio $AR$ (b²/S = 10.33) from Wikipedia and guess that the Oswald factor $\epsilon$ is 0.8. Now the lift coefficient $c_L$ at FL 290 and 50 tons mass is
$$c_L = \frac{m\cdot g}{q\cdot S} = 0.2675$$
This allows us to calculate the induced drag:
$$D_i = q\cdot S\cdot\frac{c_L^2}{\pi\cdot AR\cdot\epsilon} = 5052\:\text{N}$$
which is just 1136 pound-force; about a third of what you give for FL370. This fits well with the given thrust increase at FL290 which is about ⅓ of the increase at FL370.


Can actual instrument time count as simulated instrument time for the PPL?

Provided your CFI and you were flying on a filed and ATC cleared IFR flight plan at the time of the real instrument time was acquired, then yes, you can use that instrument time toward your PPL Aeronautical Experience requirements.  It does not necessarily need to be done under the hood. 61.109(a)(3) just requires the applicant log 3 hours of dual instruction time flying solely on reference to the instruments, whether simulated or real IMC conditions.

The downside here is that unless you did the dual instrument time with a CFII, you cannot use that time toward an instrument rating or advanced pilot or flight instructor certificates per 61.109.


Can a turbojet jet or turbofan powered aircraft land and take off from water?

Yes, they can.

In service today:

The Canadair CL415 is a turboprop water bomber with water landing capabilities (typically, water skimming capabilities, to skim across a lake and refill).

The Shin Maywa US-2 is the latest in a series of rescue/maritime patrol aircraft that have been in service for some time. The design uses the engines and wing of a C-130, with an interesting STOL feature: ducts that blow air across the top of the flaps so that they can be set at a more extreme angle for extremely short takeoff.

The Beriev BE-200 has seen limited production in Russia. It uses high bypass turbofans, mounted high and behind the wings to protect the engines from water spray.

From the Soviet era, were the ekranoplan sea skimmers, that flew entirely in ground effects. All were turbine powered.

In a prototype stage is the AVIC AG-600 in China. Powered by four turboprops, it appears to be an upsized copy of the Shin Maywa design.

A one-off production flying today is the Doriner DO-24ATT, essentially a WW2 DO-24 maritime patrol aircraft that was re-engined with turboprops. It is currently flown by Claudius Doriner's grandson.

Four turbine powered amphibious/flying boat aircraft that were developed but never saw service were the Convair Sea Dart, Martin SeaMaster, Saunders-Roe Princess, and Saunders-Roe SRA1.


Why would 2 aircraft fitted with the P&W PT6 Engine have different top speed?

The P&W PT6 comes in many different varieties. The smallest PT have 500hp while the largest have 1700hp.  It is not the "same engine" as you state in your question.

The standard Caravan has 675hp while the other aircraft you mention have 1,200hp. That alone can account for the major difference in performance. Fixed gear and struts also add to an increase in drag and a reduction in speed.

The bottom line is they are different aircraft, with different engines, designed for different roles. There is no reason to expect similar speed or performance.


All of these methods are used.

Nosewheel steering is common on most commercial aircraft using a tiller.  Rudder, differential braking, differential thrust and even motors in the wheels (experimental only as far as I know) are also used, as seen in this video.

Engine thrust is used to move forward but differential thrust might also be used when negotiating tight turns. (Details here)


If two aircraft (let's call them Aircraft A and Aircraft B, since this isn't specific to 777/787) share a type rating (technically known as a "common type rating"), it means that, if a pilot is already certified to fly Aircraft A, and wants to get certified to fly Aircraft B, they only have to take a course on the parts of Aircraft B that are different from Aircraft A.  If Aircraft A and Aircraft B didn't have a common type rating, an Aircraft A pilot wanting a certification for Aircraft B would have to train for every part of Aircraft B, even if many, or even most, of those parts were exactly the same as on Aircraft A.

