Sadly, that information's pretty much impossible to give a general answer for, as it changes from batch to batch:

Refineries blend crude "to taste" as well as pricetag, so to speak, and the crude blend used as the refinery feedstock may change from batch to batch.
Process conditions in catalytic crackers and reformers can change depending on the point in the batch you're at, the incoming feedstock, and even the history of prior batches (say the last thing that ran through the cat cracker degraded the catalyst slightly...)
Jet fuels as-delivered may be a blend of multiple refinery batches and even the output of multiple refiners
Pipeline batching can also lead to subtle changes in fuel composition as it is transported -- pipeline operators try to "cut off" as much of the transmix as they can, but 100% isn't easy without wasting tons of fuel as transmix.  (Some pipeline operators will stick a "dumb pig" between high spec products, such as jet fuel, and their neighbors in the pipeline, but this is by no means universal.)

That said, you can make some determinations based off of a representative SDS for Jet-A, courtesy of ConocoPhillips:

The fuel consists of medium-weight hydrocarbons, from C9 to C16
The only specified aromatic component is napthalene, with a maximum concentration of 3%
No additives (anti-static, FSII, anti-oxidation, biocidal) are specified -- these are generally variable from batch-to-batch, depending on the specific purchaser (a large airport might get to spec these directly with the refiner, while the small GA 'dromes are at the mercy of whoever pulls up in the fuel truck)


Camber directly affects the amount of circulation an airfoil can generate, adding camber will always generate a higher zero alpha lift coefficient (intersection of the lift coefficient curve with the x=0 axis) up until a point that there is too much camber to sustain attachment.
This leads directly to the question asked - does camber increase CL_max? For any given AOA, there is an ideal suction side geometry that generates a pressure distribution that is always on the edge of separating. Liebeck defined this ideal shape but only for laminar flow, for which the boundary layer equations are closed form, this was all based on the work of Stratford who came up with the ideal pressure recovery. Having a surface that is about to seperate everywhere can even be true for a symmetrical section at some inclination, although it's not going to look like a NACA 0012/15 or anything familiar. The effect of the pressure surface on the amount of circulation generated, is much more insignificant than the suction surface, but it is not zero. Therefore, a cambered airfoil will make slightly more load at max CL than a symmetric section.
In reality, there is no magic button to increase, decrease camber. Airfoils are complex geometries that cannot be driven by one parameter without affecting everything else. Adding camber by 'bending' the airfoil somewhere near the front of the chord will give some more circulation, but also probably increase the departure angle, and create a risk of separation towards the trailing edge where the pressure recovery is too steep for the boundary layer to cope with.
Unfortunately there is no easy +camber = +max lift coefficient relationship, but for a cambered and non-cambered airfoil designed to operate on that separation limit, the cambered airfoil will generate slightly higher max lift.


On a Boeing 737, can the APU, BY ITSELF, provide enough thrust to move the plane while on the ground?

I can't reference to a document, but I can say with reasonable certainty that the answer is no, because like any turboprop or turboshaft, the APU has nearly all of the energy of its mass flow extracted for bleed air, or for torque production purposes for electricity, so that there is little thrust energy available.  Turboprops typically get maybe 10% of the total energy available from the engine as exhaust thrust.
So using that number for an APU in an airplane the size of a 737 that is making, say, 650 shaft horsepower (just an educated guess; the actual number is surprisingly hard to find), it's producing a thrust equivalent to roughly 65 hp statically out its tailpipe, which equates to perhaps 2-300 lbs of static thrust (I recall that it's something like 4lbs thrust = 1 HP in the static case) at most.  That would be if the tailpipe was even optimized for making thrust in the first place (tapered to accelerate the flow), which they are generally not.
So, figure on a few hundred pounds of push at most, probably quite a bit less, which isn't going to move a 737 unless it's on some kind of near-frictionless surface, or in outer space.


What's the technical name of the side window on Boeing and on Embraer?

The windows to the side of the pilots on the Embraer airplanes are called "Direct Vision" (DV) windows.   They are named as such because they can be opened and removed both during normal ops on the ground and emergency ops while airborne to provide forward vision when the main windscreens are obscured.


What are these vehicles with no callsign used for?

They have Mode-S transponders / ADS-B transmitters specifically for vehicles such a the ERA SQUID, Thales MOSQUITO or Saab Sensis VeeLoPDF.

Typically vehicles that operate on taxiways and runways are equipped with such transponders, which ensures the vehicles can be tracked by the Advanced Surface Movement Guidance and Control System (A-SMGCS).
Vehicles that only operate near parked aircraft are usually not equipped.

When using a magnetic mount, these transponders can be easily transferred between cars. This reduces the total number of transponders needed, but makes it necessary to reprogram the call sign after each transfer. For this reason it may have been decided to have no call sign in the transponder at all for these vehicles at Sydney airport.

An example of an airport using fixed installations with call signs is Amsterdam airport. Using FR24 you can see bird control, maintenance, supervisors, tugs, fire trucks etc. driving at the airport and sometimes,  when they forget to turn the system off, on the highway.

After some further investigation, I am fairly sure they use the Saab Sensis VeeLo in Sydney. The units are magnetically mounted to the vehicles. Each unit transmits using a fixed unique 24-bit address (like all Mode-S transponders /  ADS-B tranmitters) and no call sign. In the A-SMGCS software the 24-bit address is mapped to a call sign which is displayed on the Controller Working Position. There is procedure in place to ensure that when a vehicle is entering the manoeuvring area the correct mapping between the 24 bit address and the call sign is in the A-SMGCS system.


