How are aircraft separated in a non-radar environment?

For oceanic airspace, flights proceed along specified tracks and altitudes specified in their filed flight plan. From there, once they leave radar-controlled airspace, radio reports are made to ATC, who ensure that aircraft are appropriately separated if a flight needs to change its track or altitude. See the wiki article the North Atlantic tracks, which give a good overview on the track system. Specifically:

  Prior to departure, airline flight dispatchers/flight operations officers will determine the best track based on destination, aircraft weight, aircraft type, prevailing winds and Air Traffic Control route charges. The aircraft will then contact the Oceanic Center controller before entering oceanic airspace and request the track giving the estimated time of arrival at the entry point. The Oceanic Controllers then calculate the required separation distances between aircraft and issue clearances to the pilots. It may be that the track is not available at that altitude or time so an alternate track or altitude will be assigned. Planes cannot change assigned course or altitude without permission.

and

  Contingency plans exist within the North Atlantic Track system to account for any operational issues that occur. For example, if an aircraft can no longer maintain the speed or altitude it was assigned, the aircraft can move off the track route and fly parallel to its track, but well away from other aircraft. Also, pilots on North Atlantic Tracks are required to inform air traffic control of any deviations in altitude or speed necessitated by avoiding weather, such as thunderstorms or turbulence.

I'm going to leave the "what happens when things break" to someone else.


When calculating the lift coefficient, what area is used?

Reference area for the aerodynamic coefficients (lift, drag, moment) is the planform area. Your picture shows only one wing, while the reference area S would also take into account the fuselage and the other wing: orange times twice blue and then some.

In its most generic case, the equation for wing area S is $$\int_{-b/2}^{b/2} c \cdot dy$$ with b = wing span = distance between the wing tips, c = local wing chord (orange line), y is the coordinate in direction $Y_m$.

For clarity in reference, the picture above from my old uni book by prof. Gerlach on stability & control, which shows how the definition works when sweepback and dihedral angles must be accounted for. Note how the wing/fuselage intersection is defined for the reference wing area, by extending the local leading/trailing edges of the wings.


How does the rudder on the Rutan Long-EZ work?

It's a combination.  There is a lateral yawing force that is a function of the offset between the rudder's lateral lift force when displaced, and the C of G, like any airplane.  The moment arm is quite short so it can't generate a very strong yawing moment compared to a normal tail.
However, the drag produced by the rudder, being way out on the wing tip, magnifies the yawing force as the drag force is added to the direct yawing force to get a resultant force vector which provides a stronger yawing moment than the lateral yawing force alone.
This allows a rudder surface that is smaller than a centrally located rudder would have to be, with the same longitudinal offset from the C of G, that is depending purely on lateral lift for its yawing moment (like with forward-swept flying wings with enormous central rudders a-la Marske, or if the Long-EZ had a rudder where the propeller is).
A useful side benefit of the Long-EZ's rudder configuration is due to the fact that each rudder can be displaced separately (each one is connected to one pedal, and only moves out from neutral and there is no interconnection between them); you can deflect them both outwards at the same time and use them as speed brakes.


How does keeping the parking brake applied when brake temperatures are high contribute to the dragging brake phenomenon?

From Airbus:

  Why is it not recommended to leave the parking brake ON with hot
  brakes?

  The SOP recommends to set the parking brake brake back to OFF once the
  chocks are in place when the brakes are hot (refer to FCOM for
  temperature values). This is to prevent transmitting heat to the brake
  pistons potentially causing seal degradation, hydraulic fluid
  overheating and generation of a black aggregate, that can reduce the
  piston running clearance and then lead to brake dragging.

(bolded for emphasis)


How should ground crews act to safely extinguish an airliner's brake unit fire?

Approach from upwind. The source of fire is hot brakes so apply maximum cooling, say water-based. But hydraulic fluids under pressure burn, so if brakes are engaged it's best to ensure with flight crew that the brakes are off as soon as the aircraft is stationary. Stay in the vehicle in case tyre ruptures; chances are it will go sideways. If fuel is leaking, use suitable foam.

I once saw a Harrier with a brake fire.  The burning pressurised brake fluid was acting like a flame thrower on the aircraft structure. The aircraft was written off. This happened about 1981.


What are the typical max range and max flight time (endurance) Mach numbers for the A320?

Max range, or Cost Index 0, actually has many Mach numbers depending on the weight, FL, and wind. Its range is from approximately Mach 0.57 to 0.78. Below is part of the relevant table from the FCOM (other intermediate weights are omitted):

The FCOM does not state a max endurance speed, just that in a hold, the FMS will fly the lowest of the "ICAO speed limits, the max endurance speed, or any speed constraint."

So the FMS will take care of calculating it, but like max range, it will vary.


Are there any aircraft designed to operate between an altitude of 50-80km?

Is there any aircraft designed to perform its mission into this 30km wide slice of atmosphere?

(between 50km and 80km) - apart from some experimental rocket planes and so on, I can't think of any. The main problem is there's so little air - very little opportunity to generate lift, and very little air to run a jet engine.

In theory it should be possible for a winged aircraft to fly up there (it is below the Kármán line) but the engineering difficulties would seem to make this impractical.  For more detail I'd recommend the top answer for this question: What determines the maximum altitude a plane can reach?

  What is the usefulness of this slice for aviation?

If it were possible, it would be useful for futuristic or military things like:

spy planes like the SR-71 but higher and faster
super-fast suborbital transport
passing through on getting into orbit - single stage to orbit
vehicles for example.

(All of these examples are pipe dreams at the moment of course.)


Why did LaMia flight 2933 plan a flight longer than its listed fuel range?

The investigation is still on-going so I will stick to what is factually known. An airplane's range through the air should not be confused with travel over the ground, actual distance over the ground can vary significantly depending on the winds aloft. A significant tailwind will allow an airplane to travel farther than its listed maximum range, which is really just an estimate. We won't know what happened in this case until the investigation is complete.

According to the information about the flight the pilot did not declare an emergency, so was told to orbit while another airplane which had a mechanical problem landed, this explains the loops.


Why can such a small difference in thrust make such a big difference in maximum speed?

and both are aerodynamically supersonic capable

No, not really.

The blunt nose and rather thick wing with not all that much sweep of the Hawker Hunter are not suited for supersonic flight.

The engine inlets of the Hunter lack the (movable) shock cones like the Mirage, which are needed for flight at higher Mach numbers (either a movable shock cone or a variable inlet vane are needed above around M1.6), and the shape is generally not suited for supersonic flight. Supersonic inlet needs to create an orderly pattern of shock waves inside to maintain smooth air flow and the triangular shape does not look like it would do that.

Also the Hunter engine probably has lower exhaust velocity, which makes it more efficient, but limits the maximum power at which it can still produce thrust.


How do I improve navigation with a VFR sectional chart?

The trick is not to fixate on small details, but to scan on the chart along your route for landmarks and features that combine into large geometric shapes that are easy to pick out from the air (while cruising the higher the better).

Like; highway, river, and railway line that form some shape like a large 5 mile long triangle so that there is a unique pattern, with a town at some point on the triangle that makes it especially distinctive, to the left of your track.

Note that configuration on the map.  Try to mentally compress it in your mind to allow for foreshortening because you will be initially viewing it at an angle.  Look for its match on the ground, allowing for its location to be farther left or right than expected if you've drifted off track.  As you find it and know where you are, scan ahead on the map for another easy to spot shape, as close as possible to your current position, note its distance, estimate the time to get there based on your ground speed and wait for it to appear.

Beyond that, it's mostly about establishing the correct heading to stay on track and holding it well, staying on top of your position and not allowing distractions to divert your attention too long as the world slides by below, and getting good at mentally projecting your progress based on known ground speed (like, you've been distracted for 5 minutes since your last known position, and if your ground speed is 2 miles per minute you should be between 9 and 11 miles away from it, so start looking for a recognizable geometric pattern ahead of you, say, 12 to 15 miles from last known).

A home computer flight sim like FSX or Xplane is really great for practicing this sort of thing on your own time.


How to adjust the center of gravity of an aircraft if not level when being weighed?

I drew in the approximate location of the screws used to hold a level while leveling the Cessna Cardinal for weighing.

When my plane was weighed, they had to lower the nose by deflating the nose strut some, and raise the main gear, to get the aircraft to the level position indicated by the manual, with a level across the leveling screws on the side of the fuselage. I don't know that there is a procedure to weigh it in a not-level position.


Turbulence is always a nuisance. It will require more control inputs to stay at the desired polar point, which increases drag. Also, small-scale turbulence will cause earlier transition of the boundary layer, which is important for gliders with a laminar airfoil. Powerful turbulence might even overload the airplane's structure.

Jet stream turbulence is low and only becomes noticeable at the boundaries between the fast moving air of the jet stream and calmer air above and below. To stay unpowered in the jet stream is impossible - any unpowered craft will lose altitude due to drag when moving through the air, and even a balloon will be hard to stabilize at the altitude of highest wind speed.

Even a kite is not unpowered - it needs some force acting on the line; either by an airplane flying below or by something holding the end of the line on the ground.

If you want to know what makes turbulence more bearable: Higher wing loading, lower aspect ratio and wing sweep will help. A higher wing loading means higher airspeed, so the relative speed changes from turbulence will become smaller. Both aspect ratio and sweep will reduce the lift curve slope, so changes in angle of attack will result in smaller force changes.


Where can I find this transonic prop airfoil?

The label you seek is not an airfoil, it is a research memorandum produced at Langley. (RM Lxxxx) The subject airfoil is NACA 4-(5)(08)-03 and the maximum efficiency from the test as reported in the conclusion was 88% at m0.71, partway down the curve where compressibility effects become adverse.


Special Purpose Tablet for Commercial Navigation app

I wish this site would embrace this topic because it is simply an extension of aircraft avionics and navigation.

This question will probably be closed, but I think this is an important question that doesn't have any definitive answer on the internet. I recently went through the upgrade from paper charts to electronic flight bag. There is very little guidance (information overload) or standardization on this topic. However, it is helpful to look at what some of the large aviation operators use.