As you can imagine, getting two (or more) aircraft types a common type rating can save quite a lot of training time and money for pilots switching from one to the other.

Grossly-oversimplified example

Our aircraft:

Aircraft A is composed of parts A, B, C, D, E, and F.
Aircraft B is composed of parts A, B, C, G, E, H, and I.

Our pilots:

Grace is certified to fly Aircraft A.  She wants to become certified to fly Aircraft B.
Tedd is certified to fly Aircraft B.  He wants to become certified to fly Aircraft A.

Scenario 1: Aircraft A and Aircraft B do not have a common type rating

To gain certification for Aircraft B, Grace has to take courses on parts A, B, C, G, E, H, and I.
To gain certification for Aircraft A, Tedd has to take courses on parts A, B, C, D, E, and F.

Scenario 2: Aircraft A and Aircraft B share a common type rating

To gain certification for Aircraft B, Grace only has to take courses on parts G, H, and I.  She doesn't have to take courses on parts A, B, C, or E, since those parts are the same as on Aircraft A, which she's already certified on.
To gain certification for Aircraft A, Tedd only has to take courses on parts D and F.  He doesn't have to take courses on parts A, B, C, or E, since those parts are the same as on Aircraft B, which he's already certified on.

Real-world example

The A330 and A350 share a common type rating (but the A340 doesn't, because different number of engines); as a result, whereas (say) a 767 or A300 pilot wishing to gain A350 certification needs 23 days of comprehensive training on every aspect of the A350, an A330 pilot has to take an eight-day course to become an A350 pilot.  This eight-day course, covering only the parts of the A350 that differ from their counterparts on the A330, is, appropriately enough, termed "differences training".  (Source)


What does "the other's right" refer to in 14 CFR Part 91.113?

You wrote that:

it would seem both aircraft will either perceive themselves as being to the left or right of the other meaning either both aircraft or neither aircraft would have the right of way.

But that's only the case if the two aircraft are approaching head-on, or nearly so, and the FAR you quoted already accounts for that situation:

Converging. When aircraft of the same category are converging at approximately the same altitude (except head-on, or nearly so), the aircraft to the other's right has the right-of-way.  [Bolded emphasis mine.]

If the aircraft aren't approaching nearly or actually head-on, one aircraft will be unambiguously on the right:

As an extreme example, take the case of two aircraft "approaching" each other on side-by-side parallel courses in the same direction.  Obviously, in this situation, one aircraft will be on the right (and have the right of way).

(Red and blue are each a different scenario.)

Now consider two aircraft approaching each other on perpendicular courses (with a 90° angle between the two).  One aircraft's pilot will need to look to the left to see the other aircraft, and the other aircraft's pilot will need to look to the right to see the first aircraft.  The aircraft whose pilot has to look left is the aircraft on the right, and they have the right of way; the other aircraft is to the left of the first aircraft, and will have to give way.

Even if there's a 135° angle between the two aircraft's flightpaths, one pilot will still be seeing the other aircraft noticeably left of the center of their windscreen; this pilot's aircraft is on the right, and has the right of way.  The other pilot will have to look through the right side of their windscreen to see the first aircraft; the other aircraft is on the left, and has to give way.


What is defined as "day VFR" under EASA rules?

It's by opposition to Night VFR (NVFR) which allows to fly by night in visual meteorological conditions. So the answer will focus on NVFR, rather than on day VFR.

EASA harmonization over EU countries is done by enforcing Standardised European Rules of the Air (SERA). SERA states that a night flight must be conducted in IFR, and therefore the crew must hold an Instrument Rating.

Prior to SERA, some countries did not allow VFR at night for security reasons (aircraft not visually identifiable, and no transponder), but other did, that's the case for the UK that I'll use as an example here.

When implementing SERA, EU countries can use acceptable means of compliance, as described in ED Decision 2013/013/R and its annex.