How do young pilots in the USA accumulate 1500-hours to become a first officer?

1 word: Instruction.

I learned to fly in the US, and all but one of the 10-15 instructors at the school were young guys who had a Commercial license and were just building hours while doing their exams and applying to airlines.

This meant they were actually getting paid (not particularly well, I hasten to add!) to build hours, rather than spending money on an airplane, or rental.

They say you don't become a pilot for the money, you do it because you love it. Nothing could be closer to the truth IMO.


How is a sideslip maintained (aerodynamically)?

(Source)

Here's a representative image of the variation in lift coefficient with respect to angle of attack.  The same airfoil is considered in a "clean" configuration, with a deflected flap, and then with both flap and slat (you can ignore the last, which is the uppermost example).  You can see that, with deflected flap (or, shall we say, rudder) the lift slope shifts upwards, changing the lifting generated at a given angle of attack since the rudder deflection has, effectively, changed the airfoil's camber.

Hence, while the airfoil's angle of attack has changed, the lift generated at that angle of attack has also changed.  Cambered airfoils can generate lift at negative angles of attack and so, for a given rudder input, the aircraft will assume a steady sideslip angle where the induced yawing moment is in equilibrium with any restoring moments generated by the rest of the airframe.  From my time flying gliders, this could be illustrated by the fact that, no matter how much rudder I put in, I could only make the aircraft yaw so far--there just simply wasn't enough aerodynamic control authority to overcome the force you mention as well as unbalanced yawing moments generated by the fuselage and wings.  But, at the same time, I could intuitively change my sideslip angle by proportionally varying the amount of rudder I put in or, to be consistent, I could modify the aircraft's equilibrium position in yaw by incrementally "changing the camber" of the vertical tail.


Can an ICAO contracting state charge money for NOTAMS?

Extract from ICAO Annexe 15 (Aeronautical Information Services):

3.5 Cost recovery

Recommendation.— The overhead cost of collecting and compiling aeronautical information/data should be included in the cost basis for airport and air navigation services charges, as appropriate, in accordance with the principles contained in ICAO’s Policies on Charges for Airports and Air Navigation Services (Doc 9082).

Note.— When costs of collection and compilation of aeronautical information/data are recovered through airports and air navigation services charges, the charge to an individual customer for the supply of a particular AIS product, either in paper or electronic form, may be based on the costs of printing paper copies or production of electronic media, and costs of distribution.

NOTAMS are issued gratis (free) as the information can be essential to the safe conduct of flights. The raw NOTAM is available to any member of the public, anywhere in the world online via the country's AIP (Aeronautiical Information Publication/Services) documents which are of a standard format. You'll probably have to register at no cost as a user though.
Click here for the FAA site
A company could charge a fee for processing the info thus obtained so as to tailor the NOTAM list and filter it in a manner suitable for a particular Operator. Or they could put it into a more user friendly format. It maybe noted that briefing areas have (computer) terminals dedicated to this linked to the official NOTAM server, and these terminals can have powerful filtering capabilities already provided by the issueing/distributing authorities.
ICAO lays down that safety related info should disseminated in such a way that there's no undue hindrance for the end user. Think of it this way - could the authority refuse this info to the pilot if it so happens that the subscription was not renewed on time due to any mundane reason?


Is there any particular reason the A380 doesn't have a centre wing tank?

It simply doesn't need one. Depending on the source, the A380 has a range from 8200 NM1 to 8477 NM2. The current longest scheduled flight is AKL-DOH, which is 7848 NM3. So the current configuration is capable of flying any of the current routes.

As far as the A380F, it really wouldn't make sense to add a center tank there either. The extra fuel weight would mean less cargo capacity available.

 1 Wikipedia

 2 Aerospace Technology, 11/19/2013

 3 Wikipedia


Has there ever been a fully automated takeoff, cruise, and landing of a large aircraft similar to commercial airliners?

The book The Glass Cage describes a fully autopilot-controlled military test flight in 1947. The plane was a C-54 Skymaster with seven men aboard. According to this source, the pilot aligned the plane on the runway for takeoff, but the takeoff, course control, and landing were performed by autopilot with no human engagement. See also this report from the Chicago Tribune at the time.


What is the most recent turbofan engine that used steel for its bypass fan blades?

The tickness of the Fan blade is not only defined by the structural requirement but rather for aerodynamic purpose, thus the geometry of the blade won't change much depending on the material used. Most of the metallic blades in use are hollow.
The price of the blade is quite irrelevent in modern engines. If you can decrease the wheight of the fan by 10% for double the price you'll do it as it will ensure so much fuel saving over the life of the engine. Thus I don't see the advantage of using steel over titanium for a fan blade.
Looking at other comments I understand it is for prototyping and needs to remain cheap. I would then recommend to build the core with 3D printed material which will give you the airfoil shape for aerodynamic and then enclose it with a metal sheets in order to obtain a sandwich like structure. This could greatly increase the stiffness and strength without much added weight.


What makes snow on the wings during take off so dangerous?

it is not obvious if it could alter the wing shape for this to be a problem

It may not be obvious but it is so.

Plain old snow will just blow off as soon as the plane picks up speed, but if the wing was above freezing when the snow first fell on it, the snow will probably conceal a layer of rough ice, which will not blow away.