Several flight schools have specific recommendations for tablets. For example,

ATP Flight School recommends the iPad mini, 32 GB, and Wi-Fi + Cellular for it's flight instructors.

Directly from ATP:

  ATP recommends the iPad mini, 32 GB, and Wi-Fi + Cellular (Available
  from Apple).

I've seen similar recommendations from other flight schools and Universities with flight programs but at the moment can't find the references (will update once I locate).

Personally, I use an iPad pro because I was informed that it has better anti-glare properties on its glass than the non-pro version of the ipad, which is important for day operations in the cockpit.

(Note, Apple lists antireflective coating on both the Pro and the Mini version of iPad but not the regular iPad).

I have run several of the Navigation apps on android and iPads and noticed that they seem to be a little better on the iPads. Some even have more features  on the iPad versus the android (i.e. WingX Pro).

Also, 32GB is more than enough (as of 2018) to run the navigation apps with all charts loaded and everything turned on including synthetic vision, assuming that it is a dedicated flight tablet and you don't have it loaded down with a bunch of other content such as videos, songs, pictures, etc. Also, you'll want to install just one navigation app, if you install multiple, and download all the charts for each one, it duplicates all the data and will use up your 32GB quickly.

I have ADS-B external antenna and it works just fine with either. The ADS-B I used creates a local wifi signal that the tablet connects to the antenna and all of the traffic and weather data is incorporated into the app. In other words, ADB-B data should work with any tablet that has wifi capabilities.


What help do you have to provide if you are seated in the emergency row and there is a situation?

When sitting at the exit you need to be the first one out of the plane. Basically when the emergency is declared and the captain says, Evacuate, Evacuate, you go to your door, check the outside for fires. Then you open the door en be the first one out of the door. You then put as much distant between you and the plane as fast as possible. Or you assist on the outside of the plane by making sure people create enough distance between themselves and the plane.

What could with hold them from sitting there is the responsibility to get the door open. Or the fact that they enter a shock and will be unable to move during an emergency.


What is "(CFMCC)" on an ILS approach chart?

A point shown in parentheses like this is called a Computer Navigation Fix (CNF). If it didn't fall right at the end of the runway, it would be marked with a small X. It's defined in the legend on page 39 (page 41 of the PDF) of the Terminal Procedure Publication User's Guide.

These points are only used to define the navigation track in the flight computer. They should not be used by ATC, but pilots could use them for reference if their FMC or GPS shows them. There is a short AOPA article about them, arguing they should be removed from the charts. Here is a much longer PDF that has a bit more detail on their purpose and a lot more detail about making sure their usage and distinction are clear.


Do USAF fighter jets go supersonic over land?

Generally speaking, FAA does not allow supersonic flights over land except in special restricted military flight corridors. These are called High Altitude Supersonic Corridor (HASSC) in the US. For example, the one near Edwards AFB is:

NASA also mentioned about supersonic flights:

  The F-18s flew in Edwards' High Altitude Supersonic Corridor at 32,000
  to 40,000 feet for the supersonic runs.

However, I read that FAA's jurisdiction is only until 60,000 feet, hence above this altitude, there are no speed limits:

  According to the FAA regulations the controlled airspace extends up to
  60,000 feet. Anything flying above may fly at “unlimited speeds.”

During 9/11 attacks, US Air Force had its aircraft fly supersonically over mainland.


Is lift/drag the same as coefficient of lift/coefficient of drag?

Yes. Lift and Drag are both obtained by multiplying the CL & CD by the same factors (1/2 rho V^2 S); the ratio L/D cancels out those factors, leaving CL/CD.


Why do the elliptical and the rectangular wing show different aerodynamic efficiency?

It turns out, elliptical lift distribution is not the most efficient planform. It is, however, the most efficient planform in terms of L/D for any given span length, and the reason has to do with its constant span induced downwash (see For the elliptical wing, what is elliptical, and why is drag regularly distributed?).

If you relax the span length requirement and instead optimize with regards to root bending moments, the Bell-Shaped Lift Distribution is actually superior to elliptical (see derivation and NASA paper). For the same root bending moment and the same lift, the bell-shaped distribution has less induced drag.


How do pilots identify the taxi path to the runway?

Source: wikimedia.org

Guiding is called progressive taxi and can be requested. A follow-me car can also be used to guide the plane. In some airports the follow-me car is mandatory, along with its fees.
In most cases the pilots use charts. Either paper or electronic. Some electronic charts offer a moving map feature, whereby the crew can see their position on the map.
Lastly, there's the new follow-the-greens (video link), in which the ATC programs the taxi route and the crew are then guided by smart green lights. Follow-the-greens cockpit video / ATC audio in Singapore Changi can be seen here.
In all cases, except for follow-the-greens, the route is given. It's worth mentioning that the taxiways are marked by signs as well.
Coming soon by 2020 (2021 update: it's now ready for deployment; full benefits by 2023) is the taxi route display for pilots, in which the cockpit displays draw the taxi route via ATC datalink. See possible interface here (Boeing). Airbus interface below:

Source: SESAR JU D-Taxi provides datalink exchange solutions for flight crew and controller during taxi, YouTube


How is the airspeed-Mach number transition handled in modern airliners?

Does the pilot flying have to manually "push the button" on the control panel?

It's automatic, with a manual changeover button available to the pilots as shown below (label no. 2).

How does the aircraft know when the transition should happen?

When the target climb indicated airspeed (IAS) equals the target climb Mach number, the changeover takes place, usually around FL260. Likewise for the descent. The target speeds are managed by the FMS and can be changed.

Image shows the FMS CDU.

  (3) Displays computed values or manually entered values for the selected mode.


Dropping an object from really high, landing at 0 velocity due to 'free' reverse thrust

What you are describing is similar to a helicopter autorotation.  That is something that does work.  The rotors both generate drag and store rotational momentum.  Then, some of the momentum is converted to lift for landing.


How is the marine perimeter of a coastal airport secured?

Often time there will be a fence installed as is the case at Maho Beach where people line up at the fence to get up and close to takeoff. The fence appears to have what looks like barbed wire on top.

If there is not enough clearance markers in the water may denote an area for boats to stay out of. Such is the case in St Barts. Aside from creating something a prop can snag these provide little security.

Assuming its a controlled airfield there is a good chance the controller in the tower can physically see the coast (with binoculars). If you floated up in any boat of size there is a good change you would simply be seen.

If you are talking about the departure end of the runway, it can also be difficult to just walk up to the back of a spooled up jet.


What airspeed is required at sea level to create the same aerodynamic pressure as cruise altitude?

You are looking for the equivalent airspeed. Here is the definition from Wikipedia:

Equivalent airspeed (EAS) is calibrated airspeed (CAS) corrected for the compressibility of air at a non-trivial Mach number. It is also the airspeed at sea level in the International Standard Atmosphere at which the dynamic pressure is the same as the dynamic pressure at the true airspeed (TAS) and altitude at which the aircraft is flying.

$$ \text{EAS} = \text{TAS} \times \sqrt{\frac{\text{density at altitude}}{\text{density at standard sea level}}} $$

At standard sea level, EAS is the same as calibrated airspeed (CAS) and true airspeed (TAS). At any other altitude, EAS may be obtained from CAS by correcting for compressibility error.


The simple answer that covers the majority of engines is that a fan has a shroud. The possible exception are unducted fans or Open Rotor Engines, which are a hybrid between a turboprop and a fan engine.
A more scientific answer is based on the difference in disk loading: How much power per disk area can be pumped into the fan for propulsion. For propellers, this is distinctively less than for fans. Some examples:

Cessna 172 with O-320 engine (150 hp) and McCauley 1C160 prop (1.9 m diameter): 39.45 kW/m².
P-51D with Packard-Merlin 1650 (1590 hp) and Hamilton-Standard prop (3.4 m diameter): 130.59 kW/m².
Lockheed C-130H Hercules with Allison T-56 engine (4590 hp) and Aeroproducts propeller (4.1 m diameter): 259.25 kW/m².

With jets, this comparison needs power when thrust is listed. Therefore, we make the heroic assumption that the speed at the fan is Mach 0.4 in static conditions and thrust is split according to bypass ratio (which is completely imprecise but will do for the purpose here):

BAe 146 with Lycoming ALF 502 (31 kN static thrust, 5.7:1 bypass ratio and 1.02 m fan diameter): 4254.35 kW/m².
Boeing 747-200 with Pratt & Whitney JT9D (213 kN static thrust, 5:1 bypass ratio and 2.34 m fan diameter): 5388.74 kW/m².
Boeing 777 with GE90 (388.8 kN thrust at take-off, 8.4:1 bypass ratio and 3.124 m fan diameter): 6077.23 kW/m².

I guess by now you see where this is heading: Turbofans are simply a different class when thrust per frontal area is concerned. And for this to be possible, three conditions must be met:

A well-designed intake which produces uniform flow over the engine face. The shroud is only the consequence of providing the fan with an intake.
A high solidity factor of the fan/propeller (the ratio of the total blade area of the propeller to the disk swept out when the prop turns)
High dynamic pressure at the engine face, so the engine power can be absorbed by the fan/propeller.

Note that those conditions depend on each other: Without the solidity, much less power could be absorbed. Without the intake, the supersonic flow at the fan tips would produce horrible losses and noise.
Now for the crazy ones. The misfits. The rebels. The troublemakers. The round pegs in the square holes:

Antonov 70 with Progress D-27 (14,000 hp and 4.5 m prop diameter): 656.4 kW/m².
MD-81 with GE36 UDF (6661 kN thrust at max climb and 3.25 m prop diameter): 803 kW/m².

Here it is hard to make a clear call whether these are fans or propellers. Their proper name "propfans" hints at that already.
A last word on terminology
Efficiency is a measure how much effort is needed for a certain result. An efficient prop needs less power per unit of thrust produced. It has few blades, turns slowly and has a big diameter. A subsonic fan would be more efficient, but would create much less thrust for a given size.
If you want to express the capacity for thrust creation at a specific diameter, use disk loading, not efficiency.


What is the bypass air in a turbofan engine actually for?

