A slat is a retractable version of a device known as “leading edge slot”. It is basically a slot just behind the leading edge.

When an airplane is flying slow, it will probably either be somewhat nose-up to maintain level flight, or be descending, or somewhere in between. In either case, the air strikes the wing at a higher angle than when the plane is facing forward and flying straight at high speed. The angle with which the air hits the wing is called the angle of attack.

On the surface of the wing, there is a layer of slow-moving air called the boundary layer, caused by friction between the wing and air. This boundary layer makes the wing appear thicker than it is, particularly towards the back, since the air piles up toward the back. The faster airflow prefers to flow around this boundary layer, instead of through it/around the foil, meaning the fast-moving air is turned less, and so produces less suction at the top of the foil.

At the trailing edge, this boundary layer terminates in turbulence, and creates more suction at the back. Obviously, due to the curvature of the airfoil, the backward side of the top of the wing is more angled towards the back and less upwards, so having suction in that region creates more drag and less lift than having suction further forward.

In effect, due to the boundary layer, the airflow around the wing “sees” the top rear portion of the wing bulge out more than it actually is. The resulting “shape” of the wing is flatter at the top, creating less lift, and has a blunter, steeper trailing edge, creating more drag.

At the higher angle of attack mentioned above, the boundary layer over the top of the wing is even thicker, since, as you can guess, the airflow around the wing would be slowed more on the more difficult journey. Eventually, at very back, the direction of airflow in the boundary layer may reverse, (this is what is called flow separation) creating even more turbulence and increasing suction in that region even more, making something that is bad worse.

With increasing angle of attack, the boundary layer continues to thicken, and the zone of separated flow expands forward, eventually there will come a time when the wing “bulges” out so much it no longer produces an increase in lift, but produces a lot of drag. This is a stall.

The slot behind the extended slat lets in more fast moving air, speeding up and thus thinning the boundary layer.

So, what is the difference between flaps and slats?

Flaps deflect air already flowing past the wing downward. Slats enable fresh air to flow over the wing. (NOTE: there are flaps with slots in them. These slots work the same way as slats.)
Flaps can work at zero angle of attack. Slats can't.

Also, just a clarification for the OP about the “droop”. Leading edge droop is exactly what it sounds like. It gives the air a smoother journey over the wing at high angle of attack, increasing lift. But at low angles, it produces negative lift.....


It's the second option. In any other context, a small aircraft's electrical system would be called "24V". But the alternator regularly puts out 28V, so that's what's typically expected if you hook up your multimeter while the engine's running. Of course, the on-board equipment can operate over a wide range of voltages, often down to as little as 20V.


I accidentally deviated from an ATC instruction as a student pilot. How bad was it?

Well, you screwed up, but nobody got hurt, no metal was bent, and since the tower didn't yell at you presumably you didn't obviously endanger anyone's safety (though there's always some level of risk when an aircraft isn't where the tower expects it to be).

As far as deviations go, that's not good, but it's not terrible. The tower was probably expecting you to report 3 miles out, continuing in to about a mile from the field for your downwind.

Schedule an extra half hour of ground time with your CFI before your next flight to talk about what happened. Also take the time to fill out an ASRS report explaining what happened and why (It's probably unnecessary in this case, as a student the tower will almost certainly be satisfied with you getting "a good talking-to" from your instructor, but it's a good way to learn how that system works.)

There are a couple of other things you might want to do on your next few training flights:

Spend some time getting comfortable in the pattern on windy days.
You should be comfortable in a tighter pattern than 3 miles, even on a windy day (see my next item for why). This takes practice, and fortunately for you it's spring (at least in the USA) so there are plenty of windy days in most of the country!
Practice some engine-out approaches to get a feel for your plane's glide performance.
A base leg 3 miles out in a typical GA trainer is very wide -- Remember you generally want to be able to make some spot on the runway if your engine quits on downwind, and you probably can't do that from 1000 feet AGL at 3 miles out.
Take a few laps around the pattern and have your instructor pull the power at various points so you have a feeling for how the energy management works out - this will give you a good feel for how wide your pattern should be.
Turn the GPS off and practice flying visually.
The GPS is one link link in your error chain, but I think it's a big one: If you were flying visually and relying on landmarks to judge your distance rather than the 3 mile alert from your GPS you might have realized "Hey, I'm entering downwind - I should tell the tower!"


What additional considerations do pilots have when deviating from the planned routing on flights dispatched under Method 2?

As a Former Dispatch Examiner and an Airline Part 121 pilot for most of my career I think what you are looking for is this:

Unless the terrain is such that they must adhere to or close to the desired routing and they are notified of this, most deviations are inconsequential. It also depends on how many engines are on the aircraft. A twin engine aircraft must land at the nearest suitable airport in the point of time after an engine failure. Although it is wise to land with a greater than 2 engine aircraft, that is not the requirement. If an engine fails after takeoff before reaching cruise altitude the PIC should consider terrain clearance in his decision to continue, deviate or return. The PIC is responsible for his decisions and can deviate or not deviate if he feels his decision is as safe as the alternative. After drift down, most jets should clear all terrain with few exceptions but he should always consider obstacle clearance.

Remember everything in preflight must meet regulatory criteria. Once airborne the real world situation can alter and often does alter planning and some regulatory requirements. A lot of planning regulations go away after takeoff. The PIC is the final authority in all decisions after departure even though you both are considered responsible and should agree. If the crew has time to coordinate with Dispatch, then it is the dispatcher's job to warn the crew of all known hazards they may have overlooked while dealing with the in-flight problem even if they were briefed prior to takeoff.


When departing IFR, when do I switch from Tower to Departure?

When operating within class D airspace (operating Air Traffic Control Tower) pilots are to maintain communication with the tower until instructed otherwise.

On an IFR flight departing from a tower controlled airport, the tower controller will instruct the pilot when to change frequency to contact the next controller (the IFR Departure Controller).  Remain on the current frequency until instructed to change.

Here is an except from the pertinent regulation (FAR Part 91):

  §91.129   Operations in Class D airspace.

  2) Departing flight. Each person—

  (i) From the primary airport or satellite airport with an operating control tower must establish and maintain two-way radio communications with the control tower, and thereafter as instructed by ATC while operating in the Class D airspace area;

Note: It should be noted however, that in the U.S., departing IFR military turboprop/turbojet aircraft (except transport and cargo types) will be instructed to "change to departure control frequency" before takeoff. [ref:FAA JO 7110.65, paragraph 3-9-3 a. 2.]

This requirement allows pilots of single-seat high-performance aircraft, as well as certain other military aircraft, the ability to avoid being distracted by changing to another (e.g., departure control) frequency immediately after takeoff.  Further, many military fighter type aircraft used to have (probably some still do) radios positioned in the cockpit in a location that requires looking down or moving the pilot's head/eyes in such a manner that might cause momentary disorientation, which is not a good idea right after takeoff and close to the ground.

U.S. military control towers and some (perhaps most) joint-use military/civilian control towers have an "override" frequency (same frequency as the departure controller uses), for use in case some emergency situation that occurs just before, during, or immediately after departure requires urgent communication with the pilot (e.g., engine fire on takeoff noted by the tower, or similar type situation).


If cleared to cross a runway and expedite but are slow to get away, are you obliged to stop?

If you feel you cannot safely comply with any ATC instruction, you can simply reply “Unable” and the controllers will amend your clearance.  Remember: you are pilot in command; you are the final authority on the operation of that aircraft.

So the scenario might play out as:

ATC: “Bigjet, cleared to cross Runway 36.  Expedite crossing and report clear.”

Bigjet: “Cross runway 36 and report clear, Bigjet.”

Bigjet: “So-And-So Ground, Bigjet, Unable.  I’ve got a problem here.”

ATC:  “Bigjet roger hold short of Runway 36 for arriving traffic.  Will you be able to taxi after traffic clears the active?”


How does a pilot select the correct ILS when the airport has parallel runways?

The two ILS approaches on parallel runways will have a different ILS Localizer frequency. The pilots will select the correct approach from the charts and then either manually tune in the correct frequency or (for more modern aircraft) select the approach in the flight management computer, which will then automatically tune the correct frequencies. Before actually flying the approach, the pilots will cross-check the morse code identifier either by listening to it or (for more modern aircraft) by reading it off the displays.

Below you can see the ILS charts for the Runway 27L and 27R approaches at London Heathrow (source). I marked the frequencies and the identifiers (as they will be displayed on the screen, the morse code is depicted below).


How can a pilot involved in serious accident remain unknown?

In this case, it's most likely that the source for the story (the airline?) simply chose not to name the pilot and the editor of the Wikipedia article didn't seek another source that might have done so.
It's virtually certain that the pilot's name appears in the official reports of the incident.  The airline likely chose not to give the name for PR or legal reasons.


What is the history behind CAR 105.01(2)?

In short, it's because of complaints about noise. From the Canada Gazette, Vol. 132, No. 2, pp.98-103:

  The regulation reflects the Minister’s desire to have increased
  oversight of sightseeing flights within the Québec/Jean-Lesage
  International Airport control zone.

  [...]

  The regulations are
  intended to prevent frequent low level flights for aerial sightseeing
  purposes over the built-up area within the Québec/Jean-Lesage
  International Airport control zone and to stop commercial
  passenger-carrying aerial sightseeing flights from using the Lac
  St-Augustin, Quebec aerodrome for either take-offs or landings. The
  prohibition of low level commercial aerial sightseeing flights within
  the entire Québec/JeanLesage International Airport control zone is
  intended to ensure that such operations do not relocate to another
  nearby lake and recommence sightseeing operations from that location.

  [...]

  Since the late sixties and, increasingly, in recent years,
  Transport Canada has received numerous complaints from citizens about
  the noise of floatplanes flying over several towns and cities in the
  Quebec City area.

The Gazette goes into a lot more detail about the background, impact, consultation process etc. 25 local mayors signed a letter to Transport Canada asking for action, so I guess it came down to political pressure in the end.


Would the twin engine Boeing Y3 be able to compete better than the Airbus A380?