Anything adhering to the wing surface will change the lift force. According to this article even a thin coating of ice can disrupt an airfoil's boundary layer airflow, causing a premature aerodynamic stall and dramatically increased functional drag.


What does Elon Musk mean by "electric jet"?

Jet noun

a rapid stream of liquid or gas forced out of a small opening

A Jet Engine is an Engine which uses a Jet for propulsion. Typically, a "rapid stream of gas", in which the gas is air. Really, we could count pretty much any aircraft engine as a jet, but it depends on how "rapid" you require the air to be before it's a jet.

In a typical jet engine as we define it now, the jet is created by burning fuel and air... but there's no requirement for that to be the case. An electric jet would simply use an electric motor to create a rapid stream of air.

Would it really be a "jet" engine? That depends how fast the air is - but most people see "jet" as being a fast, powerful, reliable type of aircraft, so it's as much about marketing as anything else. An Electric Prop or Electric Plane doesn't sound as cool as Electric Jet... (Although I'd argue that ElectroJet/ElectroProp/ElectroPlane are awesome names and Elon Musk has let himself down by not using one of those names)


Is it unprecedented for an F-16 to get hit by its own bullet(s)?

I can find no record of an F-16 shooting itself down prior to the Dutch incident. There is certainly nothing on the wikipedia page for aircraft shootdowns or anywhere else I can find.

However its not the first aircraft to manage the feat. In 1956 a US Navy F-11 Tiger became the first aircraft to shoot itself down, whilst testing its cannons on a test flight. The pilot fired a long burst of cannon fire then entered a shallow dive and hit the afterburner, shortly after the aircraft was hit by its own bullets.


How does my Casio watch know the altitude in flight?

The pressure in the cabin does not remain the same. It decreases, but much more slowly, in such a manner that when the aircraft is at 37000 feet the pressure in the cockpit is the equivalent of 7000 or 8000 feet. Keeping the cabin pressure at sea level would pose incredible stress on the fuselage, due to huge difference in pressure between the inside and the outside.


How does an airliner adjust and move exactly over the coloured lines before stopping in front of the jetways?

There are a few different ways. Probably the most low-tech and widespread is by marshaller guidance, which is a person outside the aircraft guiding the pilots by means of visual signals:

The exact hand signals to use are defined by the ICAO, meaning that they are identical no matter where in the world you are flying.
Most larger airport have some sort of "docking system" at some or all of their stands. There are different types, but they are all external systems that provide visual guidance for the pilots, just like a marshaller. The simplets form is a big mirror next to the parking position:

More common are electronic docking systems, which use various sensors to detect the exact position of the aircraft and calculate any corrections needed by the pilots. They are placed directly in front of the position where the aircraft must stop, typically mounted on the terminal building or a high mast:


Are aircraft accidents more frequent in specific countries?

Crashes, meaning accidents with significant number of fatalities, are so rare, even in places with least attention to safety, that it is not possible to conclude the risk is higher in some countries with statistics.

And if you wanted to judge from the number of incidents, that is including events that were dangerous, but ended well, you would be stopped by the fact that quality of incident reporting varies wildly. In this interview Simon Hradecky, the editor of The Aviation Herald, explains that Canadian TSB reports many, many incidents, but that is is not because the safety would be poor in Canada – quite to the contrary – but because they have particularly good system of reporting them. So many incident reports can actually be taken as a sign of good safety in that country, but you can't make any statistics from that.

Regarding the countries you mention:

Indonesia is widely believed to have poor safety. The EU Air Safety List says:

  All air carriers certified by
  the authorities with
  responsibility for regulatory
  oversight of Indonesia, with
  the exception of Garuda
  Indonesia, Airfast Indonesia,
  Ekspres Transportasi
  Antarbenua, Indonesia Air
  Asia, Citilink, Lion Air and
  Batik Air, including …

clearly indicating that EASA does not believe the aviation authority of Indonesia oversees operators registered under them sufficiently.

Together with high incidence of severe weather and a lot of mountainous terrain this creates environment where the risk might be elevated. As mentioned above, even there accidents are not that common to allow firm statistical conclusion.

The excepted airlines however proved to EASA that they have a safety management system in place and that it works according to industry best practice. With them, the risk probably isn't significantly higher than with any other decent airline.
Malaysia and Russia: I have not noticed any specific concerns about safety in those two countries. If you seem to have noticed accidents in those two countries in particular, it is likely just bad luck.


These designators are assigned, on request, by ICAO. The request is made by the applicant through their National Aviation Autority.

There are actually two designators: the ICAO three letter code and the ICAO R/T designator.
All assigned designators are published in ICAO document 8585.

Two things are to be considered:

The three letter code must be unique to the aircraft operator
The R/T designator (callsign) must not cause confusion with other operators flying in the same area,  preferably at most three syllables long and it must be pronounceable in at least one of the following languages; English, French, Spanish or Russian.

Since there are many operators that have "airline" or "airways" in their name, that word is usually avoided in the R/T designator as it easily causes confusion.

For pilots it is not too difficult, they are typically paying attention specifically to their own R/T callsign. For controllers it is more difficult since they have to associate the three letter code on their screen with R/T designators that or not related in an obvious way.