NVFR is implemented (or denied) in EU country by country. So rules may differ between countries. UK example:

UK license can be extended for NVFR.
More for UK NVFR: Safety Notice: SN-2012/007.
In practice, VFR at night is permitted in accordance with SERA requirements. Aircraft leaving the vicinity of an aerodrome must maintain 2-way communication with ATC and file a flight plan. The process of 'booking out' is still accepted as an alternative method to filing a formal paper or electronic flight plan in certain circumstances. Similarly, abbreviated flight plans filed in flight are still permitted. There are also more restricting weather minima:

Minimum cloud ceiling of 1500 ft AMSL
Flight visibility of 5 km, or 3 km in the case of a helicopter flying outside controlled airspace
Maintain sight of the surface when flying at 3,000 ft AMSL or below
Minimum height of 1000 ft (or 2000 ft if over high terrain) above the highest fixed obstacle within 8 km of the aircraft except when taking off or landing

Night is defined for  this purpose:

e.g. for UK in Air Navigation Order 2009 Art. 255:

  'Night' means the time from half an hour after sunset until half an
  hour before sunrise [...] at surface level.

Aircraft must be compliant for NVFR, e.g. this equipment is required:

artificial horizon
Instrument Lighting
Landing Light
Position and Anti Collision Lights

In countries where NVFR is not allowed, IFR applies at night.


When did airlines start using seat belts for passengers?

The world's first airline used Zeppelins, and there was no need for seatbelts.

In WW I seatbelts were standard issue for pilots, at least in Germany.

After the war, the airlines used seatbelts irregularly. Below are two pictures of the cabin of the Junkers F-13, the first all-metal passenger aircraft, which was first operated in 1919.

Junkers F-13 cabin, front view (picture source)

Junkers F-13 cabin, rear view (picture source)

While the belts on the front seats are clearly visible, the rear seats seem not to have them. If the picture date (Oct. 10, 1919) is to be trusted, they were used right from the start in 1919. The way they are fixed to the wicker seats, however, looks rather flimsy and will not give much protection in a crash.


What would happen if pilots were locked out of the flight deck?

The flight deck door lock system is normally turned on while on the ground and remains on for the entire flight. Once the system is turned on, the door DOES lock automatically when closed and can only be opened by the pilots in the flight deck.

If both pilots left the flight deck, the door would lock automatically behind them unless the door lock system was first turned off. There are procedures in place which can allow the door to be unlocked from the cabin in case no one in the flight deck can open it due to incapacitation.

The pilots can also over-ride this unlocking procedure in case they suspect criminal interference or un-authorized entry attempt.  This over-ride feature prevented the Captain of Germanwings 9525 from re-entering the flight deck as the suicidal First Officer deliberately crashed the aircraft killing all on board.


Is English sufficient for international aviation?

ATC and pilots must be able to communicate in English on international flights involving ICAO member states. There are 191 countries that are members of the ICAO, covering almost all of the world.

While communications may be performed in the local language, English must be used upon request on international flights. Controllers and flight crew engaged in communications for international flights should be proficient in spoken English in addition to English aviation phraseology.

Some domestic airways and airports may require communications in the local language instead of English.

So English is sufficient if you stick to international airports and airways, but be sure to check the language requirements before you venture into foreign domestic airspace and airports.


Is it true that they must dump excess fuel before they land?

Nope. You don't siphon your car just before your destination. Fuel is money.

Except in emergency in big planes, fuel then is a potentially lethal burden (weight).

  ... in case there's a problem with the landing and they need to abort?

Contingency fuel just for aborted landings, weather deviations, etc., is added during the fuel loading for such things. You get to keep it at the destination.

Further reading:

When are aircraft required to dump fuel for emergency landings?
Can a wide body airliner land safely with a full fuel tank?
Fuel planning—fuel calculation


Why do airlines seem to go out of business suddenly?