The answer is quite simply, no, at least, not if it is or was intended to compete as an airliner of roughly the same size.

That's because your question is based on a false premise, that the struggles of the A380 in the current market are due to its fuel economy.

The A380 is indeed uneconomic to operate except on few routes, but that is because of its size and capacity - which on most routes, can't be filled.

The market has changed since the A380 was conceived and launched; airlines are using more and smaller aircraft with more connections, between more minor airports.

To a lesser extent, new regulation has made a difference too. It has allowed smaller aircraft with twin engines - which are more flexible in an airline's operations - to take on routes that previously were considered suitable only for four-engined aeroplanes.

The technology and fuel consumption of the A380 are perfectly adequate to serve for decades into the future. It has been overtaken not by technological advances in its rivals, but by forces that change much faster than technology can: market conditions, and regulation.

Aircraft that will be selected instead of the A380 by airlines won't be chosen because they have better fuel economy (and even less so, marginally better fuel economy because they have two engines rather than four) but because they fit market needs better.


Why does the spanwise flow along a swept wing not accelerate?

In chordwise direction there is a curvature that accelerates the flow. In spanwise direction there is no such curvature.
See this answer for a more elaborate description of the lift generation.


Would an A320 override the autothrottle due to an erroneous radio-altimeter?

The Airbus thrust levers can only be moved manually. The levers do not move on their own to reflect the auto-thrust setting.

There are detents for the different modes of auto-thrust operation. Regarding the RETARD mode whereby the thrust auto-idles, Airbus doesn't use that (except in autoland).* Hence the callout, "RETARD, RETARD," for the pilots to retard the levers before touchdown.

In a normal uneventful flight, the third detent from the top (CL) is where the thrust levers stay throughout the whole flight from thrust reduction after takeoff, to just before touchdown.

(A320 manual)

* Airbus released an Operations Engineering Bulletin (no. 38) in Mar 2011 (also see the Airbus brochure on the matter). What happened to the Turkish 737 could happen to an A320 due to an "erroneous radio altimeter height indication".

Still, in the scenario given once the pilot flying had applied full power (TO/GA detent) it would have stayed there (unlike the Turkish 737).

Thanks to @user40476 for bringing up this autoland feature, which made me look up further details.


Why am I getting unusually high CHT on ground operations on one engine in a Seneca II?

If the gauges are good (swap them to see if the problem moves to the other engine), the baffling is good (baffles must be tight to the fins to force air between them with no leaks around the plenum), the cowl flap works normally (not being unknowingly blown partly closed by loose linkage), the most likely cause is an intake leak that's causing the cyl with the probe to run lean.
Either the rubber intake hose is bad, the gasket at the cylinder is leaking, or the sheet metal intake tube to which the hose connects, that is swaged into the intake spider tubes at the oil sump, is leaking.
This is an old problem on Lycomings. The little sheet metal pipe stub  is installed with a rolled bead that engages with a female groove in the hole in the sump, and depends on interference for a seal.  They can lose the interference and start to leak (you will be able to move it if you loosen the rubber hose).  There is a (very expensive) swaging tool (I believe you can rent from Lycoming) that re-rolls the bead from the inside.  Some people prefer to just remove the sump and send it somewhere to be done.
Although the redline is there, you really want to keep CHTs below 400F if at all possible.


Is there a legal requirement for planes to start from the ground?

At least in the US, this is perfectly legal. There have been quite a few such aircraft in history.
However, an aircraft docking and undocking from another is so rare that there's no standard way of communicating it with ATC. So you'd have to explain what you're doing in plain language. (And then you'd have to explain it again when the confused controller replies, "What?") If I were flying such a mission, I'd contact the local FSDO ahead of time to explain it, so that they can forward the information on to the local ATC facility to cut down on confusion.


Why are piston engines for aircraft rarely diesel powered?

You are right, there are few modern aerodiesels around - so few in fact that we can go through the brief list one by one:

Thielert: This is a development based on Mercedes-Benz car diesels, of which more than 1500 1.7 liter engines were built. Currently, a 2.0 liter engine is offered. The original Thielert company went bankrupt in 2008 and has been taken over by Continental.
Austro-Engine, another conversion of a car diesel for aircraft use. It is the result of the disappointment of Thielert's main customer, Diamond Aircraft, with the record of Thielert's initial Centurion 1.7 engine.
SMA:, a French turbocharged diesel with 5 liters displacement. Currently, around 100 of them have been delivered after almost 20 years of development work.
Zoche: The product of a father-son team with many clever details, but a quarter century of development work has not yet resulted in an airworthiness certificate for their two-stroke radial diesels. While Zoche claims to be the victim of a conspiracy by the authorities, the accused complain that the engines could not keep their cylinder heads on for long enough.

What has held the diesels back for so long?

Cost: Development in aviation piston engines has effectively stopped with the jet age. The existing designs were simply good enough until fuel prices went through the roof. This made diesels only attractive in niches, and as a consequence, production runs were far too small to justify the major development effort. Aviation engines run constantly at around 70% of their full power, so regular car engines could not be used without heavy modifications. As a consequence, a conversion kit can cost you $89,000!
Weight and complexity: The higher compression ratio of 1:30 requires a heavier structure, and fuel injection, a gearbox and turbocharging push the part count well above that of a gasoline engine. Once you compare system mass (fuel plus engine), the diesel wins only at ranges which are now mostly flown by jets. Yes, fuel flow is less (10 gallons per hour for a diesel against 13.5 gallons per hour for a comparable gasoline engine), but will only help at ranges above a couple of hundred miles.
Vibration! With that compression ratio, every ignition causes a three or four times heavier jolt to the engine and the aircraft structure. Not only the engine, but the whole aircraft structure needs to be designed with that in mind.

To be fair, a modern gasoline engine will also benefit from fuel injection, a gearbox and turbocharging, and Zoche initially did not use an electric system, relying instead on pressurized air for starting the engine (a pressure bottle loses much less of its stored energy when cooled to -20° than a battery, after all), but the practical aerodiesels are a lot more complex than the engines they are meant to replace, creating an obvious reliability disadvantage.

Thielert Centurion 1.7 in a Diamond Twin Star (picture source)


Was the March 2019 Rafale jet ejection incident investigated?

Here are a few key points translated from the media coverage on the official BEA report (PDF, in French):

The passenger was a 64 years old manager of a shipping company.
The French Air Force carries out such passenger flights occasionally.
The passenger wore a pulse watch which recorded between 136bpm and 142bpm prior to the flight, safe to say the man was under a lot of stress.
The report states that the situation produced significant peer pressure on the passenger: A significant number of colleagues from work, who had organized the event, were present.
In order to max the element of surprise, the passenger passed the required medical exam the same day. (As a consequence of this accident, there is now a 10 day mandatory delay between the exam and the actual flight.)
The physician issued the medical certificate under the condition that the flight must not exceed 3G. This information, however, did not reach the pilot due to what the report calls a "technical problem". (This type of aircraft reaches close to 4G during a normal takeoff.)
The passenger wasn't correctly equipped: The anti-G trousers as well as the chinstrap were too loose, the helmet visor folded up. The passenger lost his helmet mid air after the ejection.
The passenger ejected in a phase of the takeoff with negative G forces.

Most likely, the passenger was under an extraordinary amount of stress and tried to hold onto something in negative G, unfortunately the eject cord.

There's, however, another not so fun fact:

The pilot should have been ejected automatically along with the passenger. This mechanism failed! The pilot could have ejected himself nonetheless, but chose not to. It was due to this technical malfunction that the French Air Force didn't lose such an expensive machine.

(sources: Le Point, BFM TV)


What's the difference between Free-Flight and Free-Route?

The difference is between the definition itself.

  Free Flight : Free flight is a developing air traffic control method that uses no centralized control (e.g. air traffic controllers). Instead, parts of airspace are reserved dynamically and automatically in a distributed way using computer communication to ensure the required separation between aircraft. This new system may be implemented into the U.S. air traffic control system in the next decade.[citation needed] Its potential impact on the operations of the national airspace system is disputed, however.

This effectively means that, if a part of space is reserved for free flight, you can effectively do anything with your flight plan. Moreover this reserved space would change dynamically, so if there is an approaching aircraft nearby., your free flight space changes to accommodate free flight space for the other flight as well. Both of the planes would have DIFFERENT free flight space, and they can adjust their flight plan just in their own flight space. This eliminates the need for ATC completely.

  Free Route Airspace : Free Route Airspace (FRA) is a specified airspace within which users may freely plan a route between a defined entry point and a defined exit point. Subject to airspace availability, the route can be planned directly from one to the other or via intermediate (published or unpublished) way points, without reference to the ATS route network. Within this airspace, flights remain subject to air traffic control.

Here, the Airspace allotment remains under the control of the ATC, which allocates single space to multiple planes, and there one can decide which path to take. Here, inherently there is a possibility of overlapping routes (Because of the same airspace being allotted to multiple planes), and thats why, some routes are allowed in this space, and some are not.


Why aren't 3-surface aircraft more popular in general aviation?

Canards are not used in general aviation simply because they have complexe interaction with the main wing which can leeds to issues with stability and being at the front of the CG their effect on flight dynamics may be highly unintuitive in some situations. Therefore you need electronic control to adapt the pilot input to the control surface in order for the plane to fly as expected, and that's why in my opinion it was not suited to GA where electronic was expensive until the past few years. But they are plenty of jet fighter using them as they have the ability to greatly increase performance and maneuvrability.
In addition 3 surface aircraft means more wetted aera thus more drag, complex design and control, more mechanical moving parts which will often drive the price up.
You can find more information looking at the patent issued in 1988 by Piaggio here : https://worldwide.espacenet.com/publicationDetails/description?CC=US&NR=4746081A&KC=A&FT=D&ND=&date=19880524&DB=&locale=en_EP


Are nuclear bombers themselves damaged after dropping bombs?

Mostly, no.