For example:

British Airways has three letter code BAW and R/T designator
"SPEEDBIRD".
Thomas Cook Airlines Ltd has three letter code TCX, and R/T
designator "KESTREL".
Thomas Cook Airlines Belgium has three letter code TCW, and R/T
designator "THOMAS COOK".
Thomson Airways has three letter code TOM, and R/T designator "TOMSON"

Since the application goes through the NAA, there are slight differences in the procedure from country to country. Some examples are listed below:

Netherlands

AIC

USA

FAA Advisory Circular AC 120-26K and
FAA Order JO 7340.2D.
NBAA call-sign application guidance website


How does one determine the freestream and ultimate slipstream velocities to estimate thrust?

The free stream velocity can be measured with a calibrated air data system. This uses a pitot tube somewhere at the front, the readings of which have been compared to known speeds in previous flights. The difference between the total pressure and the static pressure gives the dynamic pressure which can be translated into the desired speed.

The speed in the slipstream must be measured across the full cross section to ensure that the full speed profile is known so the slipstream speed used for thrust calculation really is the mean of all the speeds in the slipstream. This is done by measuring the total pressure at several locations, for example by using a moveable rake.

Combined temperature and pressure rake (picture source)


Why didn't government regulators prevent MH17 from flying the route it took?

The Airlines can decide for them selves which route to take, however the government has an intelligence operation which can predict events that might happen in political unstable regions of the world. However in the case of MH17 it was not the "army" that shot down a plane but an conflict between rebels and the government.

Routes flown to Kuala Lumpur

While the flight from Amsterdam to Kuala Lumpur from Malaysia airlines have been suspended, one can still retrieve the route flown via flightaware.com:

The KLM flightpath (KL809) 10246km:

The Malaysia Airlines flightpath (MH19) 10855km:

From the plots it can be seen that both Airlines diverted their routes after the accident with MH17. They both avoid Ukrainian airspace.

Would flying these routes prevented the accident? Yes, but at the time intelligence agencies where not aware that the Separatists had acces to such advanced surface-to-air missiles. This also because the nature of the conflict would not suggest that such weapons would be required.


May someone please suggest EHA design procedures for AFS?

This 1986 USAF experiment might help.

  The purpose of this test was to demonstrate in flight for the first time the
  feasibility of powering a primary flight control surface with an
  electromechanical actuator (EMA) in place of the standard hydromechanical
  actuation system. An advanced development model model EMA drove the left aileron
  on a specially modified C-141A aircraft and was to duplicate the functions of the
  standard hydromechanical unit. Lockheed-Georgia Co. (GeLac) was the prime
  contractor with Sundstrand Corp. as the subcontractor.

  [...]

  The C-141 aileron is statically and dynamically stable with
  the critical flutter parameters being tip weight and actuator stiffness. If
  either parameter were not present, the damping would still be sufficient within
  the aircraft normal operating envelope. Laboratory studies had shown that the
  stiffness or spring rate of the EMA was identical to the hydraulic unit. All
  else remaining unchanged, the structural damping of the modified aircraft was
  expected to be the same as that of the baseline aircraft. The baseline aircraft
  has a flutter margin more than 20% above the normal operating limitations of the
  C-141A, and well above the military specification (MILSPEC) requirements.


It is called guard because everybody is supposed to listen/guard the frequency just in case someone has a problem.

Guard definitions:

  a state of caution, vigilance, or preparedness against adverse
  circumstances
  watch over in order to protect or control.

The AIM 6-3-1(h)(1) says (emphasis mine):

  121.5 MHz and 243.0 MHz. Both have a range generally limited to line of sight. 121.5 MHz is guarded by direction finding stations and
  some military and civil aircraft. 243.0 MHz is guarded by military
  aircraft. Both 121.5 MHz and 243.0 MHz are guarded by military
  towers, most civil towers, FSSs, and radar facilities. Normally ARTCC
  emergency frequency capability does not extend to radar coverage
  limits. If an ARTCC does not respond when called on 121.5 MHz or 243.0
  MHz, call the nearest tower or FSS.


Can I obtain a license over several years?

I'm assuming you're asking about the US, since you mentioned sport/recreational licenses.

You can take as long as you like to learn to fly, although spreading it out over multiple years will actually cost more, not less. The reason is that you forget things and take a lot longer to develop the right reactions, muscle memory and feel for the aircraft. So try to fly as much as possible and do your license as quickly as possible, within whatever time and budget limits you have; I know that not everyone has the time and money to learn to fly in one month or even one year.

As for a ground school course, they're often planned to end with you taking the knowledge test required for private pilots and that test might even be included in the price. When you take the test it's valid for two years. If you don't pass your final checkride within those two years then you'll have to do the knowledge test again first. But that doesn't mean you have to do a ground school course again, you can work with an instructor and by yourself to refresh your knowledge.

But if you're not sure about how/when to start training then the best thing you can do is talk to an instructor about your situation and expectations. Any good flight school will be happy to have someone sit down with you and answer whatever questions you have. An introductory flight would be a great way to start, if you haven't already done that.


Does currency in one C172 model apply to other models?

@RyanGriffith is correct on the legal standpoint however its worth elaborating on your other point a bit

  This could be the case for a flying club that has many different
  versions of the same aircraft model. Perhaps on a nice day of flying
  the aircraft that you have been flying more recently has already been
  booked. You would still like to perform the flight with a different
  aircraft also offered by the club. However, it has been more than 3
  months since you have last flown that specific aircraft.