On modern turbojets the bypass air provides (at least) two things

Thrust

The air does bypass the engine core, but it is accelerated by the N1 fan and provides thrust as it is expelled rearward out of the engine.  Thrust from the bypass air can contribute more than half of the total thrust produced by the engine (upwards of 80% of the total thrust for some engines in certain phases of flight).  Part of the reason the bypass air is so efficient is that much energy is extracted from the core exhaust to spin the high and low pressure turbines (dual spool) that drive the N1 fan and the N2 compressor stages.
Engine cooling and noise reduction

Cool bypass air can be mixed with the hot air that went through the core at the rear of the engine.  This mixing cools the engine exhaust and reduces the jet engine noise resulting from the rapid expansion of that air once it leaves the engine.  The cool bypass air flowing around the engine core can also be used for general engine cooling.


Are there any helicopters with ejection seats?

Many years ago I read about the Kamov-50 helicopter family* being the first helicopters equipped with ejection seats. And Wikipedia verifies my memory:

  It is the world's first operational helicopter with a rescue ejection system, which allows the pilot to escape at all altitudes and speeds.

In the same article for the same helicopter it is mentioned that

  Before the rocket in the ejection seat deploys, the rotor blades are blown away by explosive charges in the rotor disc and the canopy is jettisoned.

Also, if you want to count experimental helicopters in, Sikorsky S-72 RSRA may be another one. Here is an interesting video, demonstrating the blades being blown away, and ejection of the pilots.

As a side note, in the article I read in an aviation magazine many years ago, it mentioned a synchronization of the seat with the blade rotation so that the seat passes between the blades. It was based on a working principle similar to the middle machine gun that some WW2 German airplanes were equipped with that fired the projectiles between the propeller blades.

Judging from the fact that I read it somewhere in the late 90s where the project was still new and developing, as PlasmaHH pointed out, that was probably more a thought rather than a fact.

* Kamov 50 and its variants/successors like Ka52


Could passengers on an airline flight create an out-of-CG situation by moving around the airplane?

I was on a flight in an SWA B737 that was mostly empty and the flight attendants moved us all toward the front. They told us it was for balance reasons.

I don't think this was a factor on flight 93. The CVR recorded the hijackers discussing what to do about the passengers. The hijacker piloting the plane asked 'Is that it? Shall we finish it off?' Another hijacker responded, 'No. Not yet. When they all come, we finish it off.' Then a few seconds later when it sounds as if the passengers are getting through the cockpit door he asks, "Is that it? I mean, shall we put it down?" The other responded, "Yes, put it in it, and pull it down." That's somewhat odd phrasing but those are translations from Arabic. It's clear that it was intentional.


Do I need to be acting PIC when doing takeoffs and landings for my 90-day currency?

The regulation does not address whether or not you have to be PIC to establish currency.  It instead states that you have to do "three takeoffs and three landings as the sole manipulator of the controls" and in the "same category, class, and type (if a type rating is required)":

  Except as provided in paragraph (e) of this section, no person may act
  as a pilot in command of an aircraft carrying passengers or of an
  aircraft certificated for more than one pilot flight crewmember unless
  that person has made at least three takeoffs and three landings within
  the preceding 90 days, and -

  (i) The person acted as the sole manipulator of the flight controls;
  and

  (ii) The required takeoffs and landings were performed in an aircraft
  of the same category, class, and type (if a type rating is required),
  and, if the aircraft to be flown is an airplane with a tailwheel, the
  takeoffs and landings must have been made to a full stop in an
  airplane with a tailwheel.


Why were the 747SP's trailing-edge flaps so much different than those of the -100/-200?

The wing was relatively too big for the airplane after cutting bits of the fuselage off, which reduced weight by 11,000 lbs. The aircraft did not require the triple slotted high lift devices anymore: if the wing area is large enough the wing requires no flaps & slats but has relatively high cruise drag. All in all the total weight savings on the SP was 45,000 lbs. (Source)

The B747SP could not do completely without flaps, but the simpler flaps of the SP saved weight. The competition at the time was DC10 and L1011, which had lower wing area and one less engine, resulting in better fuel economy.

B747SP: 300,000 kg, wing area = 511 m$^2$, wing loading = 587 kg/m$^2$
L-1011: 231,000 kg, wing area = 320 m$^2$, wing loading = 722 kg/m$^2$
DC-10 : 263,100 kg, wing area = 368 m$^2$, wing loading = 715 kg/m$^2$
Source

In cruise, a smaller wing area means less resistance: higher wing loading gives better fuel economy, but creates problems at low speed which need to be solved with high-lift devices.


What integration of aircraft propulsion would be more efficient at sea level high speed flight? A turbofan, unducted fan or a turbojet?

Penguin ancestors took to the sea for food, not to set speed records.  There is absolutely no reason to design an aircraft to cruise at sea level.  Plus you take away a very important lifesaver in the event of engine failure, the glide.  Far better to fly in thinner air, where true airspeed can be pushed all the way to your Mach limit while the indicated airspeed is far lower.

Simply apply your graphs to higher altitudes for greatest efficiency, and, unless you plan to go over 400 knots, the turboprop should be your choice, unless you find a good mechanic for your turbo-compound radial.

The weather is also a bit smoother up there too.


What educational qualifications are required to become a pilot in the UK?

There are no formal education requirements. However you must be fluent in English. The details can be found here https://www.caa.co.uk/General-aviation/Pilot-licences/EASA-requirements/PPL-SPL-BPL/Common-requirements-for-the-PPL,-SPL-and-BPL/


Which 2-seat 4th generation fighter/engine/configuration (de-militarized) would the best supersonic long-range civilian private transport?

"Best" is subjective. At the very least, you need to prioritize your criteria for the question to be fully answerable.

I'll give a short answer based on your current criteria:

Civilians can potentially buy any fighter jet, provided it's demilitarized, depending on their relationship with the government. The US certainly won't sell an F-22 or F-35 to just any individual or country, but George W. Bush might have a shot. Absolute monarchs, of which there are quite a few left, might buy a jet for their military and appropriate it to themselves.
No recent fighter jet is even remotely close to being flyable by someone with only a PPL, even with every endorsement out there. The ground is severely obstructed in these planes while landing, their stall speed is uncomfortably high, their control sensitivity out of the ballpark. The only civilian-piloted case for them would be a retired fighter pilot.
No fighter jet is capable of long-range supersonic flight. The supersonic range of all fighters is extremely short - a few hundred miles for the best-case. The only military aircraft capable of sustained supersonic flight are the B-1 and the Tu-160.
Not much weight can be removed from a fighter jet before it's easier to buy two fighter engines and build an experimental aircraft around them instead. The gun and the main radar is about it.
If one had to choose specifically a fighter jet, the best choice is perhaps the Su-34, thanks to its amenities, as well as its long range and large useful load.
Of course, with unlimited choice, the Concorde would still be the best. Out of military aircraft, the Tu-160 - it's got enough in common with a supersonic airliner to convert, and it's the largest.
If SST and bombers are out of the picture, you'll get where you're going fastest in a fast bizjet like the Global 8000. The F-18 is not suited for the job at all, as it's not even able to supercruise. A fighter jet can be fun to fly (if you can do that) for the performance, not for its usefulness as a transport.


Do raked wingtips reduce drag of a hang glider?

The main effect of the ranked wingtips is not improving the glider performance but change handling characteristics during thermaling. Such wing tip changes the stall pattern of the inboard wing during the circling in a thermal. They are optional.
Pros:

Whit this wingtip installed, you should be able to climb better in weaker thermal. Due to a change in the wing stall pattern and bigger area.
Glider should have a higher glide ratio at a lower speed. Thanks to the higher aspect ratio. See. this answer https://aviation.stackexchange.com/a/8797/54674

Cons:

Such wing tips adversely affect roll rate. Especially if you need to quickly change your bank angle in "wild thermals".

In theory, they should decrease your glide performance characteristics in high sped flight.

It is always a pilot choice. Glider looks much better with them ;)


Is there a maximum or minimum temperature for take-off and landing?

There is a maximum temp but that varies by airport altitude, runway length, aircraft and payload. You can find an answer to that question here.

There is not really a minimum temperature but it needs to be warm enough out to run the engines. Again this varies by aircraft and a preheat can usually solve this problem but there are places on earth where it be comes practically to cold to operate some aircraft. On a similar note if icing conditions prevail you are not really going anywhere but those can occur at lots of altitudes and temperatures. If the given airplane is stored outside and the airport lacks proper de-ice equipment you may be grounded.


Seating distribution in passenger aircraft

There are certain restrictions due to which the airliner didn't give you the seat even if you were ready to pay extra for it (Depends on the operations policy by the manufacturer and the aircraft).

It's mostly the weight restrictions for the flight to take-off as there might be some obstacle for the flight during take-off(hoarding on the end of runway, climate etc.). If the weight is too much then it will result in a disaster so equal weight distribution is mandatory.

Moreover in the end it's airliner which has to suffer because the seat occupancy get's affected and it has huge losses incurred by not leaving to its capacity.


Do flaps have a maximum speed limit but spoilers don't? Why?

Spoilers are used to shed energy when the aircraft is too fast or too high. That means they need to be used when the aircraft is flying fast and are designed accordingly.

On the other hand flaps are used to increase lift and when flying fast, there is plenty of lift, so there is no point in using flaps at high speed and therefore they are not designed for it.

Additionally flaps on large aircraft are more complicated mechanically. Spoilers only rotate around their forward edge, but flaps on large aircraft extend to the rear in addition to rotating downward.


Is the climb rate different for short-haul flight and long-haul flight?

Different climb performance is indeed indirectly linked to the length of the trip, but this has to do with the number of engines. All airliner's engines are sized to support flying with an engine failure right after take-off. Twin-engined aircraft enjoy slightly less stringent rules, but will basically carry twice the thrust that they need to stay aloft, so more excess power is available than in four-engined aircraft, which have only 33% excess thrust.