The number one factor protecting the aircraft from the effects of the explosion is distance. The aircraft is traveling at a sufficient speed to be very, very far away from the bomb before it detonates. All effects of the explosion can be multiplied by the fraction: 1 / r, where r is the distance between the bomb and the bomber at donation (because circumference is directly proportional to radius). While the effects may be great at the target, they spread out as the circle grows.

Detailed Analysis:

As you emphasize the speed of light of radiation from nuclear reactions, I would like to write something about radiation and how it could influence the aircraft.

Radioactivity

Nuclear radiation consists of gamma rays, which are some sort of EM waves and particles like helium nuclei (alpha), electrons (beta) and neutrons (without Greek letter...). There is also some more stuff like positrons, protons or heavier fragments of the nuclei, but they behave similarly.

The particles indeed escape with a large fraction of the speed of light, but this has nothing to do with the nuke. They will escape with the same speed from a nuclear reactor or from tiny probes in a lab. The nuke just spills more particles than the probe, but does not give them more speed.

Alpha & beta radiation

You may know you can stop alpha particles by a piece of paper and beta particles by a 3mm sheet of aluminium. In air (ground, room temperature), alpha particles can travel not more than 10cm, and electrons not more than 10m. The exact range depends on the energy of the particles, but these are the maximum ranges for nuclear reactions. Also, the distances depend on the density of the air, so they travel farther in hot air / at high altitude.
In general, there is a high electric field inside atoms, and the charged particles.

Finally, these two particle types will never reach the aircraft throwing the bomb. Even if they could, they would be stuck in the hull and not do any damage.

Neutrons

While alphas and electrons are absorbed on a short range because their charge interacts with the strong fields inside the atoms they are traveling through, neutrons are neutral (really!), which makes them very special. They like to travel through heavy materials like lead, but are easily stopped by plastic or water (one reason for that large swimming pools in nuclear power plants, though swimming usually is prohibited). The reason is that neutrons are like ping pong balls, and lead atoms like basketballs. The basketball will not notice when it's hit by the ping pong ball, while the ping pong ball flies ahead with the same velocity, but different direction. The next hit(s) with other basketballs may put the ping pong ball into its original direction, still with the same speed.
Hydrogen on the other side is a atom as light as the neutron, hence it's like resting ping pong balls. When hit by the neutron, a hydrogen atom is punched back and absorbs a large fraction of the neutrons energy, causing it to slow down. If the hydrogen atom is bound in a molecule, it may be separated from it during this process. That's why plastic is a good shielding material, but nitrogen and oxygen in the air are already too heavy atoms, so air is a bad shielding material.

The metal the aircraft is made of is (nearly) not affected by neutrons. Unfortunately, almost every molecule of the human body contains hydrogen, especially the DNA. While the pilots do not suffer imminent injuries from radiation, this may increase the chance to get cancer.

However, Paul Tibbets, pilot of the Enola Gay (Hiroshima bomb) died in the age of 92.

One fact: "Neutron bombs" are nukes optimized to release a gigantic amount of neutrons. When ignited at high altitude, it kills all animals and humans, leaving the infrastructure (and almost all plants) intact. It's good that they are proscribed by all nations.

Gamma radiation

Coming to gamma radiation. People are most afraid of it, as it penetrates anything, and you know, the Hulk was created by it. Its nature is that all the photons it's made of have a tiny chance to interact with the atoms they are passing by. A few photons are stopped, the rest go ahead. This is why each centimeter of material reduces the intensity by a certain factor, but you will never shield gamma range completely (mathematically). Typical gamma rays need some 10cm of aluminium to reduce the intensity to 50%, or less than 10cm of lead. So, it will pass the aircraft's hull and also the pilots. Again, it will not influence the aircraft. And because it only reacts here and there with matter, there is a high chance the pilot's body will repair the damages, and the pilot will not turn green.

Other effects

Shock wave

As said in the other answers, the explosion causes a big shock wave which will definitely shatter and possibly damage the aircraft. Wikipedia says about the Tsar bomb that it was released from about 10km altitude and detonated at 4km. Using a parachute, the bomb was slowed down allowing the aircraft to travel 45km after release. Yet, the aircraft fell about 1km when it was overtaken by the shock wave.

Edit: The shock wave travels at the speed of sound, so the faster the aircraft, the farther away it is when it's overtaken by the shock wave, and the lower the intensity is. (And there are supersonic aircrafts... However, the Tsar shock wave traveled around the earth three times)

Heat

A nuclear bomb releases a lot of heat. It is said that in Hiroshima, trees 10km away from the explosion caught fire. But the aircraft was farther away and its hull is not only well cooled, but also much less inflammable than a dry tree in the summer. Nevertheless, the "Tsar-bomber" was painted with a special heat-reflecting paint according to the Wikipedia article.

EMP

Each nuclear bomb also releases a electromagnetic pulse, which can damage wide electric circuits like power grids as well as any semiconductors. However, the hull of an aircraft already provides some protection against this, and the protection can be improved more to make the aircraft EMP-hard. While today's bombers should be immune to EMP due to these protections, I guess the ones which actually have thrown a nuke were immune as they didn't use any semiconductors.

Summary

It turns out that radioactivity is not an issue because not all parts have the range to reach the aircraft, and those which do, have no influence on the aircraft.

The highest thread comes from the shock wave, which definitely damage the aircraft or at least bring it into an odd situation. I don't know what an issue heat is, but the Tsar bomber had some heat reflective painting, and an aircraft usually has a good cooling by its environment. EMP is not an issue as military aircrafts are usually already protected against them.

Remarks

Of course, radiation damage / effects depend on the time something was exposed to radiation as well as the intensity. So, when I wrote gamma rays will not harm the pilot that much, this already includes a larger distance and thus lower intensity. Near the detonation, the gamma radiation alone would kill you.

Being exposed to radiation does not automatically make an object radioactive itself. Gamma rays do not make anything radioactive, they ionize atoms and may destroy molecules. The particles may be captured by atoms forming new isotopes / elements. This isotopes / elements may be stable, or may not. If not, that atom is radioactive. However, for most materials, this induced radioactivity has a short decay time.

As said, alpha particles are not an issue as shielding against them is easy, they even can not penetrate the skin. Harmless? Body cells are most vulnerable to radiation damage during their separation, and your guts are covered with mucous membrane, where this happens very frequently. Swallow a piece of alpha emitting material, and getting cancer is more likely than just possible.

You see, radiation is a vast topic, and what I wrote about aircrafts and pilots may be correct for them, but not in general. Their main protection is: Distance is the best shielding, the farther away, the better.

Hmmm, this answer got a bit longish... sorry for that.


What is the correct phraseology for changing the runway of a landing clearance?

The phraseology was slightly incorrect, this is from the FAA's ATC Orders (section 3-10-5):

  3−10−5. LANDING CLEARANCE
  a. When issuing a clearance to land, first state the runway number followed by the landing clearance. If
  the landing runway is changed, controllers must preface the landing
  clearance with “Change to runway.”
  PHRASEOLOGY−
  RUNWAY (number) CLEARED TO LAND.
  Or
  CHANGE TO RUNWAY (number) CLEARED TO LAND

That means the ATC instruction should have been:

  American 2293 Heavy, change to runway 28L, cleared to land

All the correct information was in the transmission you quoted, it was just given slightly out of order. But that could easily be an issue for a pilot who's in a high-workload phase of flight and it's probably exactly why the ATC orders say that the words "change to runway" must come first.

I've had ATC change my landing clearance a couple of times but the controller always asked me first if I could do it:

  Tower: N12345, cleared to land 21L
  N12345: Cleared to land 21L, N12345
  [A few seconds later...]
  Tower: N12345, are you able to switch to 21R?
  N12345: Affirm, we can do that, N12345
  Tower: N12345, change to runway 21R, cleared to
  land

However, landing a C182 at a class D is a bit different from landing a heavy at SFO; I assume the controllers there have less time to talk so they may simply have changed the clearance and expected the pilot to say "unable" if necessary.


Why do some Canadian Class E airspaces have no ATC frequency on VFR maps?

In class E airspace, ATC service is provided to IFR flights, but not to VFR flights. The "NO CONTACT" note most likely refers to VFR flights, since you are looking at a chart designed for VFR flight planning. The airspace is class E, and not G, because whoever designed it wanted IFR flights to be controlled within in.

See this related answer for a brief description of the different airspace classes.


How much fuel does an airliner consume during passenger boarding?

This depends on the aircraft and airport and how they are equipped. The time varies as it takes between 30 and 120 minutes to turn around an aircraft. So ill provide GPH numbers that can be used as desired.

Some airports have umbilicals that can provide ground power. This is often fed via a cable that feeds out of the terminal. This is usually fed from what ever power supply is feeding the airport.

Some airplanes (many these days) have an APU (auxiliary power unit). These are capable of feeding the power demands during a turn around. The also make it far safer for the ground crew by not having the engines running when there is crew on the ground working around them. The fuel burn of an APU can be found in the answer to this question.

Some airports supply power through the use of a ground power unit. These can be diesel powered or run on Jet-A and their output varies. They even have them for the small GA aircraft I fly to charge the battery if it dies on the ramp. This article lists a burn of 5 gallons an hour for a GPU although sizes vary. This maker lists their GPU's by Gallon per kilowatt hour which may be more appropriate for matching load demands.


The V-22 rotor disks are much lighter than a helicopter's. There's little energy available to use to cushion a landing, so although autorotation is theoretically possible, there's little point.

The Boeing V-22 handbook has this to say (see page 26):

  The V-22 is a tiltrotor and does not rely on autorotation for  a
  survivable power-out landing. The wide separation of the  engines and
  the ability to drive both rotors with one engine  make a power-out
  landing extremely unlikely. However, if  required, the V-22 can glide
  for a predictable run-on landing in  airplane mode, much like a
  turboprop

I've seen glide ratios of 2:1 and 4.5:1 quoted on the Internet, so it'll come down quite hard and destroy the rotors.