Most flying clubs, FBO's and anywhere else you may rent an aircraft from can impose other currency requirements and in many cases their insurance may require it. So while you may be legal to fly an aircraft that does not mean you always can, and in some cases if you do it may not mean the insurance will cover it should something go wrong. For example the flight school I fly out of has both fuel injected and carbureted 172's if you are checked out in the fuel injected one you are allowed to fly the carb'ed one but not the other way around. They also have similar requirements for their Cherokee's where you can fly anything with less HP than what you have been checked out in, for example I am checked out in their archer so I can fly that as well as their 161 warrior.

So in the specific case you mention for a flight club you should further confirm what their operating rules are.


How much simulator time can I use towards a part 61 instrument rating?

The simulator doesn’t meet the definition of aircraft.

§61.1   Applicability and definitions.
Cross-country time means—
(i) Except as provided in paragraphs (ii) through (vi) of this
definition, time acquired during flight—
(A) Conducted by a person who holds a pilot certificate;
(B) Conducted in an aircraft;
(C) That includes a landing at a point other than the point of
departure; and
(D) That involves the use of dead reckoning, pilotage, electronic
navigation aids, radio aids, or other navigation systems to navigate
to the landing point.
(ii) For the purpose of meeting the aeronautical experience
requirements (except for a rotorcraft category rating), for a private
pilot certificate (except for a powered parachute category rating), a
commercial pilot certificate, or an instrument rating, or for the
purpose of exercising recreational pilot privileges (except in a
rotorcraft) under §61.101 (c), time acquired during a flight—
(A) Conducted in an appropriate aircraft;
(B) That includes a point of landing that was at least a straight-line
distance of more than 50 nautical miles from the original point of
departure; and
(C) That involves the use of dead reckoning, pilotage, electronic
navigation aids, radio aids, or other navigation systems to navigate
to the landing point.


What are the differences between intertank valve and crossfeed valve?

In layman's terms, at least on a Gulfstream G450/G550, the cross-feed system allows the engines to be fed from either the left tank, the right tank, or both tanks (one to each engine.) the cross-feed pipes feed into the fuel hoppers, not directly into the other tank. While you can use the cross-feed system to fix a fuel imbalance, doing so would be via using the fuel (in the engines) not actually transferring it from tank to tank.

The intertank system is a valve and pipe system between the tanks themselves, allowing a fuel imbalance to be fixed by initiating/allowing the transfer of fuel from tank to tank directly.

My sources were:
G450/G550 Fuel System
G450/G550 Fuel Unbalanced


Vector to final on RNAV approach with the Intermediate and final segments are not aligned

Since most fatal accidents are during approach, it is important to maintain 100% compliance with the procedure and have a clear understanding of what your FMS will do with different modes.
There is an important Garmin / FMS distinction between:

Selecting "Activate Approach" mode when navigating to a fix leading to an approach sequence, and;

Navigating directly to the FAF via ATC vectors by selecting  "Vectors to Final" ("VTF") mode.

If you select Vectors to Final in G1000 or G3000 (likely similar to your G650), the following things happen (from memory, I may have missed a few):

The waypoints in the flight plan are bypassed (but remain inactive in the plan and available to re-navigate direct to) and the FAF is made active;

Approach mode is engaged (which increases needle sensitivity);

If you have a non-GPS approach loaded, the frequency for that approach is made active and the needles switch to the relevant indication (green needles for ILS for example);

If you are navigating to a GPS waypoint, the FMS turns off lateral guidance and engages roll-mode (if you are in Heading mode, that mode is maintained);

The HSI Bearing Needle is set to the final approach course (or outbound course for a back course approach);

A graphical magenta line representing an extension of the line between the touchdown zone and the FAF is drawn on the map.

It would be unusual to use VTF (in IFR conditions) without being under some form of ATC guidance on vectors and terrain clearance - Hence 'Vectors' to Final. The use for VTF mode is usually when the pilot receives a clearance as follows:

ATC: N188L, six miles from BABPI, turn right heading 280, maintain two thousand six hundred until established on final approach course, cleared RNAV runway 30 approach Byron Airport.
Pilot: Right turn 280, two thousand six hundred until established, cleared RNAV 30 approach, 88L.

(The italicized sections are meaningful; look them up in the Pilot Controller Glossary)
At that point (assuming already at 2600), the pilot

Affirms the correct approach is loaded in the FMS flight plan;
Dials in 280º on the heading bug;
Engages heading mode, and;
selects Vectors to Final and the Garmin will then auto engage the approach from the FAF inbound. (Since this is a LPV approach, the Garmin will also intercept the vertical flight path.)

A contrary but common clearance might also be:

ATC: N188L, cleared direct MOVDD, cross MOVDD at or above three thousand, cleared RNAV runway 30 approach Byron Airport.
Pilot: Direct MOVDD, MOVDD at or above three thousand, cleared RNAV 30 approach, 88L.

In this case, there is a distinctly different FMS sequence:

Affirm the correct approach is loaded in the FMS flight plan;
Select MOVDD in the flight plan (this will be either an IAF or an IF);
Select Direct To - Enter - Enter to make active;
Select FMS mode (if not already selected and skipping the part to make sure the ship does not jump uncomfortably towards MOVDD);
Engage Approach Mode;
The Garmin will now auto sequence the approach including auto selecting green needles to fly an ILS or VOR if required. The Garmin will also intercept the vertical flight path if available.