Generally, the best performance is achieved when running the engines at their maximum continuous thrust setting and when climbing as fast as possible. That is the reason why an A-320 or a Boeing 737 will climb faster than an Airbus A-340 or a Boeing 747. On descent, the number of engines is less relevant, so the descent speeds of all types are similar.

The link between engine numbers and range was strongest in the early jet age; now it is less clear-cut with long-range airplanes like the Boeing 777-200 LR or short-range airplanes like the BAe 146.


Does the F-4E Phantom II have a weather radar?

The F-4 radar was a low PRF pulse radar, designed to search for, acquire, and track other airborne aircraft, and then provide guidance for Aim-7 Sparrow air-to-air missiles. It also had a ground mapping capability, and a capability to detect and display severe weather, but it was primarily designed for air-to-air combat.

Later models of the F-4 had an more modern radar, (installed in the German F-4F for example) which was a high PRF pulse Doppler system, and had improved capabilities, but I don't know whether they still had a weather mapping capability. I would be surprised if they did not.


Fin and Tail formation lights.

Look up slime lights. When lit, they look like slimy green, hence the name. They are used for flying formation at night when it isn't possible to use visual clues such as wingtips, missiles, intakes, etc. Basically for dark/night visual pickup, formation keeping. They are for night operations and have visible and infrared modes (for use with NODs).


Is there a standard word or phrase in the English-speaking world to describe the angle between the fuselage and the flight path / relative wind?

It is just angle of attack.

Most anything can have an angle of attack. If you must be specific, you mention 'angle of attack of ...' Due to complexity of aerodynamics, most external elements of an airplane have their own local angle of attack. AoA sensors measure their angle of attack, and it is usually not even converted to 'wing' or 'fuselage'; it is dubbed 'indicated' or 'measured' and all limits are set with respect to that local AoA.

All these angles are usually designated as $\alpha$ (alpha), but with an appropriate index, which should always be explained in the nomenclature.

When we talk about airplane as a whole, usually the 'default' angle of attack is the one between the wind and the body frame (in the vertical plane). How body frame is defined depends on the aircraft designer, but normally X goes along the fuselage. Therefore, the angle of attack is exactly what you say: the angle between relative wind and the fuselage -- and not that of the wing (even though it is arguably more important).

Yet when we talk about aerodynamics, we may redefine the angle to mean 'angle of attack of the wing'. And even offset it to be with respect to zero lift. This is all fine as long as it's explicit. When we talk about just wing or airfoil, then the default angle of attack will be that of this object.


What aircraft is in The Do’s music video?

This looks like G-BDXJ, a modified 747 that was also featured in James Bond Casino Royale as well as other movies.

Edit: The linked wikipedia page confirms this:

  It was used as a prop in the music video of The Dø song "Despair, Hangover & Ecstasy"


What is the tallest tower (AGL) identified on a sectional chart within the Class-E-to-surface airspace surrounding an airport in the US?

Winslow-Lindbergh Airport (Arizona): Tower east of the airport is 356 feet agl.


What is the physical meaning of circulation found in Kutta condition?

Circulation of a fluid around an object by itself will produce no lift. The classic example of this is the spinning cylinder with no other airflow. Viscosity will cause the fluid near a cylinder rotating clockwise to circulate in a clockwise direction around the cylinder. If a left to right horizontal flow is introduced there will be a vector sum of the two flows. This results in the stagnation points near 8 o'clock and 4 o'clock (as opposed to the cylinder with no rotation in the left to right flow having the stagnation points at 9 and 3 o'clock.) The net result of this is the Magnus effect where lift is generated in the 12 o'clock direction.

In your first diagram (typical inviscid flow) there is no circulation. The shape of the airfoil in viscid flow causes the trailing stagnation point to move to the trailing edge (second image -- the Kutta condition). This has the same effect on the airflow as the spinning of the cylinder, in that it creates a clockwise circulation about the airfoil.

The line integral describes, for an arbitrary closed contour around the object, the dot product of the fluid flow velocity vector with the vector path moving around the contour. The simplest contour to analyze is created by following flow streamlines above and below the airfoil and connecting them before and after the airfoil with lines perpendicular to the streamlines.

Since the dot product of perpendicular vectors is 0, the integral along perpendicular portions of the contour are 0. The dot product of parallel vectors  is just the multiplication of the scalar values, and since the direction of the contour is reversed between the upper and lower streamline the effect is adding one and subtracting the other. Due to differences in lengths and the different flow speeds (Bernoulli...) along the contour, the integral is non-zero. This number represents the net effective circulation about the airfoil (total flow minus the horizontal flow.)

The interesting thing is that if you extend the contour behind the airfoil far enough to enclose the wake of the airfoil from the beginning of movement, the circulation will be zero as the circulation of total wake is the vector opposite of the circulation about the airfoil.


Why isn't a human required to confirm visually that flight controls are moving?

Same linked video @ 7:03

    [A] safety measure to forestall the possibility that the [display] shows a flight control to move when it doesn't.

The display (above) doesn't mimic the input, it shows the positions of the sensors independent of the input signal. Since the position change that is being checked is confirmed to be related to direct input, the data is valid.

In other words, an unexpected result with/without input would be an issue with a sensor and/or surface.

In lieu of digital displays, planes like the earlier 747 variants and Concorde had analog instruments that also read sensors. And with the hydraulics operating on a plane like the 737, the fact that the controls are able to move the full range unjammed, indicates that the control surfaces are responding and are also unjammed.

It gets trickier with a plane like the MD-80 where the controls move tabs instead of surfaces (a tab is a control surface on a control surface). It has resulted in an overrun in 2017. No human [visual] inspection could have detected it as the tab would have still moved as expected, but not the stuck surface, also as expected – tabs need airflow to move the surface.


Where do I find a complete Volmet frequencies list for Europe?

I have a list, you can download it here VOLMETS.I would really appreciate if you can help me confirm stations that are operational. Obviously depending on your location, receiver and antenna you will not receive all these.

The list is by no means 100% accurate and there may be stations that have ceased operations or are very sporadic in operation. Without others assisting it is impossible for me to verify each and every station.


How long is the horizontal stabilizer on a Boeing 737?

According to this Boeing pdf (page 39), the total length of the horizontal stabilizer on a 737-800 is 47 ft 1 in.


How much does pilot technique affect brake life?

I can't speak to techniques for for larger aircraft like the ones you're describing (reverse thrust, etc.), but for light GA aircraft one of the best things you can do to extend the life of your brakes is to not use them for directional or speed control during taxi1.

Most aircraft brake linings are "heat glazed" as part of their initial conditioning, and the heat from normal use (slowing down after a landing) maintains that glaze, but light brake use wears away the glaze on the surface of the brake linings, which reduces brake effectiveness and increases wear.

As far as landings go, I was always taught to use "aerodynamic braking" as much as possible (keeping the yoke back on the landing rollout). I don't know how much it helps with brake wear, but I find I don't need to be on the brakes as long, and anything that reduces the amount of time the linings and discs are rubbing on each other is probably saving a few millimeters of wear.

1 – Obviously safety is paramount here - if you're on a downhill taxiway you might have to ride your brakes unless you can get reverse thrust from your engine(s). Also on planes where differential braking is your sole means of directional control while taxiing just try not to drag the brakes the whole time you're moving.


Why did the Solar Impulse flight take so long?

No, it could not fly much faster with the available energy.

Lift is a question of wing area and dynamic pressure. Solar Impulse 2 has 269.5 m² wing area to carry its 2.3 tons of mass. This is a wing loading of just 8.53 kg/m²; much less than even gliders have (they start at around 30 kg/m²). This allows it to fly very slowly; if we assume it flies at the lift coefficient $c_L$ for optimum range for propeller aircraft
$$c_L = \sqrt{\pi \cdot AR \cdot \epsilon \cdot c_{D0}}$$
and guess the zero-lift drag coefficient $c_{D0}$ to be 0.029 and the aspect ratio $AR$ to be 19.18, the result is 1.377. This is already close to the maximum lift coefficient, which I expect to be 1.6. Now we need the lift equation to calculate the speed which is needed to keep it flying at this lift coefficient:$$v = \sqrt{\frac{2\cdot m\cdot g}{c_L\cdot S\cdot\rho}}$$
Let's assume it flies in 9000 m altitude where air density $\rho$ is only 0.4671 kg/m³, the result is 16.13 m/s or 58 km/h. Now consider that it will fly at the beginning, late at night and at the end of the flight at lower altitudes, and may not be able to fly a straight course (maybe to fly around bad weather), and the 55 km/h look entirely plausible, if not outright speedy. At sea level, the optimum range speed is only 9.96 m/s or 35.86 km/h, just about its take-off airspeed.

Flying faster would need more energy and would not allow Solar Impulse 2 to recharge its batteries for the night hours. Solar flight must be slow to be possible at all.


How are sector capacity constraints set in the current US ATC system?

I think January 25th, 2017 is close enough.
For Eurocontrol—

To evaluate sector capacities, the Network Manager uses the Air Traffic Control (ATC) Sector Capacity Analyser (CAPAN) methodology – using a fast-time computer simulation model that calculates the capacity of an ATC sector based on the controllers' workload. CAPAN is used with the Reorganised ATC Mathematical (Model) Simulator (RAMS) simulation engine.

Above quotation answers the question in a general form. The workings of CAPAN are laid out in this PDF, titled Capacity assessment and planning guidance document.

The FAA (US) isn't much different—

... the US and Europe use a comparable methodology to balance demand and capacity.

More on that here (PDF), titled 2015 Comparison of Air Traffic Management-Related Operational Performance: U.S./Europe.


What are the costs versus benefits of takeoff/landing on grass versus pavement in a light aircraft?

Pretty simple.  Even a nicely rolled grass runway is nowhere as smooth as asphalt.

Tires on grass seem to last forever, but it wears out everything else in the gear out faster.  Oleos get worked more; they get dirtier, so it's much harder on the scrapers and seals (dust (silica particles) + hydraulic fluid on the chrome = wonderful lapping compound), etc and can be expected to start to leak sooner. Scissors linkage bushings  and wheel bearings wear faster.  Fairings and bits that flex with the gear will crack sooner.  All that sort of thing.  Impossible to quantify, although tires are cheaper than oleo overhauls.