However, the design mitigates against this in various ways, or so the manufacturer claims. In the survivability section of the same handbook they say

  V-22 crashworthiness is a function of design. Heavy components,  such
  as the engines and transmissions, are located away from  the cabin and
  cockpit area. The proprotors are designed to fray or  “broomstraw”
  rather than splinter on impact with the ground. The  energy-absorbing
  landing gear system is designed to attenuate  most of the energy for
  hard landings up to 24 fps. The wing is  constructed to fail outboard
  of the wing/fuselage attachment in a  manner that absorbs kinetic
  energy and ensures the cabin area will  not be crushed, thereby
  protecting the occupants. An anti-plow  bulkhead prevents the nose
  from digging in on impact, and the  fuselage provides a reinforced
  shell that is designed to maintain 85%  of its volume during a crash.
  Aircrew and embarked troops receive  additional protection from
  crashworthy seats that stroke vertically to  absorb energy.


how does recovering a plane from stall lead to exceeding the critical mach speed?

There are two types of stall: One is when speed drops below minimum speed, the lift curve slope flattens or inverses, flow separates and lift drops below weight. This is explained here.

The second type is a high speed stall and is caused by shock-induced flow separation when the aircraft approaches Mach 1. In this case, the aircraft will accelerate to a higher flight Mach number where its maximum lift coefficient is smaller and causes lift to drop below weight. Here stall is caused by a speed increase, hence the name.

Lift coefficient variation over Mach number (picture source)

In the coffin corner, the highest point in the envelope of subsonic high performance aircraft, both speeds coincide. Now the aircraft can fly only at one speed, both a speed decrease and a speed increase will cause stall. When the plane recovers from a low speed stall while flying near the coffin corner, it needs to speed up and consequently runs the risk of accelerating beyond the critical Mach speed at which the lift coefficient drops and causes a high speed stall. Recovery is only possible by sinking into higher density and warmer air where the difference between both stall speeds widens and more lift can be created.

Generally, this happens to jets with straight or moderately swept wings which are powerful enough to fly high and fast but are not designed to exceed Mach 1. The Lockheed U-2 would be a prime example.


How much water pressure can flight recorders withstand?

How deep can black boxes go under water?

They are required to be able to withstand a depth of 20,000 feet (3.8 miles, 6.1 km) for 30 days.

& how much pressure can they withstand?

At 20,000 feet deep the pressure is 8900 pounds per square inch (psi) which is 606 times atmospheric pressure at sea level (nearly 4½ tons on each square inch of surface)

A flight data recorder from AF447, around 13,000 feet deep for almost 2 years. Still readable

References

The DFDR must be watertight to a depth of 20,000 feet in sea water, and survive at this depth for 30 days
The units also have to withstand a static crushing force at all of its six axis points of an applied load force of 5,000lbs for 5 minutes on each axis.

See: What happens to the transponder, FDR and CVR in case of an explosion?

The southern corridor of the Indian Ocean, where officials now believe the plane went down, ranges in depth from 3,770 feet to 23,000 feet.  At its greatest depth, that’s almost equal to the height of Mount Everest (which measures 29,029 feet tall).

See: Indian Ocean depth proves great challenge for MH370 search crews

For every 33 feet (10.06 meters) you go down, the pressure increases by 14.5 psi (1 bar).

See also

List of unrecovered flight recorders


It's impossible to give a correct AND simple explanation I think. I would explain it like this if I was asked:

The downwash from the wings and the downward component of the wingtip vortices create a higher than normal pressure area below the wings because the air hits the ground and can't "escape", increasing lift.

Induced drag is reduced because wingtip vortices (causing drag) can't fully develop close to the ground.


How do airlines (or the government) retrieve information from the black box of an aircraft?

They send it to the manufacturer (or other lab) who knows how to get the data out.

Old black boxes stored the data on tape which they take out put in a reader and print out the data. Partially damaged tape can still be read, the result will be a data stream with holes in it.

Newer black boxes use solid state storage (like one of those 8gig memory cards). It will be put in a reader to read it out. The exact format of the data will be specific per manufacturer.

Then the analysts will make nice graphs of it for the investigators.


If I do PPL ground school online, do I have to do all of it?

You need at least 40 hours of ground school, according to the Transport Canada regulations (421.26). So you will need some sort of evidence to show that you have done so.

I do hope that you weren't seriously considering doing this. Please read the answers to this question.

You will see a common theme - most accidents are caused by the pilots themselves. Knowing aviation theory inside and out is the best protection you have against joining them in those statistics. It is not a stretch to say that your life depends on the attitude you bring to your flight - starting from the first lesson of ground school.


What is the most commonly occurring fault with this type of electrically driven gyro?

Some idiot using magnetized a read by flux valve.
Gears  slipping. Sync knob sticking in.
Leaving it in DG mode.so it drifts

Not correcting for Magnetic Variation changes unless you fly along an isogonal


Why do uncontained engine failures still occur?

One of the absolute requirements of an aircraft turbine engine (usually some sort of turbofan or turboprop) installation is that, in the event of a destructive failure of the engine, the engine cowling must be able to contain any and all fragments released in the process.

No, there is not. The requirement is that the engine cowling must be able to contain fragments released in case of a single blade failure.

If just a blade fails, it will often break more downstream, but as long as it is just blades breaking loose, the casing should be able to stop them and generally does.

However if the disk that holds the blades itself breaks, the energy is much higher and the cowling can't stop that. It is not really possible to make it strong enough to contain this as it would be too heavy for flight, so it is not a requirement.

All¹ the recent cases of uncontained engine failures were that the whole disk broke and left the engine in several large pieces.

¹ The Southwest flight 1380, B737 near Philadelphia on Apr 17th 2018 is a kind of exception. It was only a blade failure, but it was also initially contained. The blade that failed was actually stopped by the cowling. However then a secondary failure of the inlet cowling itself, well ahead of the fan, occurred and that was what caused the further damage and injury.


Is it possible to have a fully electric airliner?

Well, to use the same airframe, you'd basically have to find a way to replace the fuel volume in the wings with battery volume, and batteries are somewhere around 15-20% of the power density of fuel, as the answers in this ASE post lay out pretty well.

So if you had an electric fan that made the required thrust, and somehow figured out how to replace all the fuel tanks with batteries, you'd probably have something, but only with about an hour's endurance, which wouldn't even make up the IFR reserve range requirements most of the time.  You would have to replace a lot of pax with batteries to get even a couple hours endurance, which would kind of kill the business case.

So that kind of concept is pretty much a dead end until battery power density starts to approach the level of kerosene, maybe 20 or 30 years from now unless some massive new development comes along.


I found your quoted text in Section 5-4-6 of the AIM. You quote paragraphs b and c of the section. I will break down paragraphs a, b, and c using examples. Each paragraph is discussing a situation in which a pilot has been cleared to a holding fix (perhaps by clearance delivery, i.e. the last fix in the flight plan) and has been "cleared ... approach" prior to reaching that fix.
Paragraph 5-4-6 a

An aircraft which has been cleared to a holding fix and subsequently “cleared . . . approach” has not received new routing. Even though clearance for the approach may have been issued prior to the aircraft reaching the holding fix, ATC would expect the pilot to proceed via the holding fix (his/her last assigned route), and the feeder route associated with that fix (if a feeder route is published on the approach chart) to the initial approach fix (IAF) to commence the approach.

Summary: What to do when there is a feeder route from the holding fix to the IAF.
For example, prior to departure, a pilot calls clearance delivery and receives clearance to KMOB via V198 BROOKLEY VOR. They plan to shoot the ILS 15. Here is the approach plate and the chart.

Notice the feeder route from BROOKLEY to the IAF. If the pilot is "cleared ... approach" while on V198 transiting to BROOKLEY, their route has not changed. They must proceed to BROOKLEY as cleared, and then use the feeder from BROOKLEY to CAYAT (IAF). They may not turn directly to CAYAT unless specifically cleared to do so.

Paragraph 5-4-6 b

If a feeder route to an IAF begins at a fix located along the route of flight prior to reaching the holding fix, and clearance for an approach is issued, a pilot should commence the approach via the published feeder route; i.e., the aircraft would not be expected to overfly the feeder route and return to it. The pilot is expected to commence the approach in a similar manner at the IAF, if the IAF for the procedure is located along the route of flight to the holding fix.

Discusses: What to do when there is a feeder route from a fix on the route of flight prior to the holding fix.
In this example, a pilot plans to fly northbound to KMGM. They call clearance delivery and receive clearance to KMGM via V222 MONTGOMERY VOR. They plan to shoot the ILS 10.

Notice there is a feeder route from ALOON. If the pilot is on V222 heading north toward ALOON when they receive clearance for the approach, they will be expected to use the feeder from ALOON instead of overflying ALOON and proceeding all the way to MONTGOMERY VORTAC. In this case there is a feeder route from the holding fix as well, but that may not always be the case.

Paragraph 5-4-6 c

If a route of flight directly to the initial approach fix is desired, it should be so stated by the controller with phraseology to include the words “direct . . .,” “proceed direct” or a similar phrase which the pilot can interpret without question. When uncertain of the clearance, immediately query ATC as to what route of flight is desired.

Summary: If a pilot would like to fly directly to an IAF without using a feeder route, they can request to do so. The clearance must contain the specified phraseology.


How do visiting foreign pilots access Duats or Duat?

I've just arrived back home after being in the US for some months. I was required to have a FAA class 3 medical, because I did some flight training there, and luckily the one I've received is also is a student pilot certificate with the number on it you require to register for DUAT. Some of my colleges didn't have this number and so they were not able to register until getting there FAA pilot certificate. This will be send to your home adress, most probably when you are home again. In the US you'll only get a temporary certificate (peace of paper). The only number you'll find on it is your current license number.

Now what you can try: One of my colleges simply wrote an e-mail to duats helpdesk where he described his situation, giving all the information they require on their registration page with his foreign license number and attached a photography of his license and a proof that he'll be in the us for the next months. Less than 24 hours later he had a log-in. We had a student Visa, but if you don't have something like this, just try it without it, or take a photography of something else looking trustworthy.