You state in your question ATC pointed us to the MOVDD IF before cutting us loose (informing us that we would be getting a vector to that fix)
So what you do is:

Enter Direct To MOVDD and fly that course;
Select Activate Approach when you are cleared to fly that approach;
If ATC gives you a vector (perhaps because ATC does not want you to go straight there) then you enter heading mode and use the bug for that vector. Reset Direct To when ATC stops vectoring you.
Even if you receive a vector, you continue to have MOVDD as the active waypoint and you do not engage VTF unless you receive a clearance and a vector related to that clearance with the intent of you ending up on the final approach course near the FAF or a linear extension of the final approach course.

For illustration, consider the approach to KEGE (below, with the Vectors To Final magenta line drawn.
If you were to select VTF well outside of the IAF for this approach (and you were not under ATC POSITIVE CONTROL) there is a high risk that you would hit the 11,200 foot mountain just 7 miles from the FAF on the magenta line.
If VTF is engaged at a time when the pilot does not understand the sequence or limitations, BAD THINGS CAN HAPPEN! The FMS itself does not maintain terrain clearance for you.


How are special flight paths coordinated with ATC?

Rules for ATC in the US are laid out in FAA JO 7110.65.

  The primary purpose of the ATC system is to prevent a collision between aircraft operating in the system and to provide a safe, orderly and expeditious flow of traffic, and to provide support for National Security and Homeland Defense.

It's up to ATC to use their best judgment as to how to accommodate the requests of the pilots while keeping the system safe and expedient for everyone. Pilot requests can always be denied, but of course the pilot has the ultimate responsibility for the safety of their flight.

Since ATC is specifically required to support National Security, the military already has reserved areas charted, called military operations areas, or MOAs, and Restricted Areas. The military has priority in a MOA, and when Restricted Areas are in use non-military aircraft need special permission to fly there.

For civilian flights, they are less likely to get a completely reserved area. ATC needs to know where the aircraft will be so they can keep them separated from other traffic. If pilots want a block of airspace for testing, where they can turn, climb, and descend without asking permission every time, they typically need to find some airspace where they can stay out of the way of other aircraft. Companies like Boeing may have agreements with ATC about certain areas that are available for this kind of usage, often out over the ocean

For special tests like the one in the question, the pilots have to plan out their route. The filed route uses GPS waypoints to complete the pattern:

  KBFI SEA NORMY J70 MLP GTF 4632N/08706W 4626N/08908W 4301N/09715W 4352N/09907W 4358N/09958W 4306N/10033W 4245N/09958W 4229N/09834W 4122N/10101W 4254N/10552W 4312N/10730W 4314N/10848W 4302N/10919W 4235N/10907W 4157N/10820W 4112N/10654W 3932N/10210W 3717N/10133W 3757N/10243W 3803N/10323W 3702N/10401W 3633N/10320W 3604N/10117W 2827N/09937W 2652N/09820W 2814N/09844W 3438N/09829W 3538N/09819W 3745N/09715W 3610N/09249W 3533N/08953W 3148N/08837W 3126N/08754W 3503N/08731W 3457N/08616W 3539N/08713W 3809N/08411W 3820N/08458W 3642N/08915W 3804N/09148W 3935N/09604W 4143N/09442W 4230N/09354W 4601N/08829W 4631N/08706W KBFI

The pilots must stay on their cleared routing and ATC will do their best to accommodate them. Of course if safety becomes a concern ATC may have to deviate them from their pattern. But knowing the flight path ahead of time, ATC should be able to have other flights in the area out of the way without much trouble.

This flight in particular was done overnight, when air traffic is lightest, which would have made separation much easier. Also, a lot of the path is in the western US, which also has less air traffic. Towards the end of the flight, once more fuel was burned off, the flight climbed to FL400 and higher which would have taken it above most other traffic. All of these factors would make ATC more likely to accommodate this sort of strange routing.

There are many other examples of this sort of thing:

787 and Boeing
logo
737 MAX
747
747-8
Seahawks
Gulfstream
Cessna


How do I tell ATC that I don't have a transponder?

From the AOPA:

  Flying into a Mode C Veil Without a Transponder

  For flying into a Mode C veil without an operable transponder, the
  pilot needs to telephone the appropriate radar facility for the Class
  B airspace and ask for permission to make the flight. Upon agreeing to
  conditions (including direction of flight and altitude), the pilot
  will be given a code number that he will mention to the controller
  upon initial radio contact. This is the same procedure that a pilot
  with an inoperative transponder/encoder would use to fly in or out of
  the Mode C-veil airports for avionics repair.

  The situation may be slightly different if the pilot is landing at a
  satellite Class D (towered controlled) airport within the veil but
  outside of Class B airspace. The approval is still given by the
  controlling radar facility via telephone. The radar facility may still
  issue the code number but may only require the pilot to contact the
  tower in the Class D airspace.

  NOTE: You should not expect approvals at the busiest of Class B
  airports during their peak times or under difficult weather
  conditions, but if this telephone procedure can expand the utilization
  of your aircraft occasionally, then by all means, phone to find if you
  can "fit into" the system.


What would the point to point range of the current Virgin Galactic Spaceship 2 launch system be?

This is going to involve a lot of speculation!