Mainly because winding down airline business will turn it into a sudden and from there on increasing loss. Airline operation nowadays is calculated in most cases toward a rather high plane utilization. Even more so on low cost enterprises. Sometimes even 10% less passengers may turn a profitable flight into a loss.

Airlines depend on filling up flights - until the last seat and last moment (last minute bookings being, depending on the business plan, even being more profitable). As soon as an airline would announce the intention to close down, new bookings will dry up quick, making next to every flight after this unprofitable.

This all is due the fact that, unlike a brick and mortar store, most cost of an airline are operational cost. There is no valuable inventory to be sold of over time, or much existing machinery to be run until the last moment to convert existing materials in (somewhat) higher valuable products, to turn it into cash. For Airlines there is none (No, collector value of in flight magazines don't really count), so shuting down the flights removes next to all further expenses, stoping any further increase of debt.

Not to mention, that flying after such an announcement would become almost impossible as each and every supplier would demand cash payment from that moment on - with airport fees and fuel payment most prominent - something a money strapped airline hardly can provide. Airlines that tried to go that way usually postponed the shutdown just by days - and often with planes stuck in all corners of the world, unable to return, not able to sell them, but instead adding more debt in airport parking fees.


Why are magnetized materials dangerous goods?

98% percent of magnets - the everyday ones - are completely harmless. I believe the concern is with super-strong rare-earth magnets, where they can be problematic. Aside from Simon's valid point on interference to compasses:

Getting stuck to things, such as other bags or the infrastructure itself, in the baggage system.
Attract themselves to other packages and content, possibly damaging these. Think of hard drives and electronics.
Being a nuisance and safety concern should somebody decide to open it, such as customs or security. You can get your hand crushed in the process if you open the box and the thing springs out.

Be aware they do not appear to be banned - just regulated in that they have to be properly labelled and packaged for safe transport. More curiously in that list are 'First Aid Kits' and 'Seatbelt Pretensioners'.


Can I become a pilot if I am under treatment for Attention Deficit Disorder?

I'm going to assume you're asking about US/FAA requirements - If not what's below may not be particularly helpful.

ADD is not a disqualifying condition, however if you have a formal diagnosis of ADD or ADHD you may need to undergo additional testing in order to receive a medical certificate.
Also some of the medications used to treat ADD/ADHD may be disqualifying (I know that Adderall, Focalin, and Ritalin were all on the FAA's "No Fly" list - I'm not sure if they're still an absolute NO or if you can get approval for them).

AOPA has a pretty decent drug list that you can search to see if what you've been prescribed is permitted - it's a little easier to search/cross-reference than the official FAA "Do Not Issue/Do Not Fly" list and they do a good job keeping it up to date, and a brief article on ADD/ADHD & medical certification.
They also have a service to assist you with getting your medical (as part of Pilot Protection Services) which can be helpful.


Is a turbocharged piston aircraft the same thing as turboprop?

They are both internal combustion engines that have a turbine in their exhaust that is used to power a compressor to pressurize the air before it is used for combustion.

In the turboprop, the turbine also powers the prop.  In between the compressor and turbine, the fuel/air mixture is burnt without significant moving parts.  Without the turbine and compressor, a turbine engine is essentially a tube with heating element in it.

In a turbocharged piston engine, you have an otherwise normal piston engine which turns the prop.  The turbine is in the exhaust from the piston engine and powers the compressor pushing air into the piston engine.  The turbine and compressor are not connected to the prop though.

Here they are as diagrams along with some other types of engine.


The "QS" first stood for quarter share, according to the 1998 issue of Flying. Each aircraft will have multiple owners to help bring the cost down for the owner.


Does ATC direct flights to fly eastbound at odd levels and westbound at even ones?

In addition to ymb1's excellent answer, here are a few thoughts from the controller perspective.