Good luck and enjoy your trip!

Edit: I was just looking for the e-mail address, but for any reason my browser refuses to load duats website. As far as I remember, you'll find it at the registration page. If someonewho can access the website likes to add the e-mail adress please feel free to do so, I would appreciate your help.


How to calculate Night Flight time for a given flight?

This answer will address your question according to US FAA guidelines. Make sure to verify with your country’s aviation agency.
Civil Twlight
The time that you can log as “night” is based on the start or end of “civil twilight.” Civil twilight is defined as the time when the geometric center of the Sun’s disk is at most 6 degrees below the horizon. Civil twilight, as a general rule, is usually the 30 minutes before sunrise or after sunset. However, that can vary quite a bit with your location on the Earth’s surface.
Logged Time
Before (morning) or after (evening) civil twilight and between the two is when you can log night flight. You can take your total time (ie 2.3 Hobbs) and subtract any time that would not count as night and the result is what you are legally allowed to log as night time (at least here in the US).
Application for Development
I understand you're problem as a developer - you will have to use a website like timeanddate.com to grab an API that can find a local civil twlight using a city as an input. You will have to write a function that takes the departure time and determines whether it counts as night time, and then subtract any flight time that is ineligible.
I hope this addressed the mathematical request of your question and let me know if I can clarify at all.


What resources can direct me to real estate with landing strips?

There seem to be many, however, some of those "landing strips already in place" will no doubt be public airports that border the property or shared private community strips that aren't generally inviting the public.

aviationacres.com
aviationhomes.com
hangarnetwork.com
airportairparkhomes.com


Why does the Pratt & Whitney 747 have an extra engine on the right side but not left side?

It's an engine testbed aircraft. In this particular picture, the tested engine is probably one of the PW1X00G series (mainly used by Airbus A220, Airbus A320neo, Embraer E-Jets E2, Irkut MC-21, Mitsubishi SpaceJet) and the aircraft is one of two Boeing 747SP testbed aircraft owned by PW.

Engine testbed aircraft test the engines in-flight, with parameters and conditions that can not be tested in a static test on the ground (for example, low temperatures and non-static thrust).

Engine testbed aircraft often end up in unusual configurations. Other examples include (but not limited to):

General Electrics Boeing 747 testbeds: 1 2
Honeywell's Boeing 757 testbed: many pictures with different engines, even turboprops.


How can I determine the quality of training provided by a CFI at a local flying club?

Jeff, I really appreciate that you ask for safety before asking for the price. Unfortunately it takes some experience and time at a school to say if the equipment and teaching methods are safe or not, but I'll try my best to provide you with some of my insights into flight training.

I personally tend to the bigger flight schools. Having a strict training concept and standardized methods is a huge benefit in safety. If the same teachers also do more advanced training like IR or MEP your PPL training will most probably also be more intense. Your training should concentrate on learning to fly not flying the nicest routes but of course you should also enjoy your time. That's why you should of course also have a look at the people who are there. They should not only be friendly, but also be professional and well organised. The most annoying thing during flight training is bad organization and the changing of schedules due to absolutely avoidable reasons.

Good maintenance is key for safety. Here again, a big flight school that can do it's own maintenance has a lot of advantages. Often it happens that there are minor problems which should be fixed before the next flight without being a big safety hazard. It's better to squawk this and wait ten minutes until maintenance has fixed it, rather then flying without having it fixed, or cancelling the lesson. If the flight school has its own maintenance and they are happy with their work they will tell you and also show you around. Honestly the only thing you can do is to look if the hangar looks clean and tidy. If you decide for a smaller school without its own maintenance, it should at least be done at the same airport. Otherwise this could cause regular delays in your training.

Also think of yourself. During your solos and later when having your license you are allowed to and you will fly alone without an instructor. Be motivated to learn more than you have to. Know your aircraft and ask your questions. RTFM should not be the general answer of your flight school but you should spend some time doing it.

I made a list with all my questions before visiting different flight school so I don't forget to ask them. I would sugest you to do the same before getting there. If you for example ask for some more detailed information how many flight time you have to do with an instructor before flying solo and what exercises and maybe progress checks you'll have to do prior to it, you'll get a good insight how structured the flight training is. Also don't forget to ask about the theoretical part. That's really dependent on your self if you prefer to learn with books or with a teacher in front of you.


What plane is shown here in the movie Rampage?

Northrup Grumman B2 Spirit stealth bomber.


Are cabin dividers used to "hide" the flex of the airplane?

Was my fellow passenger right?

No.

That photo is taken in a B777-300 (2 aisles, 4 seats in the centre and three at the sides, lavatories only behind the central rows, rows on the left side of the aircraft are one more than the central ones at that location):

As you can see the wall is just were an emergency exit is, and if you will look on the other side of the wall you will find a "jump seat", i.e. a foldable seat used by the crew, and the wall is there for it.

Also, walls help in dividing the aircraft in different classes.


How long have commercial aircraft been continuously in the sky?

This is a great question and I will try to answer as I think it was intended. Based on reasonable assumptions, I can estimate that at least one commercial passenger flight has been in the air somewhere in the world continuously since the early 1930s.

A key help in answering the question is that passenger aviation grew very rapidly throughout the mid-20th century. Moreover, the chance probability of having zero flights in the air at some moment is mathematically very sensitive to the overall rate of flights. Thus, the historical window in which an "empty sky" is plausible would close quickly. Past some point, the overwhelming growth makes it virtually impossible that the skies would ever be devoid of commercial flights again, unless some event stopped them in sync almost everywhere in the world.

What about World War II?

In North America, despite the diversion of a significant fraction of people and resources to the war effort, many commercial passenger flights continued. Schedules in the early 1940s showed numerous routes operating at all hours of the day and night. So much growth had occurred in the 1930s that even the dent from the war left the industry well ahead. (This may well have also occurred in Australia, another developed region mostly spared the direct violence of the war domestically.)

What about 9/11?

Although US and Canadian airspace was closed after the attacks, flights continued within the rest of the world -- again making a dent but not undoing decades of growth.

So why the early 1930s?

Due to the aforementioned rapid growth, we will be pretty close if we merely get the orders of magnitude right. Assume a typical flight length of 2 hours or 200 miles in this era. Also assume that flights were uniformly distributed over a time period (say a year) -- equally likely to be scheduled at any time 24/7/365. Even within one region, flights operated day and night, and superimposing the various global time zones (even just North America and Europe) further homogenizes the flight schedules.

If we can estimate the average number M of commercial flights in the air at any moment, we can model the fluctuations statistically as a Poisson distribution. According to the Poisson distribution, the probability of finding zero flights at a given moment is e^(-M), where e ~ 2.7. This result is fairly robust; for example, if we take a different model where there are 2*M planes in the global airline fleet, each of which is flying half the time (thus M are in the air on average), then the chance that no plane is flying at a given moment is (1/2)^(2*M) = 4^(-M). The key result is that the probability decreases exponentially with M.

Roughly every 2 hours, the flights "turn over" (current flights have landed and a new set has taken off), giving us a new sample from the probability distribution. During a year, we get about 4,000 samples, and the probability that we see zero flights at least once is roughly 4,000 * e^(-M). Of course, M is increasing from one year to the next as the industry grows. We conclude that once M surpasses about 15, the probability of ever again having the sky globally devoid of commercial flights is negligible.

In the year 1930, there was already a noticeable passenger airline industry in the US (at least 6,000 passengers flown, which is likely very low because another source says over 300,000) and in Europe (10,000 in Italy, 18,000 in the Netherlands, not to mention the UK, France, and Germany).

If we estimate a worldwide total of >100,000 passengers for the year, and consider that a typical ticket was for several flight segments, say 1,000 miles, then we get >100 million passenger-miles in 1930. As further confirmation, the US alone is quoted at 84 million passenger-miles that year.

The planes were very small and load factors were low, so the typical number of passengers on board was likely around 3. Thus, passenger flights worldwide traveled at least tens of millions of miles in 1930 (compare 37 million revenue miles for US airlines, which may however include some cargo flights without passengers).

At an effective speed of 100 miles per hour, the total flight time was at least hundreds of thousands of hours. With the year containing about 9,000 hours, the sought average number M of planes in the air at once would be dozens. By the statistical reasoning given previously, this is the point at which the "empty sky" probability becomes negligible. And if we are off by say a factor of 2 in estimating M (e.g., due to seasonal variations), this corresponds to just a few years of growth.


Why can’t the F28 be deiced with one or both engines running?

The Fokker F28 can be de-iced with engines running, but this was not permitted by the Air Ontario manuals.

The Wikipedia article does not list a source for their claim:

  the Fokker F28 aircraft is never supposed to be de-iced while the engines are running because of a risk of toxic fumes entering the cabin of the aircraft

One can however find all details in the final report, which shows an excerpt from a memorandum distributed by Air Ontario's director of maintenance:

This memorandum was not known to all Air Ontario pilots:

  The body of evidence on this point does not support a conclusive
  finding, one way or the other, as to whether Captain Morwood and/or
  First Officer Mills received the Fokker cold-weather operation publication
  or the Mauracher memorandum, which contained, among other
  important information, the crucial proviso, "NEVER: Spray while main
  aircraft engine's are running!!!" (Exhibit 317, p.3). What is clear is that
  a specific pilot bulletin was never disseminated on this point, and there
  is strong doubt, based on the above-mentioned evidence of Air Ontario
  pilots, as to whether pilots Morwood and Mills had received the Fokker
  cold-weather operation publication.

  Air Ontario pilots Hansen, Wilcox, Stoger, and Monty Allan testified
  that they were not aware of specific restrictions against spraying the F-28
  for the purpose of de-icing while one engine was running. Only Captain
  Maybury, who had received the Fokker publications, was aware of such
  restrictions. In the absence of specific instruction or a company policy on
  this point, Air Ontario pilots who were questioned in this regard (in
  particular, pilots Hansen, Wilcox, and Allan) testified that they considered
  the practice of de-icing with a main engine running unsafe,
  because of the risk of ingesting glycol into the engine and the danger of
  having a person in a de-icing bucket in close proximity to a running
  engine. However, the evidence of experts in the fields of aircraft ground
  de-icing, aircraft engines, and cold-weather operations indicated that
  aircraft ground de-icing is routinely performed in Europe and the United
  States with engines running. Clearly, an operational matter of such
  importance requires a standard company policy that is made explicitly
  known to all pilots and operational personnel.