I'd guess that White Knight Two will have to fly at approximately airliner speeds once it reaches altitude, otherwise it will stall in the thin air. Total flight time of the combination is expected to be 2.5 hours, which gives a range of about 2500km (if we optimistically assume it does Mach 0.8 the whole time, the initial climb is likely to be much slower)

Spaceship Two is projected to have 6 minutes of freefall and a top speed of 4000 km/h, so that's another 400km. If they thrust at an angle rather than straight up the top speed may be higher but the flight time will be lower, so I think it's a reasonable estimate.

If it starts gliding from 50,000ft (15km) and has a glide ratio of 5:1, it can cover another 75km (so picking a glide ratio out of the air has very little effect on the total)

I doubt anyone will pay $250,000 to fly 3000km at basically the same speed as an airliner.


How are the NEO LEAP-1A engines attached on the A320?

This page shows a schematic of the mounts for the original A320.  There are 4 bolts and 2 shear pins at the front mount, and another 4 bolts and 2 shear pins at the aft mount. In general terms, the A320neo pylon and mount system design was kept very similar to the original A320 design.  So it's a good guess that the number of bolts is the same, although I was not able to find any source to confirm that.


Why do the stabiliser trim wheels not move exactly in sync?

The rear wing (horizontal stabilizer) of a 737 is effectively one piece. There is no separate left and right trim control. Both sides during assembly are attached as one.

This is just a visual illusion because the white marks are not aligned. If you manually move one wheel, both wheels will move.

It's worth noting that the white marks do not represent the position. For the full stabilizer travel, the wheels would make many, many revolutions.

The stab trim position indicators would show the position, not the wheels:

(source)


How is DME station ident coded in ARINC 429?

Labels 246 and 247 describe up to 4 7-bit ASCII characters.

1th char: Bits 11-17 of 246
2th char: Bits 19-25 of 246
3th char: Bits 11-17 of 247
4th char: Bits 19-25 of 247

For AGG, in ASCII we get 0x41, 0x47, 0x47, then:

Label 246 = 0x11D04A6
Label 247 = 0x11CA7

SSM encoding is the same as regular discrete labels.
I am not familiar with labels 242/244.


Should I inform ATC about minor deviations to maintain VFR while on practice instrument approaches?

Yes, definitely. Approach is expecting you to fly the approach as published and/or instructed and if you can't do that for any reason then you need to tell them. They may be providing separation between you and other aircraft, and if you start maneuvering without any explanation that could make things difficult for them.

The last time it happened to me I was being vectored when my safety pilot told me that another aircraft was heading towards us. I turned and climbed and then told ATC "maneuvering for traffic, will resume 3000 and heading 150 when able". The controller acknowledged, waited until I was (more or less) back on course and then gave me another vector.

Having said all that, if you can't fly the approach without deviating all over the sky then you should consider if it's really worth it. First, because it may not be very useful or realistic practice, and second because if you put a higher workload on ATC then they may just drop you completely. The ATC orders 4-8-11 say:

  [...] ensure that neither VFR nor IFR practice approaches disrupt the flow
  of other arriving and departing IFR or VFR aircraft. Authorize,
  withdraw authorization, or refuse to authorize practice approaches as
  traffic conditions require.


How to correct CG on a not leveled aircraft?

You have a problem because you would have to know where the vertical center of gravity is to be able to mathematically calculate a correction factor to apply to the weighing points.   The higher the vertical C of G is, the more rear weight bias you will get if the plane is nose-high from level, or front weight bias if nose-low.  How much to allow for?  You don't know.

When the plane is level, it doesn't matter where the vertical CG is.  You would be better off finding some other part of the structure that is aligned with the longitudinal axis from drawings or the maintenance manual, typically something like an upper fuselage longeron, to level the airplane.


Why do aircraft use hydraulics instead of pneumatics?

The big disadvantage here is the loss of precision due to the high compressibility of gas compared to liquid. Because gases are highly compressible, they provide a buffer to changes in pressure commanded by the operator to move the piston in the cylinder. That poses two problems; first, it means that the pneumatic cylinder doesn't respond instantly to pressure differentials, because the differential must first overcome the cylinder gasket's static friction. Second, it means that the movement of the cylinder is more easily opposed as long as whatever force opposes the gas pressure can overcome said pressure without causing whatever the pneumatic system is controlling to fail.

To overcome these shortcomings, most pneumatic systems run at very high pressures, so that the pressure differential between the two halves of the cylinder readily overcomes static friction and any other opposing forces. However, that creates another precision problem; high-pressure pneumatic cylinders are essentially two-state systems; the piston or actuator is typically at one or the other of its extremes of movement, and transitions between them very quickly as gas pressure is applied to one side or other of the cylinder.

None of these behaviors are desirable for aircraft controls; instructors labor daily to teach their students not to ham-fist the controls, instead using a bit of finesse to get the plane to do what they want in a smooth, controlled fashion. Why then, would you want to undo all that finesse with a control system that can only move the surface to the extremes of its travel?

Hydraulics, by contrast, allow a much higher degree of finesse. Because liquids don't readily change density, the pressure changes within a hydraulic cylinder require much more force to oppose, but by the same token, as the volume changes the pressure on the side being supplied with fluid decreases rapidly. This allows a hydraulic cylinder to be positioned much more accurately, regardless of any external forces acting on the system. The disadvantage is hauling a fairly heavy liquid up into the air, and having only limited capacity to replace it if any of it leaks.