Various rules and regulations for cruising level allocations exist. For flightplanning purposes, the semicircular rules are very notable. As pointed out by ymb1, the exact rules vary from place to place. In some regions, flights flying on a westbound track shall plan to fly at even levels while flights flying eastbound shall plan to fly at odd levels. Note that this is in relation to the magnetic track of the aircraft, except in areas near the poles. In some countries it is the other way around, in others, the rule is north/south instead of east/west.

Example of a general east-odd/west-even rule (excerpt from AIP Denmark)

You can also have specific ATS routes, such as airways, that require you to flightplan certain levels that deviate from the general rule.

Example of ATS route which enforces even levels for eastbound flights (excerpt from AIP Germany)

It is important to note that rules for level allocations are mainly used for planning purposes. When filing a flightplan, the planned levels must obey any such rules - and you should always stick to your filed flightplan when in uncontrolled airspace.

However, when being provided with air traffic control service, the controller may deviate from the general rules if so desired (unless the local operating procedures do not allow it). If I have an upcoming conflict that can be solved by climbing a westbound flight to FL370, then I will be more than happy to do so - especially because establishing vertical separation is often the easiest way of solving a conflict. As long as the flight is within my sector, then I make the rules, so to say.

Example of ATC radar screen with eastbound traffic (SAS528) flying at an even level (FL340) for separation

When transferring a flight to the next sector (or another unit), the controller is responsible for making sure the flight is at an appropriate level in accordance with the local letters of agreement. Principally, this means that we have to go back to the published rules (east odd, west even or specific airway rules). In practise, though, if it is desired to transfer a flight on a non-standard level, all it takes is a phone call to the next sector to check if they can accept it. If the next sector has no conflicting traffic, then there is nothing wrong with keeping the flight at a non-standard level.

So to sum it up, when planning a flight, you have to obey the published level allocation rules, which vary from place to place. A large part of the world uses the east-odd, west-even rule. But once under ATC control, there is no need to worry if you are assigned a non-standard cruising level - if that happens, it is because it is allowed and has been coordinated.


Why would the USAF have no support for autolanding?

FWIW, I do not fly the KC-10, but I do have friends that do...

Anyway, you're looking at a T.O. that is 7 years old since the last change (not sure when the most recent write-in is)...  Military pubs are always changing, avionics upgrades are always happening, and what you're looking at may be severely outdated.

Having said that, I don't believe in this instance that it is.  However, I don't see the need to be able to shoot CAT IIIc approaches.  What does the Air Force gain?  Once deployed you aren't going to have that technology, and CONUS you just divert.  So why spend the money for it?

I may not know the full politics behind it, but I do not see the operational need for it.


Given an exact date, time, and coordinate, can I locate a plane that flew overhead?

I recommend using flightradar24. In addition to its many other features, it has a playback mode. I'm not sure if there is a simple way to view a specific coordinate; however it should be easy enough to navigate to your desired location using the map view. If looking at coordinates is a must, I have found that you can put them after the url like so:
https://www.flightradar24.com/-36.38,128.09
Edit
According to Jan Hudec, you need a flightradar24 subscription to access dates this old.


What could cause GE and Rolls-Royce turbofan engines to sound different?

The GE90 engines have a higher bypass ratio than the RR Trent.

The majority of engine noise, especially the "ripping, howling, typical jet noise" comes from the engine core.

The higher the bypass ratio, the less air passing through the core for any given thrust and the more cold air meets the core exhaust at the back reducing the shear

Jet engines with no bypass ratio and deep intakes produce a wonderful sound


Why do I never see fighter jets on sites like FlighRadar24 and ADBSExchange.com

Because they don't want to be seen.

  Are fighters allowed to just turn off their transponders in civilian airspace?

FR24 and ADS-B Ex are not based on normal transponders (that would require access to actual RADAR data) but rather ADS-B and mode-S transponders. The military can simply choose not to operate with this equipment. This does not make the fighters invisible on normal ATC radars, since ATC obviously still needs to be able to see them.