(final report, p. 658f., emphasis mine)

This implies that de-icing with engines running is possible, but without
proper guidance or procedures most Air Ontario pilots would advise against
it. The report summarizes its finding on this matter:

The report does not say however, why the original Fokker publication prohibits
de-icing with engines running.


What are these crevices below the wing of B-52 bomber?

I think that this crevice which you have noticed is the hinge line for its aileron. This might not actually be an aileron hinge line, as later model B-52s don't actually have ailerons - if this is a later model B-52, then this may just be the remnants of what the ailerons once were.
My answer is based upon this diagram of a B-52D.


What are the advantages and disadvantages of having a single castor wheel as compared to 2 wheels in an airship?

Two wheels side-by-side would only be needed if the craft is in danger of tipping over sideways. Airships should stay upright because the lifting gas will still provide most of the lift, and the wheel is only for carrying the remaining load. It can swivel for ground maneuvering when the airship needs to swing into the wind while mooring at the mast, but will neither absorb big landing loads nor carry the craft at high speed, so it can be kept small.

On the lower tailfin you should only provide a bumper for unintended ground contact; adding a second wheel would only make sense when the ship touches the ground with both wheels when level. This would be a bad design, however, because maneuvering will be much easier when the lower tail fin provides enough ground clearance to allow pitch angles of approx. 3° - 5°. Note that the lower fin on most Zeppelins was smaller than the upper fin; only the last, less slender ones could afford equally sized fins. In that case, however, you need sufficient propulsion power to keep the cruise speed well above the reversal speed.


When did the Tu95 first use its armament in combat?

Last year (!), at least per Wikipedia:

  On 17 November 2015, Tu-95s had their combat debut, being employed for the first time in long range airstrikes as part of the Russian military intervention in the Syrian Civil War.

This seems to have been using the Tu-95 as a missile platform:

  The aircraft launched a total of 34 airborne cruise missiles destroying 13 key targets...


What happens when two different control inputs are commanded in an aircraft with two control columns?

It depends on the aircraft. In any aircraft where the two control columns are linked, there's only one input to command the control surfaces. While most smaller aircraft are connected directly through the control surfaces, Boeing publicizes that on the 787 - a fly-by-wire aircraft - the control columns "[a]re cross-linked between pilots to reduce potential confusion."

On Airbus aircraft (and probably others), the controls are not linked: there is no indication on one pilot's controls of the other's position. The computer handles this by adding the two inputs: opposite commands will cancel each other out, while both pilots commanding the same input will increase the total commanded input. Some Airbus aircraft have a feature which makes an announcement of "DUAL INPUT" when there is input on both sidesticks simultaneously. As of January 30, 1997, this was "an installation" (optional feature, I believe) on the A320 and under development for the A340.

Airbus aircraft also have a Priority Takeover button, which lets one pilot take control and have the airplane ignore inputs from the other sidestick. As Farhan noted, good CRM (Crew Resource Management) is also very important to ensure that only one command is given at once.

Some aircraft have linked controls, which can be separated if necessary. On the 767, if sufficient force is applied, the elevators will "split": each control column will control one of the elevators. The pilot who is stronger or better prepared will have more control over the aircraft. There's also the EMB-145 and -135:

  The roll input is ... linked at the control column[.] Each yoke independently controls its own aileron -- the CA yoke only flies the left aileron and the FO yoke the right aileron. It is only through the control column linkage that each yoke can control the whole airplane. It is done this way so that if there is a problem with a cable jamming, the control interlock can be disconnected and at least half control regained.


What is the stall AoA for the space shuttle?

As far as I can tell, NASA has never given a straight-forward answer to this question. The theoretical stall AoA is likely in the 33-40° range (see reason for that guess below). However, at operational airspeeds, the orbiter becomes aerodynamically unstable at a lower angle of attack than the stall angle. Therefore, the stall angle never mattered for shuttle operations.

Just to be clear, this answer is only referring to the very late phases of shuttle flight (TAEM and approach and landing). The 40° of early entry might be beyond the wings' stall angle, but it doesn't really matter since dynamic pressure is low and the shuttle is on more of a ballistic trajectory.

What does NASA say?

From an old NASA answer to this question:

  The question: "What is the Space Shuttle stall speed?" is a bit of a
  trick question because, as a delta wing aircraft, the Orbiter does not
  have a clearly defined stall point.

  ...

  We have determined the minimum flyable speed based on the longitudinal
  stability characteristics.  We start by evaluating the maximum angle of
  attack, alpha, for which the Orbiter is aerodynamically stable in the
  pitch axis.  This is the angle of attack at which the pitching moment
  partial derivative with respect to alpha changes from negative (stable)
  to positive (unstable).  This angle of attack is identified as the
  maximum usable angle of attack and it varies by Mach number.

From The Aerodynamic Challenges of the Design and Development of the Space Shuttle Orbiter document:

  The low-speed longitudinal characteristics shown in figure 29 demonstrate stall-free characteristics over operating flight conditions.

The diagram on the left shows that the lift coefficient continues to increase through at least ≈25° angle of attack (meaning the stall angle must be greater than 25°). δe = elevon deflection.

The only* reference to stalling in the Shuttle Crew Operations Manual is this diagram which depicts a stall speed (not angle). The NASA answer I referenced before gives more context to this graph.

Shuttle Crew Operations Manual - Section 4.9-1

*There are a couple references to elevon stalls in the Operations Manual, but I'm not counting those.

Why does the stall angle not matter?

As we've already seen, the shuttle would exceed aerodynamic/structural limits before reaching the stall angle of attack at most airspeeds. Additionally, there are a couple other reasons for not worrying much about the stall angle.

Guidance always aimed to keep the orbiter on the "front side" of the L/D curve. This means that guidance would never command an angle of attack higher than required for "best glide". If it needed to dump energy, it would do so by deploying the speed brake and/or pitching nose down. It would never dump energy by pitching up (except during the flare). If the orbiter was low on energy, it would pitch for best glide. This means airspeed would always stay high and in the range where other factors are more limiting than the stall angle. Pitch-up maneuvers would be limited by dynamic pressure and Nz (normal acceleration — g's).

The only time the shuttle fell into the "back side" of the L/D curve was during the flare and landing. Incidentally, touchdown speed appears to be roughly the speed where the orbiter is finally slow enough that it might actually stall before becoming unstable for other reasons (see "VA" in the graph above - this is "maneuvering speed", just like in airplanes). However, at touchdown, the limiting angle is the tailscrape angle (15°), which is much lower than the stall angle.

Shuttle Crew Operations Manual - Section 7.4-17

What's the real answer?

Although not operationally significant, I think the specific question you're trying to ask is: what AoA produces the maximum lift coefficient? Generally speaking, that's considered the stall angle for most airfoils, since increasing AoA beyond that point results in decreased lift.

While I don't have a lift coefficient graph for the shuttle which goes beyond 25°, this paper discusses the results from studies on various delta and double-delta wing designs.

None of the studied designs have the shuttle's exact 81/45 sweep angles. However, given that they all have a maximum lift coefficient somewhere in the 33-40° AoA range, I suspect the shuttle was similar. I can't prove that unless someone finds the appropriate data. I'm certainly not an expert on delta wings, so my interpretation could also be wrong.


Where can I find references that directly relate drag coefficient increases to passenger capacity reductions?

The book "Airplane Design Part I: Preliminary Sizing of Airplanes" by Jan Roskam covers this extensively.

Nothing tabulated, mind you but the text goes into extensive detail of the equations involved for the sizing of a prospective aircraft and the relationships between the aircraft range, drag polars under various flight conditions and payload weights.

It also gives the equations for calculating the sensitivity of the change of aircraft range with drag polar and payload weight, which is essentially what your passenger is.

EDIT

Relevant section is in chapter 2 from page 74 onwards.Problem 1 on page 85 is practically custom tailored for your needs here.

Bear in mind there is no one size fits all application of a rule of thumb for this question as every aircraft will differ on account of any number of factors.


What is the difference between ICAO Annexes and Documents?

An Annex to the Chicago Convention on International Civil Aviation (which established the ICAO) is adopted by the ICAO Council according to particular voting procedures laid out in Article 90 of the Convention, and is binding upon the signatory States.

An ICAO document is just something the ICAO organization has chosen to publish in its Doc Series with an identifying number for ease of reference. Being an "ICAO Document" doesn't in itself say anything about who wrote it or its legal force. For example, Doc 7300 is the Chicago Convention itself, which has a lot of force (but not because it has a Doc number), whereas Doc 9562, Airport Economics Manual is more informative in nature and tries to be persuasive rather than authoritative.


Why does an airliner fuselage have a constant section over its length rather than a tear drop shape?

On the other hand, fuselage on an airliner is most of time bullet shaped.

No, it is not. A “bullet shape” has a flat end, which is where most of the drag is generated (at subsonic speeds). But that shape is never used on flying vehicles except on rockets where the end is occupied by the rocket engines.

Instead, airliners always have a tapered “boat” tail, sloping gently enough to avoid separation (sometimes with help of strakes). The resulting shape is as if you split a droplet in the widest point and insert a piece of cylinder. And the difference in drag coefficient between pure droplet and droplet with cylinder section inserted is very small.

Still, a continuously varying shape is slightly better than the cylindrical section. And the early aircraft did have that. Likely the last one of those was the Lockheed Constellation. The shape was great aerodynamically, but it was expensive to build, it made it more difficult to ensure all elements have proper strength to withstand the pressurisation, every time they derived a larger version they had to redesign all frames and in operation it was not exactly convenient for loading either.