I operate from a field with grass and pavement (actually macadam - gravel/tar) side by side and I almost always use the pavement, because on smooth grass I can feel the oleos getting worked hard and they just get a lot dirtier.

On the other hand - if it's an option, I always do my engine run up on grass, and I usually start the takeoff roll (an option where I am) on the grass about 50 ft short of the threshold.  These are propeller protection measures.  Even nice clean looking pavement will have lots of, at minimum, very small pretty much invisible stones, which are murder on your propeller when stationary or when rolling at low speed/high power.

Props make great vacuum cleaners when close to the ground and pavement is like vacuuming a tile floor while grass is like vacuuming carpet without the beater attachment doohickey.


Are flights being shown as "hijacked" on airport departure screens in case they are?

Anything can be shown on a digital screen, but there is no way any airport would do that. What would be the purpose?


How does the shift in aerodynamic center affect the performance of swing wing aircraft?

With so many questions I need to structure the answer:

Effect on performance

Moving the wing backwards will also move the aerodynamic center backwards, but the high sweep of a swing wing normally means that the wing's leading edge is still subsonic even at Mach 2. This means that the aerodynamic center of the wing ist still near the quarter chord, so the shift in the center of pressure is limited to the geometric shift from sweeping the wing. Generally, a swing wing needs to be combined with a generously sized horizontal tail to have enough trim authority for all sweep angles.

The first jet capable to change sweep angle in flight, the Bell X-5, therefore shifted the wing forward when sweep was increased. Later designs used fixed pivot points, however.

If no possibility exists to trim the aircraft by shifting weight (mostly fuel), swing wings cause high trim drag when swept back. The biggest source of drag, however, is the increased structural mass for the sweep mechanism which will cause an increase in induced drag. Further, the mechanism takes up valuable volume at the center of the aircraft which now cannot be used for fuel storage. In total, the substantial improvement in wing drag due to variable sweep is almost completely eaten up by the mass increase and the trim drag increase.

A clear benefit of variable sweep is improved low speed performance: Both the reduced sweep and the increase in wing span will reduce low speed drag substantially, so a swing-wring design will show superior loiter performance. Also, take-off and landing distances are reduced because the full wing span can be used for highly effective slotted flaps.

Effect on Maneuverability

Swing wings cannot have ailerons - the high sweep angle of the trailing edge at high speed flight makes control surfaces there almost useless. Therefore, a swing wing aircraft will use differential deflection on the horizontal tail in lieu of ailerons (tailerons). At low speed this reduces the possible roll rate -- the unswept wing contributes high roll damping while the tailerons will have limited effectivity due to their small lever arm. The F-14 uses wing spoilers to improve roll rate at lower sweep angles, but spoiler control is less efficient than ailerons.

At high speed (and sweep angles) the reduced aspect ratio, the increased sweep angle and the much reduced moment of inertia around the roll axis will combine to produce a very agile aircraft.

Pivot position

The further outboard the pivot point, the smaller the shift in the center of pressure. If the wing uses a highly swept root, the pivot can be positioned outboard without loss of efficiency at high speed. Examples are the Sukhoi 17 or the Tupolev Tu-22. An outside pivot position also allows to place external loads on the inner part of the wing (wing glove) and to avoid the complexity of moveable wing stations.

The Grumman F-14 also extends a small, triangular wing extension (glove vane) at the leading edge when the wing is swept back to reduce center of pressure travel. This feature, however, was disabled later to reduce weight and complexity.

The reduced top speed demands on modern fighters mean that variable sweep will no longer be attractive to achieve an optimum design. Variable sweep vanished with the Mach 2+ requirement in the 1980s.


This is simply due to the jet stream. High altitudes fast air current flowing west to east. Therefore if you are flying against them your ground speed is reduced and it takes more time to go from London to New York than the other way around. Jet stream exist in both hemisphere but they pass through middle latitude in Europe USA and Asia wherase they mostly circle Antarctica in the south. Thus making them less important for aviation.

The jet stream is the main reason why the North Atlantic tracks are updated twice a day to ensure they are aligned at best with the winds to reduce flight time and fuel consumption.


Why are special aircraft used for the carriers in the United States Navy?

It's technical, not political

The F-35 was an attempt to do exactly what you propose, lowering costs by planned sharing of 80% of parts across variants, but it turns out that the USN's F-35C costs over twice as much as the USAF's F-35A, and only shares 20-25% of it's parts. The project has been a disaster practically since day one, and the services are already working on separate replacements tailored from the start for their very different missions.

Per Wikipedia, the USN decided a carrier variant of the F-15 would be too expensive and the YF-16 was inherently not suitable for carriers, so they modified the YF-17 into the F/A-18 by making the changes you propose. The USAF didn't need those changes, so they stuck with the faster and cheaper YF-16, which became the F-16.

Keep in mind that all US aircraft carriers combined hold the fourth largest air force in the world. That sort of volume means the USN can afford to customize planes for their exact needs, whereas other countries with far smaller carrier fleets may be forced to make do with planes that the USN considers "unsuitable" or "too expensive", especially if they aren't US allies.


Published minimums for an ASR or PAR approach.

An ASR is essentially a non-precision approach with an MDA, while a PAR is a precision approach (found almost exclusively at military fields) with minimums of 200 and 1/2.


If I fly both Part 135 and Part 91 in a 24 hr period, which regulations apply?

Part 91 contains the General Operating and Flight Rules. These rules apply to almost every civil flight within the USA.

Part 135 contains the Operating Requirements for Commuter and on-demand operations and the rules governing persons on board such aircraft.

So when you fly the "Part 91 flight", you follow the regulations of Part 91.

When you fly the "Part 135 flight", you follow the regulations of both Part 91 and Part 135. If Part 135 is more strict in some regard, the more stricter rule of 135 applies.


Is drag higher when flying in a crosswind?

No, it's not true-- have you ever seen a birds feather's blowing sideways?

We fly INSIDE of the wind, not AGAINST the wind.

You should draw the airplane symbol on the left-hand leg of the triangle, pointing in the same direction as the left-hand leg, and you should draw the "relative wind" arrow equal in magnitude and opposite in direction to the airspeed vector, i.e. the left-hand leg of the triangle.

Consider the fact that many of us have had the experience of actually BACKING UP in flight, relative to the ground.  Now, do you think the air was flowing backwards over the wings?


Where does the factor 1.3 for Vapp come from?

1.3 Vso is not a universal rule even for the same plane.  First is extra weight, which requires higher AOA for adequate lift at the same speed, or greater speed at the same AOA. Approach a little faster if heavy.  Next is CG.  If CG is near limits, a little extra speed will help aerodynamic trim as you slow down.  Finally, there is weather. Gusting winds or wind gradient (head wind dropping as you near the ground) should make the pilot consider adding a few knots to approach speed as well.

The best policy is to do what is safe for your plane.  A very slow plane that lands at 25 knots may be more like 1.5 or higher, especially on a windy day.

1.3 Vso is a fairly good approximation for a plane that stalls around 50 knots, approaching
at 65 knots.

Another consideration in approach is safely banking in the pattern.  Stall speed increases with bank angle as follows.

Load factor G = 1/(cos bank angle)
Stall Speed (Accelerated) = Vs x Square Root G

For 30 degree bank:  G = 1/.8662 = 1.155  (thought I had it here for a second!)
               Accelerated stall speed = Vs x 1.07

For 45 degree bank:  G = 1/.7071 = 1.414
               Accelerated stall speed = Vs x 1.18

For 60 degree bank:  G = 1/.5000 = 2.000
              Accelerated stall speed = Vs x 1.414

So we avoid steep turns in landing patterns as well!  Yet another reason to add safety margin
to approach speed.


In an emergency, can an airliner land at Pyongyang or another North Korean airport?

I can see at least three questions here and only one of them is fully aviation-related. First, can an airliner legally divert to Pyongyang in an emergency, under the laws of its own country? For US airlines, the answer is yes. 14 CFR 91 SFAR 79 bans flights over North Korea, but does allow an exception in an emergency:

  2. Flight Prohibition. Except as provided in paragraphs 3 and 4 of this SFAR, no person described in paragraph 1 may conduct flight
  operations through the Pyongyang FIR west of 132 degrees east
  longitude.

  [...]

  4. Emergency situations. In an emergency that requires immediate decision and action for the safety of the flight, the pilot in command
  on an aircraft may deviate from this SFAR to the extent required by
  that emergency.

Second, will North Korea allow the airliner to land? This is a political question, not an aviation one. Either they say yes or they say no. If they say no to an airliner in distress, how will they enforce that? Are they willing to shoot it down rather than let it land? Would that decision depend on the country of the airliner? Can they even make that decision within minutes, or is it already made and they simply initiate a defined procedure? The pilot is probably just going to try to land anyway; assuming the alternative is a crash, he would have little to lose.

Finally, what will the 'reception committee' on the ground look like? No idea, this is a political/military question.

But practically speaking, this situation should never arise anyway (ignoring movie plot stuff like hacked navigation systems). If your country isn't friendly or at least neutral to North Korea, your airlines simply won't plan flights where the only emergency landing possible is in Pyongyang, and for US carriers specifically it would be illegal anyway.


What is the difference between a published and unpublished TFR?