In contrast the tubular section is much easier to design, easier to make and when they want to make a bigger version of the plane, they just insert a couple more frames and mount stronger engines to match the increased weight—between A318 to A321 or between all variants of B737-MAX, vast majority of parts is the same and there is just different number of frames and different engines. And it's simple to load—seats are mounted on straight rails and containers simply slide in to the cargo bay. And the difference in drag is small enough that the cheaper manufacturing and practicality will easily offset the increase in consumption.


What kind of malfunction is an "artificial horizon"?

Best bet is that there was an issue with the artificial horizon. If it was on an older aircraft without a glass cockpit, the gyro or its gimbal was probably broken causing the face to 'float' around or just stick at an odd angle. Then it was then communicated poorly to you by someone. Other than that I have never heard of a "floating horizon" and a google search doesn't yield any results either.


Under what conditions does the FWC give the PITCH PITCH aural call-out on the A320?

The "PITCH, PITCH" synthetic voice is called out when

  "The aircraft pitch attitude is becoming excessive during flare an
  landing."

This is an optional feature which airlines can install to avoid tail strike.

Source: ECAM Description, Indicating/Recording Systems, Aircraft Systems, A320 FCOM


Is this the shortest route served by an Airbus A320?

This site seems to indicate that they had the shortest route using the A-320 family of aircraft at just over 70km. The page also shows a list of flights, and it looks like one of them is listed at 58km. Based on that list, it looks like your 231km flight wouldn't even break the top 10.

Its difficult to search based on the length of the route and the aircraft type. As far as I can find though, 58km ACE->FUE shortest scheduled route for the A-320.


TCAS is part of a defense in depth strategy to reduce air accidents. ATC does not cover all areas, so TCAS adds protection where ATC coverage is missing. ATC is not infallible: humans can make errors and computers can go down. With TCAS pilots can get life-saving warnings even in zero visibility, without reliance on any ground based system.


If a pilot has the wrong altimeter setting, will his transponder mode C altitude be off too?

No your altimeter setting has no effect.

The altitude signal for mode C comes from a separate pressure altitude sensing "blind" encoder that only supplies the transponder, or an equivalent device integrated into the transponder itself, or a pressure altitude signal coming from an Air Data Computer on a larger aircraft.  It reports pressure altitude to a resolution of 100 ft.  So as you are climbing between 1000 and 1100 ft, ATC's indication will roll over from 1000 to 1100 at somewhere around 1050ft, from 1100 to 1200 somewhere around 1150 ft, etc.

So if you make the wrong altimeter setting and level at a cleared altitude and the pressure altitude reported by your transponder is off by more than 1 or 200 feet from the pressure altitude they expect to see, ATC will inquire about your altimeter setting.


Could the Aurora D8 have Ramjets instead of traditional jet engines?

The Aurora D8 doesn't have traditional jet engines at all. The design incorporates a very large bypass fan which due to its size is not mechanically linked to the engine core. It's more like a turbo-prop engine, but driving a ducted fan instead of a propeller. The fan is specifically designed to cope with the flow disturbance in the boundary layer. Indeed, according to the Wikipedia article

  Clustering the engines together atop the wide tail of a flattened fuselage enables them to reenergize the slow-moving boundary layer over the fuselage

Take a look at that article. It might answer a few more of your questions.


How are pilots alerted to the publication of a NOTAM affecting their flight while in-flight?

In the case of the 777 (or any flight operating on an IFR flight plan) it is ATC's (and the pilot's) responsibility to vector the flight around restricted airspace. In the event of pop-up NOTAM's, ATC will do their best to inform you, especially on an IFR flight plan. The key is you should be talking to somebody, or at least listening in. I have a feeling though that you want a little more...

Flight Information Services (FIS-B) provides weather, text, graphical weather, NOTAMs, ATIS and other information to aircraft in flight over the UAT link. ADS-B (ADS-B Out mandated for all aircraft in controlled airspace by 2020 in the US) will be able to provide similar data to aircraft in flight all the way down to small GA (if they have ADS-B In capabilities, or ADS-B receivers like Stratus).

So the crew of your hypothetical 777 will be notified multiple ways:

ATC will notify them about the need to vector around restricted airspace.
ATC will notify them about the closure of an entire destination airport as filed
NOTAMs will pop up on the FIS-B display in the cockpit
The ATIS or automated information broadcast will be updated to include NOTAM'd airport or runways
Crew will see the FIS-B display when they check destination airport weather/closures enroute
At the very least, ATC will notify the flight on approach ("Airport is currently closed, please continue to the filed alternate" or something like that)

Now, on the flip side let's say that you are a J-3 Cub with no radio humming around to your local uncontrolled field. The field was just closed due to a water buffalo migration and NOTAM'd out of service until the beasts can be removed from the property. You are on a 5 mile final and all the water buffalo are hiding in the woods next to the runway...

If you land you've violated the NOTAM and airport closure. This may warrant a call to your FSDO but you will probably be able to explain that the NOTAM wasn't active or identified prior to departure and they'll let you off (and the next thing you should do is go buy a handheld radio). At the very least you should make a report in the Aviation Safety Reporting System (ASRS) in case somebody raises concerns.

Either way if possible the FAA recommends a 4 hour minimum notification time for closures that can be planned. Why 4 hours? Most GA aircraft have about a 4 hour endurance and most domestic flights are less than 4 hours long. Obviously not everything can be planned, but ATC will work with aircraft in flight to disseminate the information as required.


What does the phrase "electrically controlled and pneumatically operated" mean?

It means that an electrical switching signal is used to drive the pneumatic or air valves in the air conditioning system.

Think about it like this: We want to use our garden hose to push open a cat flap but we want electricity to control the pressure in the hose. We could apply an electrical signal to a motor which opens the tap and lets water come out. This water pressure could then be used to control how wide the cat flap opens. The only difference in your airbus situation is that it isn't water (which would be hydraulics), it's air that comes out of the tap (Pneumatic means air). So this system would be called an electrically controlled, hydraulically operated system. Substitute the water in the hose for compressed air and you have your answer.

The way electrically operated valves work is generally based on the principles of electromagnetic force by utilising  some sort of coil. This setup turns a piece of wire into an electromagnet, which is attached to or interacts with the movable part of the valve. This then ports air pressure to one side or the other, to balance open the valve to a set amount in proportion to the original electrical signal.

So we use electricity >>> this changes the balance of air >>> the air opens or closes the valve.

The valve can be fully open, fully closed or anywhere in between.


How to calculate service ceiling and absolute ceiling in PA-44 Seminole?

You can use the given chart to define (single engine) ceilings. There should be separate graph for both engines running case.

Note: it is important to understand that the definition absolute ceiling is absolute: zero climb rate while service ceiling is defined by local regulations.

In Europe, in commercial operations for class B aircraft (which Seminole is) service ceiling is the altitude where both engines running aircraft is able to climb at 300 ft/min at present gross weight and local OAT. A single engine service ceiling is defined as "positive gradient" so it is the first usable altitude below single engine absolute ceiling.

To define required altitude enter the graph from the right from the desired vertical speed, go upwards until you meet your current (or estimated) gross weight. From there draw a horizontal line all the way across the left side of the graph. The point where to local OAT (at an altitude) and your horizontal lines cross is the ceiling according to the selected climb requirement.

When interpolating between the altitude lines make sure to go perpendicular between altitude lines - not up and down along the grid.


It's a boost reference line which carries supercharged (Upper Deck) air to the injector for mixture atomization. Naturally aspirated engines don't need this as there is no positive pressure differential between intake manifold and the ambient atmosphere.


Why is the IATA Airline Accounting Code abbreviated as PAX?

It is called PAX because this is the accounting code for passenger operations. IATA has two kinds of these codes called Accounting Code for passenger operations and Prefix Code for cargo operations.

Accounting or Prefix codes
Airline accounting codes and airline prefixes are essential for the identification of passenger and cargo traffic documents, processing of passenger accounting transactions, cargo transactions and other commercial/traffic purposes.

(iata.org)
An airline can have both codes if they are operating both passenger and cargo flights, as seen in the following list of requirements to obtain such codes:

For a 3 Numeric Accounting Code (Passenger Operations)

Valid Air Operating Certificate (AOC).
Certificate of incorporation / Company Registration, with shareholders name.
Confirmation issued by the data aggregator (i.e. OAG, Innovata)

(only if a scheduled airline)

One of the following criteria must be meet;

Passenger Bilateral Interline Agreement with an IATA code holding airline
Confirmation from BSP (IATA Billing and Settlement Plan)/ARC (Airline Reporting Corporation)

For a 3 Numeric Airline Prefix Code (Cargo Operations)

Valid Air Operating Certificate (AOC).
Certificate of incorporation / Company Registration, with shareholder names.
Satisfy requirements to publish schedules in airline guide publications (only if a scheduled airline)
One of the following criteria must be met;

Cargo Bilateral Interline Agreement with an IATA code holding airline.
Confirmation from CASS (IATA Cargo Accounts Settlement System)
Letter of confirmation from a Freight Forwarder that will be issuing AWBs on your behalf

If applying for both codes, both requirements for each code will need to be met.

(portal.iata.org)
In your example, Cathay Pacific has both an Accounting Code and a Prefix Code of 160 because they operate both passenger and cargo flights.


What does "maximum update interval" mean for Mode S GICB registers?

If you update the register, the values will be set to the values provided.
From that moment, a timer starts running. When the timer reaches 2 * maxUpdateInterval, the register will be set to all zero.

If a radar extracts the register before the 2 * maxUpdateInterval is reached, it will get the values provided at the update. If it will extract the register after 2 * maxUpdateInterval is reached, it will get all zeros in the reply.

For ADS-B, transmission of the register is inhibited (IIRC) when the register is set to all zeros.


Is it possible to land a plane only with the Garmin® Synthetic Vision?

Apparently yes, according to this 2008 review of the system in a Diamond DA40:

  With [a safety pilot], I stayed under
  the hood for the entire flight—takeoff, en route, approach and
  landing—using the system’s visual cues. I managed to land the airplane
  without breaking anything, barely. It wasn’t pretty, but it
  demonstrated what was possible.