It looks like you have two questions: what's an unpublished TFR, and where are NOTAMS published?
First, unpublished TFRs. I can't find any FAA information on "unpublished TFRs" and I suspect it was just poor phrasing from FSS. I read the article you linked and it's unclear what they really meant, at least to me. Having said that, you could interpret "unpublished TFR information" in two ways:

Unpublished information about TFRs
Information about unpublished TFRs

I believe the intention was #1. There's a blanket 'stadium TFR' NOTAM but it doesn't include key information, like when the TFR is active for a given stadium. That's because games schedules change and the FAA doesn't keep track of them; it's up to the pilot to know if there's a game going on or not. For that reason, the stadium TFRs are very unpopular with pilots.
But, FSS might still tell you if a stadium TFR is active. Especially for major, high-profile events like the Super Bowl. There's no guarantee that they can or will, though, especially since FSS has become more centralized and less local.
Second, NOTAMs. The FAA currently publishes them here: https://notams.aim.faa.gov/#News
I say "currently" because the FAA seems to like moving things around and breaking links. But as you can see from that site, you can search yourself and there's also an interface that other systems can use.
Finally, that brings me to the practical answer to both your questions: just use your favorite flight planning app. I use Garmin Pilot, which displays current and future TFRs, and it keeps track of sporting event schedules. It also has NOTAMs, of course. Foreflight or other alternatives would do that too, I'm sure.
The stadium TFRs are usually easy enough to work around because - except for really big events like the Super Bowl - you can fly through them anyway if you're talking to ATC. So if you can get flight following (always a good idea) then you're complying with the TFR requirements.


How exactly am I supposed to notify ATC when I fly my drone? (UAS)

If you are flying as a hobbyist

If you are flying as a hobbyist, which seems to be the case, you are required by Public Law 112-95 FAA Modernization and Reform Act of 2012 section 336 to:

  (5) when flown within 5 miles of an airport, the operator of the aircraft provides the airport operator and the airport air traffic control tower (when an air traffic facility is located at the airport) with prior notice of the operation (model aircraft operators flying from a permanent location within 5 miles of an airport should establish a mutually-agreed upon operating procedure with the airport operator and the airport air traffic control tower (when an air traffic facility is located at the airport)).

This, of course, does not say how you are to contact the airport operator and air traffic control. The traditional way would be to find the telephone numbers for the airport and air traffic control, and to call them. Alternatively, as you discovered, some mobile phone apps allow you to electronically submit notices to some airports. What is not required or desired is to contact ATC by radio. If you are operating very near an airport, it may be a good idea to get a radio so that you can listen in.

If you are flying under Part 107

If you are flying under Part 107, you do not have to contact the airport or air traffic control even if you are within 5 miles of an airport, but you must not fly in controlled airspace without obtaining an airspace authorization or airspace waiver. These processes are, at this time, handled through the FAA Drone Zone website, and not by contacting the airport or ATC. Depending on the terms of the authorization or waiver, if granted, you may be required to contact ATC prior to operation, and they will need a way to get in touch with you.

Which rules do you need to follow?

Broadly, if you're flying for fun (e.g. as part of an enthusiast group, in your back yard, or taking personal photos in the park (although watch out for people as per the safety guidelines you are following)), you are a hobbyist, and subject to the special rule for model aircraft.

If you're flying for commercial or business purposes (e.g. taking photos of houses for real estate sales, inspecting railroad tracks, or delivering purchased packages), you need a Part 107 license and to fly under Part 107 rules.

For more information, see the FAA's sUAS FAQs and the table on page 11 of the FAA's interpretation of the Special Rule for Model Aircraft (pdf).


How do aircraft keep fuel from freezing while in flight?

Much like water, exposing fuel to below freezing temperatures does not instantly make it freeze.  It takes some amount of time, and as long as the fuel is not exposed to below freezing temperatures long enough to make it freeze, it won't be a problem.

How much time?  That depends on a number of factors like:

Type of fuel

Jet A (common in the US) has a freezing point of -40 C
Jet A1 (common outside the US) has a freezing point of -47 C
Jet B (common for some military aircraft and very cold airports) has a freezing point of -60 C

Initial fuel temperature

If you fuel in the middle east during the middle of summer, the fuel will be a lot warmer than when you fuel in Siberia in the middle of winter.  Warmer fuel will take longer to freeze.

Outside air temperature

Much like trying to freeze water to form an ice cube, the colder the air around it, the faster that it will freeze.

Aircraft speed

The faster that the airplane goes, the more friction there is as the air flows over the wing.  This heats up the air close to the wing and makes it take longer for the fuel to freeze (see previous point).  The temperature at the wing is known as TAT:
For example, at an actual temperature of -56.5 C (SAT) and Mach 0.72 the TAT is -34 C, but at Mach 0.80 the TAT is -29 C.
For more information about SAT -vs- TAT, see my answer about Air Data Computers.

Quantity of fuel

Much like a small pond will freeze before a large lake, in order to get fuel to freeze you need to lower the temperature of all of it.
The more that there is, the longer it will take.

Aircraft design

Some aircraft run hydraulic lines close to the fuel so that the heat will help slow down the freezing.
Some aircraft constantly pump fuel to keep it moving and mixing if it tends to freeze in one part of the tank before the rest
Some aircraft use fuel to cool the engine oil using a heat exchanger, and return the warmed fuel to the tanks
Many other design factors

In general, fuel will not freeze in the typical amount of time that an aircraft is aloft.  If particular routes pose a problem, there are several options that the operator and pilot have:

Use a fuel with a lower freezing point
Fly at a lower altitude where it is not as cold
Choose a route with warmer temperatures
Increase the speed of the airplane
Carry extra fuel
Transfer fuel in a way to keep fuel warmer.  Typically this is done by transferring fuel from the relatively warm fuselage tanks to the wing tanks which are exposed to more of the cold air.


Why were these crash location not located via ELT?

ELT's are not required to be built to the same standards as the CVR and FDR. That means they are much more likely to be destroyed in a severe crash. Also, ELT's (the old style 121.5 and 243 mhz and the new 406 mhz) are not designed to function under water or mud.


What makes the swooping noise when a jet flies overhead?

The effect you noticed is the result of the combination of Doppler effect and sound absorption.

Sound absorption in a fluid is proportional to

$exp(- \alpha \nu^2 x)$

where $\alpha$ is a dimensional constant, $x$ is the traveled path, and $\nu$ is the sound frequency.

In its own reference frame, the airplane emits always the same sound, irrespective of whether it is approaching or receding from the observer. But for the observer, the frequency of a wave (which is $\nu_0$ in the plane frame) seems $\nu_a = \frac{\nu_0}{(1-v_j/c_s)}$ when the airplane is approaching, and $\nu_r = \frac{\nu_0}{(1+v_j/c_s)}$ when the plane is receding (here $c_s$ is the sound speed and $v_j$ the airplane's speed). Thus the perceived frequency jumps by a factor

$F = \left(\frac{1+v_j/c_s}{1-v_j/c_s} \right)$

This means that the absorption coefficient, at the time when the airplane is passing overhead (thus $x \approx H$, the plane's height over the ground), jumps from

$D_a = \exp \left(\frac{-\alpha H \nu_0^2 }{(1-v_j/c_s)^2}\right)$

to

$D_r = \exp\left(\frac{-\alpha H \nu_0^2 }{(1+v_j/c_s)^2}\right)$

For typical values for the atmosphere, and the propagation of sound waves in it, this means that $D_a \ll 1$, while $D_r \approx 1$.

Hence, what is happening is that, as the airplane passes roughly overhead, the sound goes from being deeply absorbed, especially at high frequencies, to not being absorbed at all (its normal sound, as you call it). The strange sound you noticed is what you perceive as the lower frequencies are becoming less and less absorbed, and thus the sound spectrum changes.

EDIT 1:

after I wrote my reply, DClayton (in a comment above) gave a very important hint that this is exactly what is happening when he noticed that the same effect appears with gliders, hence it is unrelated to engine sounds (I ignored this, thanks).

EDIT 2:

it is also worthwhile remarking what happens for high-altitude planes, when observed from the ground: in that case, the traveled distance $x$ is sufficiently large that all frequencies audible to human ears are absorbed, so that the plane goes from being nearly silent when it is approaching to being very clearly noticeable as it is receding.

You may try this on a clear day with high humidity at high altitudes, when over-flying jets leave white wakes: you will be unable to hear them as they approach (even though you can see them thanks to the presence of the white wake), but you can easily hear them as they go away, but just keep in mind that all of this is delayed by the (substantial) time it takes for sound to reach the ground, which, for 33,0000 feet or more, is of order 30 seconds. In other words, you will hear the noise level grow perceptibly about 30 seconds after the jet has passed the point closest to the observer, i.e. 30 seconds after flying directly overhead.


Why is port-starboard terminology used in aviation?

It isn't (much).

Ships are the most similar thing to aircraft that existed before them, so it made sense that aviation took over many terms and conventions from seafaring (the pilot in command is called captain, the cockpit is the flight deck, distances and speeds are given in nautical miles and knots etc.)

However since there is no physical port in an aircraft to serve as reference (most aircraft have doors on both sides), everybody has to learn to give the sides relative to the direction of flight and then it does not make sense to teach them new words when they already know “left” and “right”. So “port” and “starboard” are only used where there is a naval tradition.

I know British military aviation (RAF) used it (in wartime stories and documents it is common, but according to Simon's comment it is not common any more) and the US Navy uses it with ships, but I don't know to what extent they apply it to aircraft.

However, it remains popular in simulator games, presumably because it is catchy and unusual and using jargon makes people feel special.


Has mod percent changed for Mark-1 glide slopes?

The percentage of modulation hasn’t changed, rather the way it is measured. Upon further review the current measurement is 80% SDM (sum), where before the measured value was 40% for 90 & 150 hertz individually. The method of measurement change, may be due to rare case instances where 90 and 150 shouldn’t be exactly equal, but together the sum is always 80%.


Do glider pilots have to wear parachute in countries where mandatory even if flying with a foreign glider?

For US (N-reg aircraft), this is defined in 14 CFR 91.703, Operations of civil aircraft of U.S. registry outside of the United States. It says:

  (a) Each person operating a civil aircraft of U.S. registry outside of
  the United States shall—

  (1) When over the high seas, comply with annex 2 (Rules of the Air) to
  the Convention on International Civil Aviation and with §§91.117(c),
  91.127, 91.129, and 91.131;

  (2) When within a foreign country, comply with the regulations
  relating to the flight and maneuver of aircraft there in force;

  (3) Except for §§91.117(a), 91.307(b), 91.309, 91.323, and 91.711,
  comply with this part so far as it is not inconsistent with applicable
  regulations of the foreign country where the aircraft is operated or
  annex 2 of the Convention on International Civil Aviation; [...]

That suggests that in most cases the pilot should follow the foreign (Italian) regulations:

91.703(a)(2) says you have to follow foreign regulations on "flight and maneuver"
703(a)(3) says you should (mostly) follow part 91 unless it's "inconsistent" with the foreign regulations

It all seems a bit vague to me, and what "inconsistent" means is probably the kind of thing that keeps lawyers busy. But also note that there are specific rules applying to operating foreign aircraft in the US. 14 CFR 91.711, Special rules for foreign civil aircraft, begins:

  (a) General. In addition to the other applicable regulations of this
  part, each person operating a foreign civil aircraft within the United
  States shall comply with this section.

So foreign aircraft in the US are expected to follow US regulations as far as possible, which is consistent with 91.703: an N-reg aircraft abroad follows the foreign rules as far as possible, and a foreign aircraft in the US follows US rules as far as possible.

Since both the US and Italy are ICAO members, I would expect Italian law to roughly mirror US law on this, although that may be a dangerous assumption. For an authoritative answer, I would ask both the FAA and the Italian authorities.


Did Boeing build airliners other than the 7x7 series?

Yes, Boeing built other airliners, with different numbering, although none of them were jet-powered. Three iconic designs come to my mind right away, although there were others:

The Boeing 247 predated the DC-3 into service, and was a highly advanced twin-engine, monoplane cabin design. It was a pioneering aircraft, introducing all-metal construction, a cantilever wing, and retractable landing gear. It was later surpassed by the DC-3, as the 247's cabin was too small for serious airline service.

The Boeing 314 "Clipper" was a large four-engine flying-boat transport from just before World War II. Not quite as pioneering as the 247D, it nonetheless was massive for its time and heavily influenced later large Boeing designs.

The Boeing 377 "Stratocruiser" was a post-World War II design based on the B-29 bomber, with a double-deck (double-bubble) fuselage and four piston engines. It was large, pressurized, and technologically advanced, but relatively unsuccessful in sales compared to contemporary designs like the Lockheed Constellation.

As others have mentioned, the aircraft in your question is a Sud Caravelle, which was designed to solve the same problem as the later Boeing 737: it was a shorter-range airliner meant for smaller routes. You point out how much the Caravelle's nose looks like the Boeing 787, and you're right - but it is even more similar to the De Havilland Comet; Sud licensed the design from De Havilland.

All photos from Wikipedia.


Why was the TSR-2 literally burnt down even before its first official flight?

The TSR-2 flew quite a few times (24 times); atleast the first prototype did. The mockup was burnt, not the prototype- one of them was shot to pieces for target practice, so pretty much the same fate.

The main reason cited for the cancellation was costs- the rising costs (quite common in new aircraft development), with the expected unit cost triple of original estimates led to the cancellation of the (behind schedule) aircraft by the cash strapped UK govt. The projected replacement, F-111 was also cancelled for the same reason. Note that TSR 2 was the last time the British went solo on combat aircraft development (with the exception of Harrier)- the amount of money required was simply more than what was available.
Strictly speaking, the test flights were not flawless - there were engine and landing gear problems, though these were typical in aircraft development. Though these were not insurmountable, the test flights were fairly typical of aircraft development and nothing special.
The test aircraft was not fitted with the full avionics package; so there is no way measure its performance. However, the entire system was new and would've caused issues with integration and performance (though in all fairness, there was no indication that that would be a great problem), not to mention the effect on cost.
Quite a few of the components developed for the aircraft (The engines, for example) were later used in other aircraft projects, so the program wasn't a total loss.

To a certain extent, development, manufacture and operation of new aircraft requires political will more than technical capability (which can be obtained, given enough time and money); the British govt. didn't have it.


What does "inertial" refer to in "inertial reference"?

It is called inertial, because it works by measuring—and integrating—inertial forces¹, that is forces due to acceleration of the reference frame (i.e. the aircraft). Gyroscopic effect used to measure rotation is also due to inertial forces.
The measured forces include gravity², which can't be easily separated, but this is done by observing that the speed is limited, so the average acceleration must be zero and therefore the long term average equals gravity.

¹ In general relativity the inertial forces are usually considered as real as any other, so the term “fictitious” is not really appropriate.
² In general relativity gravitational force is considered an inertial force. In standard English terminology, gravity also includes centrifugal force due to rotation of Earth.


Why does the DC-8-70 have the same MTOW as the DC-8-60, despite its more powerful engines?

But maximum takeoff weight is determined by engine power

not by engine power alone. The airframe also has to be strong enough for the intended takeoff weight. There is a structural strength margin, but this margin is mandated by the certification authority so you can't use it. The design won't have much more than the required margin because that would make the aircraft heavier than necessary and less competitive.

At a minimum, you'd have to get the aircraft certified at the new MTOW, which requires expensive testing. Worst case, you have to modify the design of parts like the wing box/spars, landing gear, and fuselage structure.

By 1988 the writing was on the wall for narrowbody 4-engined aircraft, with ETOPS-180 coming into force.

  It's the maximum weight at which the aircraft is physically capable of attaining liftoff speed on an infinitely-long frictionless runway at zero density altitude with one [for twinjets] or two engines [for more-than-twinjets] inoperative;

No. That would make the definition of MTOW useless in the real world. Compare to the FAA definition:

  The Federal Aviation Administration has defined Maximum Takeoff Weight (MTOW). The MTOW of an aircraft is the maximum weight at which the pilot of the aircraft is allowed to attempt to take off, due to structural or other limits.

The MTOW you see in manufacturer specifications is a figure established in the certification process. This will be below the physical maximum weight the aircraft can handle, to make sure there's a margin of safety.

In many circumstances (airfield runway length, altitude, temperature)

  an aircraft may not be permitted to take off at its MTOW... The maximum weight at which a takeoff may be attempted, taking into account the above factors, is called the maximum permissible takeoff weight, maximum allowed takeoff weight or regulated takeoff weight.


With today's technology, why can't we find crashed planes

Having a technology and using it are two different things. As already noted, you are able to get pictures from Pluto because your tracking station knows where it is.

Similarly, the aircraft position is determined by Primary Radar, which literally scans the sky, but its effective range is limited and they are costly to operate. The secondary Radar locates the aircraft by interrogating its transponder, which provides the ATC with its location and speed. However, if the transponder is not working, there is no way for to detect the aircraft locations.

The aircraft can also communicate with the ground station using ACARS, but it depends on on board electrical system. The same goes for the ADS-B, which depends on onboard systems for determining its location and speed.

Its a bit like trying to find your mobile after switching it off. No app is going to work.

Assuming that the aircraft is involved in a crash, the Emergency Locator Transmitter (ELT) can be used to trace the aircraft. However, these are not mandatory in scheduled flights(though ULB is mandatory).

Satellites could help, but again, they should know where to look for.

The wifi or working mobile phones onboard could help, but these are yet to be implemented in any big way.

The next generation technologies under development will allow  real time tracking of the aircraft, but these are still under development.


What missile defense systems would be used against hypersonic glide vehicles?

From an aeronautical point of view, an interceptor normally must be faster than the target it is seeking to reach. Therefore, existing missile defense systems are ineffective against hypersonic aircraft, because the target is moving at least as fast as the would-be interceptor.
Of course, if the target moves in a unchanging straight line, then it is theoretically possible for the interceptor to reach it, so long as it is positioned in front of the target. For this exact reason, all hypersonic missiles are designed to make irregular movements in any situation where an interceptor may be present.
For straight line paths, there is a cone of viability where an interceptor needs to be in order to intercept the target. The slower the interceptor is, the smaller this cone becomes. In the current (2020) strategic situation, the cone of intercept for existing hypersonic weapons is so small that the probability of intercept is impractically small, even for high value targets. This is one reason why there is a great effort currently to develop laser-based defensive systems.


Why are flaps retracted when an aircraft is parked on ground?

A few different reasons:

Good pilots put the aircraft into a well-known (up) configuration after landing, so that the aircraft is ready for use on the next flight.
Flaps down during taxi was a signal to the tower that the aircraft had been hijacked.
Take-off flaps (10 degrees on my airplane) and landing flaps (45 degrees), are nearly always different, so leaving the flaps down after landing at, say, 45, doesn't save any steps for departure. If the pilots forgets to set flaps before takeoff, some aircraft (like mine) will make it almost impossible to depart and climb out on full flaps because of the induced drag, while takeoff with no flaps is possible.
Prevent trucks and people from hitting the flaps while the airplane is parked, especially in the full-down (landing) configuration.
Some pilots employ the practice of retracting the flaps during the rollout because it puts more weight on the wheels, reducing stopping distance.
Flaps down increases the amount of lift generated by the wing, so some aircraft might actually lift off the ground while parked with full flaps in high winds.


Why did the AvroCar fail to fly above 3 feet?

From what can be gleaned from the Net, it was instability. The Avrocar had plenty of power but was unstable. The resulting behavior made it uncontrollable when leaving ground effect. In this publication I found an illustration which tries to explain what went on:

Any asymmetry in flow would shift the center of pressure, resulting in a wobbling motion called hubcapping (because it resembled the motion of a hubcap when dropped to the ground).

From the linked document:

  On September 29, the ﬁrst attempt of sustained ﬂight was made with the Avrocar pinned to the ground by cables. After that the vehicle took off, an uncontrollable oscillation occurred with each wheel alternately bouncing on the ground. […] These ﬁrst captive ﬂight[s] revealed then a new problem, called “hubcapping” which has never been fully resolved. The hubcapping was rapid and unpredictable swings in pitch and roll axes.


Would adding a fairing to landing gear to spin the tires before landing yield enough benefits?

Check out this answer to a similar question. What it boils down to is that pre spinning gear has been looked into but there are implications of spinning up that kind of mass. The rotational inertia created created by doing so effects the handling of the aircraft. On a similar note its often easier to have a simple part that wears out and needs to be replaced often (like a tire) than a complex part that needs maintenance and is more likely to be problematic.

The part you describe is pretty common on small aircraft to reduce drag over the wheels. As far as I know it does not aid in spinning the tires. Since the tires are more or less flush the air simply flows over them.