Generally speaking the Flight Management Computer supports holding patterns. The pilot inputs the holding fix (usually a NDB/VOR), the direction of the hold (Left/Right), the inbound course, and the time/distance that one holding leg shall take to execute. These information can be found on aeronautical charts, as IFR holding patterns are published for each airport. As far as I know pilots are also trained to fly holding patterns manually, but you can understand that flying the pattern manually is not as precise as flying the pattern via the autopilot.


What is the advantage of the blisk design in the new Trent XWB engine?

Since the blades and rotor disc are a single piece, there are no additional fittings (bolts, screws etc) to attach the blades reducing complexity and weight.  The blade root joints are also a source of failure through manufacturing defects and fatigue cracks.

The disadvantage is that any damage to a blade requires the entire assembly to be replaced rather than a single blade.


Why do pilots typically start out in piston-engined aircraft, rather than jets or turboprops?

In a word, money.  Have you priced time in a turboprop or light jet, vs time in a C152 or other piston trainer?  Or actually buying one?  You can pick up a decent used single for about the cost of a new car, while turboprop or jet is likely to start at half a million, and go up from there.  And add maintenance costs to that.

Then there are a lot of pilots (I'm one) whose flying just doesn't include what a jet or turboprop is likely to be good at.  I like to fly into short strips, often grass or dirt (and sometimes no strip at all e.g. dry lake beds).  Is your jet or turboprop well suited for that?

Even for someone looking towards a career with the airlines, you can build a lot of the necessary time a lot cheaper in a single-engined prop plane.  For instance, one of my flight instructors started doing that, getting paid plus lots of experience dealing with the mistakes of student pilots.  Then he moved to a job flying a small cargo plane doing pickups for FedEx or someone like that, before getting enough hours to look at an airline job.


What is the feasibility of fitting all aircraft with black boxes?

It would be very difficult to mandate new equipment into older aircraft. Look how much it took to mandate ADS-b. Mandating it into new or future built aircraft would be easier. We may try to incorporate the telemetry-like data we are getting now into some type of solution. Companies like Sentry and Stratus could design a portable unit that records all AHRS, GPS, traffic, cabin pressure altitude, and carbon monoxide presence data for less than $1000. Combine that with a personal electronic device like a tablet or smartphone and a patch cable or Bluetooth connector, and you have most of the capabilities of an FDR/CVR combo. It would not record the position of flight and engine controls, or engine performance data, however.

The use of this may be easier to mandate. $1000 is fairly reasonable in aviation economics.

Making it mandatory for ALL passenger and property carrying commercial flights may be more feasible and likely. The federal government would implement it under the auspices of protection of the consumer or for the good of the public.


Does "the co-pilot" have any meaning?

Yes, Merriam-Webster says:

  co- prefix

  :having a usually lesser share in duty or responsibility: alternate: deputy • copilot

and

  copilot

  :a qualified pilot who assists or relieves the pilot but is not in command

while dictionary.com says:

  variant of com- before a vowel, h, and gn: coadjutor; cohabit; cognate. The prefix co-, now productively forms new words from bases beginning with any sound ( co-conspirator; co-manage; coseismic), sometimes with the derived sense “auxiliary, subsidiary” ( coenzyme; copilot), and, in mathematics and astronomy, with the sense “complement” ( codeclination).

Both sources mention / hint at the co-pilot not being the highest in the command hierarchy.

Is co-pilot ever a rank?

Yes, the co-pilot is the second-in-command (SIC), right after the captain (even if the co-pilot has more hours than the captain—it does happen). If the captain ate the fish, the co-pilot becomes pilot-in-command (PIC).

Does the term appear in aviation regulations?

It's very rare (nowadays at least), usually second-in-command will be used. Here's a mention of co-pilot in an FAA advisory circular (not a regulation per se).

  The Mentor Pilot. A mentor pilot is a professional aviator acting as a coach, co-pilot,
  teacher, and role model, sharing experience and expertise in the complex environments in which
  the EA500 will operate.

Is it used in crew management policies?

Not really. The terms used are pilot-not-flying (PNF) or pilot monitoring (PM), and pilot flying (PF). Because the captain and co-pilot can be either, they usually swap roles. The captain can be the PF on the out-bound leg, and PM on the return flight, for example. But the captain remains the PIC even when the co-pilot is the PF.

Is there indeed any standardised or formal use of it within the industry?

Popularity varies by location / culture / era. First officer (F/O) is also a valid alternative. Searching for jobs on Google, copilot returns ~9 million results, while F/O returns 30 million.

Using Google's Ngram Viewer could be skewed due to the F/O's usage in maritime environments.

What does ICAO say? (My addition.)

It's not bothered really:

  What is a multi-crew aeroplane?

  It is an aeroplane that requires a flight crew of at least two pilots. One of them is the pilot-in-command (the captain) and the other is the co-pilot (or first officer).

Related:

What are common airline crew titles and positions?
When does a flight require a copilot?
What are the roles of the co-pilot in commercial aviation?
Can two captains fly an airliner?
What is a Second Officer?


How can I log simulated instrument time and approaches in a single-place aircraft?

Unfortunately, the only way for you to get simulated instrument time will be to rent a dual-control aircraft, or to use an approved simulator. Since you can do back-to-back approaches in a simulator, you may be able to find one that charges almost as little as the equivalent amount of fuel in your Long EZ. Especially since you can forego, startup, run-up, taxi, takeoff, landing, and shutdown.
The alternative to the above is to plan on dropping everything whenever you have a suitable IFR day, and go flying. Surely, there are a couple of IFR days in which the weather is not too severe every six months.
If you can deal with the fact that your flight time will not be within your control, you could partner with another aircraft owner of a two pilot place aircraft. That pilot will need a safety pilot as well. Then, you can just alternate who is under the hood.
Another, less convenient and effective, but more productive option is to schedule and budget a regular flight and ground lesson with a CFII once a year. If you make this a recurring lesson with the same career instructor, you can coordinate with them to make this a combination IPC/BFR. This and the random IFR day you may get in a years time should keep you current. It also has the additional advantage of possibly learning something new or relearning something forgotten.
All of the above options address the issue of staying current. None of them address the issue of staying proficient in your aircraft with your avionics. For this I suggest making half of our VMC approaches as actual or practice IFR approaches. You may not get the visceral experience of being in IMC. But, it will allow you to practice your proficiency.


How far from the runway should a small plane start its descent from 5000ft?

For a comfortable decent you generally want to come down at 500 Ft/Min on the Vertical speed indicator. The 152 is doing about 95Kts over the ground (assuming no wind). So you are covering about 1.5 miles a minute to round it off. So you need to drop 5000 ft on your approach to the area. At a comfortable rate that will take about 10 minutes. In that time, covering 1.5 miles a minute, you will need to start your decent about 15 nautical miles out.


What is the maximum interception angle for ILS when on radar vectoring?

45 degrees.

8.9.3.6
Aircraft vectored for final approach should be given a heading or a series of headings calculated to close with the final approach track. The final vector shall enable the aircraft to be established in level flight on the final approach track prior to intercepting the specified or nominal glide path if an MLS, ILS or radar approach is to be made, and should provide an intercept angle with the final approach track of 45 degrees or less.

ICAO Doc 4444 (PANS-ATM)
That said, we very often use a 30 degree intercept angle, even if we are allowed to go up to 45 degrees.


Generally speaking (not specific to Airbus), what the layman refers to as "autopilot" is actually three logical systems:

The Flight Management System (FMS), which  figures out where the plane is in relation to the supplied flight plan.
The Flight Director (FD), which figures out how to navigate the plane to where the FMS wants it or according to manual inputs.
The Autopilot (AP), which manipulates the flight controls to follow the FD.

Generally, the FMS and FD will be engaged for the entire flight, but the AP is not engaged until after takeoff and is disengaged shortly before landing.

While the flight plan is issued before takeoff, it is frequently amended by ATC during flight. When this happens, the pilot just enters the new data into the FMS and lets the FD and AP adjust as needed.

However, sometimes ATC will issue "vectors" to aircraft, which is an instruction to fly a particular heading or track. To comply, the pilot dials that setting into the FD control knob and changes modes so it follows that manual input instead of the FMS. When ATC puts them back on course, the pilots simply switch the FD back to following the FMS.


What restrictions apply to flying RC and UAV planes in India at very low altitudes?

The Director General of Civil Aviation has published this public notice:

  GOVERNMENT OF INDIA OFFICE OF THE DIRECTOR GENERAL OF CIVIL AVIATION
  OPPOSITE SAFDARJUNG AIRPORT, NEW DELHI – 110 003

  PUBLIC NOTICE   File No. 05-13/2014-AED Dated: 7th October, 2014

  Subject: Use of Unmanned Aerial Vehicle (UAV)/ Unmanned Aircraft
  Systems   (UAS) for Civil Applications

  Of late, lots of interests are being shown for civil use (both
  commercial and recreational) of UAS in the country. International
  Civil Aviation Organization (ICAO) is yet to publish Standards And
  Recommended Practices (SARPs), as far as certification and operation
  of civil use of UAS is concerned.

  UAS has potential for large number of civil applications. However, its
  use besides being a safety issue, also poses security threat. The
  Airspace over cities in India has high density of manned aircraft
  traffic. Due to lack of regulation, operating procedures/ standards
  and uncertainty of the technology, UAS poses threat for air collisions
  and accidents.

  The civil operation of UAS will require approval from the Air
  Navigation Service provider, defence, Ministry of Home Affairs, and
  other concerned security agencies, besides the DGCA. DGCA is in the
  process of formulating the regulations (and globally harmonize those)
  for certification & operation for use of UAS in the Indian Civil
  Airspace. Till such regulations are issued, no non government agency,
  organization, or an individual will launch a UAS in Indian Civil
  Airspace for any purpose whatsoever. The above is for strict
  compliance.

  Director General of Civil Aviation