For what its worth these boots also can get in the way. If the plane lands hard the tires will balloon out and rub up agains the sides of the boot (depending on the tolerances) this may break the boot the tire or both.


How long does it take to assemble an Airbus A380?

Airplanes are not built like cars where after completion, they are showcased at dealership to attract prospective buyers. For larger commercial airplanes, airlines place an order first and then wait for the airplanes to be manufactured, custom modifications completed, inspected by the airline and then delivered. It is a bit complicated process.

However, one of the A380s Emirates ordered, was manufactured and delivered in 80 days:

  Emirates are celebrating having their fiftieth Airbus A380 in service
  with the release of footage showing how 800 workers across Europe came
  together to build the biggest passenger jet in the sky in just 80
  days.


What are the advantages of electrical systems over pneumatic systems?

Just on example: The energy taken from the engine as bleed air is contained in this bleed air as heat and as pressure. Now pipe this energy to someplace where it is needed, and the air will cool down and lose some of its pressure. Also, if you want adequate insulation and low transmission losses, the cross section for the piping will be substantial.

Compare this to taking the energy from the engine by a driveshaft turning a generator: Friction losses will be a few percent at most, energy conversion in the generator will be at above 90%, and transmission losses are low again if your cable cross section is sufficient. Note that the cables will be much thinner than any bleed air line would ever be.

Add to this the advances made in converting electrical energy between different voltages and frequencies, and it becomes clear that modern aircraft systems can be made more efficient when run electrically. The use of compressed, hot air was only a better choice when modern power electronics were not yet around.


What's the difference between SLG strut used in B777 and truck position actuator used in any other aircraft like B747?

The SLG strut (found on B773ER) is a truck position actuator on steroids.

The truck position actuator is used to bring the landing gear truck into a position suitable for stowing in the wheel well. This is true for all Boeing aircraft.

The SLG (Semi Levered Gear) strut on the B777-300ER is additionally used to increase T/O performance. During T/O the wheel truck is locked perpendicular to the strut, shifting the point of rotation from the middle of the truck to the aft wheel. Thereby the rotation pitch can be higher and the tail clearance during rotation is increased by about 30cm / 12in.

After selecting gear up it behaves like a normal truck position actuator, moving the landing gear truck into stow position before the gear is retracted. During landing it is disconnected and serves only as a shock damper.

Source:

FCOM B777-300ER
http://boeing.mediaroom.com/2003-06-18-Semi-Levered-Gear-Performs-During-Boeing-777-300ER-Flight-Tests


Are the nearby airplanes cleared of the sky when launching Falcon Heavy?

SpaceX launches from Cape Canaveral Air Force Station (CCAFS), Vandenberg Air Force Base (VAFB), and Kennedy Space Center (KSC). All three have Restricted/Warning areas overhead and out to sea, from the surface to "unlimited" (i.e. space). It is illegal to fly through active Restricted airspace without permission. Warning areas are used over international waters and thus flying through them is not illegal, but they give fair warning you may not survive the experience, so pilots treat them the same.

These areas aren't active full time, but since activation of these areas is unpredictable (most have fixed schedules), airlines never plan flights to pass through them; it's simpler to fly around them every time, even though most of the time it isn't necessary.

GA flights, though, are quite common in those areas when they're inactive; ATC will allow flying over the launch areas, landing facilities, etc. as low as 500ft. When they're active, it's not uncommon for dozens of GA planes to be circling just outside the area to get the best view of the rockets, both going up and coming back down. However, GA flights don't show up on most flight tracking web sites by default, so you may not be seeing them.


Are frisbees and boomerangs technically gliders?

No, they are airfoils. Airfoils are the contoured shape of the wings that give a boomerang the proper amount of lift as it's launched and spinning through the air. They operate on the same principle as the wings and propellers of airplanes and helicopters. You might even say that a boomerang is a combination of a wing and propeller. Frisbees operate under two main physical concepts, aerodynamic lift and gyroscopic stability. When flying through the air, a Frisbee can be viewed as a wing, with Bernoulli’s Principle governing the magnitude of the lift force which keeps it aloft.


Is there any book like the "Stick and Rudder" about the helicopter?

There's a book called "Cyclic and Collective" by Shawn Coyle. It's a good book, although it is a little bit more detailed than something like "Stick and Rudder". There's a lot of good stuff in there, though.


As said on Wikipedia, the principle says:
$$\frac{v^2}{2} + gz + \frac{p}{\rho} = \text{constant}$$
i.e., assuming no changes in the gravity potential energy or density:

an increase in velocity comes with a decrease in pressure
a decrease in velocity comes with an increase in pressure

It's all part of the same principle, there is no "reverse" needed.


What factors should be included when calculating hourly aircraft operating cost?

Unless you have a private airstrip and have no intention of insuring the craft you need to include the fixed costs as well. Generally you can do this yearly, then divide by the number of expected hours a year. Some fixed costs are

Storage (hanger or tie down)
Insurance (highly variable)
Annual (this will vary depending on whats broken but there is generally a minimum situation to expect assuming the mechanic finds nothing wrong.
Anything that has less than a 50 hour life time, if you are in this for ownership or renting you are going to fly more than 50 hours a year (I would hope) so you should budget in things like spark plugs, break pads and other high wear parts that get replaced often)

Other reserves may be

Repaint Reserve, this will vary depending on storage and use
Landing Gear Reserve this includes but is not limited to, breaks, tires, shocks, rotors, etc. Budget more if its a complex plane, less if its a Mooney...
Fluid Reserve (not oil) you may also have hydraulic fluid and break fluid.
"Toys" this is money you may chose to add on to your reserve so that you can (down the line) upgrade aging components that may not be broken. For example adding a 430 in place of a radio pair or moving to a full or partial glass cockpit.
Interior, if you are renting this plane and expect it to see heavy use you may want to set some cash aside for the interior. Don't underestimate the difference a warn seat will make vs a fresh seat.

Emergency Fund: This is not a reserve to add to as much as it is cash on hand. If you are renting this plane or even relying on it for heavy personal use you may want to have a budget for emergencies. Especially if you are renting and a down plane means lost rentals. What are you going to do if you need a new fuel tank, or you have a bird strike, or something hits the windshield and cracks it?

Odds and Ends Budget: Nuts and bolts, interior finish screws, that dinky little plastic knob, repainting your yoke, a pitot tube cover (for the 10th time because you lost all the other ones...)


It’s a high-frequency antenna, used mostly on flights traveling across seas and oceans, where there tends to be areas without VHF and UHF coverage. This was the case on older aircraft, most newer ones have a smaller hidden one on the tail-fin.


How does a full fuselage and structure inspection happen in practice ? (for modern Civil airliners)

The FAA "Class D" maintenance/inspection of commercial airliners, which must occur every 6 years, is extremely thorough:

The cabin trim is completely removed to inspect the airliner's skin and superstructure from the inside. Seats, safety equipment and control system linkages are also inspected in detail with each individual cable or wire tested.
The plane's exterior paint is removed to inspect the exterior skin, including rivets and seams.
All critical moving parts on the exterior of the plane (engines, gear, ailerons, flaps, spoilers, rudder, elevators, shock booms, etc), are removed from the plane, disassembled and visually inspected for wear or damage, then re-assembled and tested.
All pressurized lines (hydraulic, water, fuel) are removed from the plane and each part individually visually inspected before being re-assembled and pressure-tested in the plane.
The cockpit is stripped, all moving parts in the control column and throttle assemblies visually inspected, and all flight instruments visually inspected and tested.

There are many more maintenance/inspection tasks than I list, I'm just going through the major ones. The plane is more or less stripped to its bare metal frame, every component visually inspected and tested, then the aircraft is reassembled with individual systems tested again on the airframe. The process can take up to two months for each aircraft, and can cost between 5 and 7 million US dollars. Most major airlines have either their own in-house maintenance crews or the manufacturer perform this maintenance, with a team of FAA-employed inspectors overseeing and signing off on all the work.

Most airliners receive 3 Class D inspections in their lifetime; at the fourth, occurring around 24 years of airframe age, the cost of a Class D is typically not considered worth it given the aircraft's remaining value, and the aircraft is usually retired and either sold to smaller non-US airlines operating in jurisdictions with less stringent standards, mothballed and stored for potential replacement parts value to the rest of the fleet, or sold for scrap. Some airframes in service with some airlines have been kept through four Class Ds in order for the airline to have sufficient time to procure replacements; American's remaining MD-80s are largely newer airframes acquired in the TWA merger, but there are a few of American's own deliveries left in the fleet which are past 24 years and are still around mainly to allow American sufficient time to work through the bankruptcy, United merger and procurement of replacements (Boeing's 737 production lines are going full-tilt and American is not the highest-priority customer, so American had to split its order in this class between the 737 and Airbus's A319 and A321).

Because of the level of detail and deconstruction required, including complete cabin trim and paint removal, airlines often use this maintenance interval to perform any desired upgrades or tweaks to their fleet configuration. Common upgrades in recent years have included:

adding winglets for vortex reduction (reducing drag and allowing closer spacing at busy airports),
upgrading avionics and even control systems (some older airframes can be upgraded from direct cable-driven hydraulics to electro-hydraulic controls allowing partial automation of flight with EFDs),
upgrades to cabin trim including re-spacing of passenger seats (more or less legroom or "slant", balancing between class seating),
replacing galley equipment and other secondary systems that may be a different standard from the rest of the fleet,
adding new passenger conveniences (such as satellite-based Wi-Fi, headrest IFE, etc) and
new exterior paint schemes for corporate rebranding (such as American's ongoing rebadging from their decades-old AA silver to the new American white, and Southwest's recent move to the "Heart" scheme from its older "Canyon Blue" and the original red/gold before that).

Aircraft acquired in airline mergers are often the highest priority as the airline seeks to rebadge and standardize the acquired fleet to operate alongside its existing planes (and ensure no corners were cut by a struggling airline that would create liabilities going forward).


It's a Chengdu F-7. Albania only had Mig 15 and 19. Look at the shape of the vertical stabilizer, pitot and body behind the canopy.

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