Electrical actuators are a common solution to that disadvantage, especiually in light aircraft. Electrical actuators use an electric motor or servo to provide the mechanical action. These actuators can be controlled with a high degree of precision, and their "supply system" is just an electrical circuit, no heavy and complex hydraulic lines and cylinders. Their disadvantages are a tradeoff between speed of movement and maximum applied force while moving; you can either make an actuator that moves very quickly, or an actuator that will move no matter how much force is opposing the movement, but you really can't do both. They're still useful in light aircraft to control flaps (with a cable system used for the main surfaces), because they allow for precise amounts of extension or retraction, and don't have to instantly respond to input like the primary control surfaces do.

There is something on the horizon that could make pneumatics feasible for aircraft. Hydraulics systems were recently improved with the development of the electrohydraulic servo valve. This system uses a variable electrical potential (voltage) to move a hydraulic cylinder by a prescribed amount proportional to the voltage applied. Pure electrical servos have been around for decades, but the maximum amount of force available from a servo is insufficient for large airliners, while for smaller aircraft the servo motor's relatively high weight compared to simple cable controls is a disadvantage. The electrohydraulic servovalve concept is used in newer large aircraft to replace pure hydraulic or cable/hydraulic hybrid control systems, because the hydraulic system can now be controlled by an electrical circuit instead of hydraulic lines or tensioned cables coupled to the control column. This allows for "fly-by-wire" aircraft such as most Airbus airliners as well as most fighter jet designs of the last 40 years.

A similar concept is under development for pneumatics, allowing the precise placement of an actuator using pressurized gas in response to an electrical voltage. This would provide all the advantages of an electrohydraulic system, with considerably lighter weight and faster response, but still having the disadvantage that a significant opposing force could prevent movement of the actuator especially as it approaches the desired position. Whether that will be an issue in a large aircraft remains to be seen, and the weight savings of losing the hydraulic fluid might not be worth it, but if the tradeoff is acceptable, it would further increase range or payload of the next generation of passenger aircraft, with the added safety/reliability feature of being able to compensate for a slow leak in a pneumatic system by simply adding more air with a compressor pump.


If jets carried pure O2 to use for combustion, would they be more efficient?

Vehicles which carry their oxidizer with them are called rockets. It is a good thing that air is not pure $O_2$, because the nitrogen, being employed as a process gas,  helps to get useful work from the combustion process. By being heated and accelerated in the combustor, it does the main work of driving the turbine and turning heat into mechanical work. Engines would be even cleaner if less oxygen is around, because already at 21% $O_2$ they run at fuel-to-air ratios well below the stoichiometric optimum.

If you consider the amount of air flowing through the core of a modern turbofan, you will see that the amount of oxygen which needs to be available will dwarf the amount of fuel, and most of it would not burn but would replace nitrogen in its role as the process gas. It could not be carried with the airplane nor isolated from surrounding air if any meaningful payload and range should remain.

For some background on the combustion process, please see this answer.


Do the captain's and first officer's rudder pedals always move together?

In the EMB-145 and -135 the rudder controls are mechanically linked in the tail in an assembly that converts torque from the rudder cables to linear rod input into the rudder hydraulic control units.  Up until this assembly the rudders are technically independent and the cables for each rudder are routed differently through the airframe so that a single point of damage does not render the rudder inop.  The autopilot servo is only located on the captains rudder cables.  Through the rear linkage both pilots rudder pedals will move together when either provides input.

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


Can you get cheaper insurance with more experience?

It's not at all clear that more total flight hours correlates to lower risk. Data shows that pilots with <200 hours of total flight time are at the lowest risk of having a serious accident.

One can speculate the reasons for this, but the truth is, aviation accidents are still very rare occurrences. This makes gathering and analyzing data difficult. The data is very noisy due to the low sampling rate.

That said, statistical data points to a low rate of accidents until somewhere between 100 and 250 hours. Then it increases steeply, reaching its highest point around 500 hours for non-instrument rated pilots, and 800 hours for IR.

Annualized non-IR GA accident rates (median TFH=250.5)*

Figure 11. Annualized IR GA accident rates (median TFH=823.5)*

Statistics have long shown a "hump" in accident rates at the middle zone of experience.

From there it descends slowly over time but never reaches the low rates of new pilots. Another thing that occurs is that the number of pilots at a particular level of experience decreases extremely rapidly after a few hundred hours. It decreases to the point where the number of pilots with high hours is very small. The sample rate is then so small that it's close to impossible to come up with an accurate risk assessment.

Additionally, sometimes insurance rates are obviously driven by factors other than risk. Most aircraft insurance will give a discount for instrument rating. But if you look at the above graphs, IR pilots are at a higher risk than non-IR. They can fly in IMC, which is higher risk, but they have cheaper insurance. This is clearly a marketing decision. If one insurer gives you that discount where others don't it will attract more customers.

* Source: Predicting Accident Rates From General Aviation Pilot Total Flight Hours,William R. Knecht
Civil Aerospace Medical Institute, Federal Aviation Administration


When cruising, is any moment that a pilot will reduce his/her airplane speed?

What you're worried about is hitting turbulence. The word "impact" isn't typically used, although hail impacting an airplane has on relatively rare occasions damaged airplanes in flight and even more rarely has brought them down. My experience was that it just makes a lot of noise on the windshield.

Your question title is more inclusive than the body. Taking the narrower question in the body first— yes. If a pilot is expecting or experiencing severe turbulence, he should lower the cruising speed if that speed is above the recommended turbulence penetration speed. And in lesser degrees of turbulence, some might choose to lessen the speed if they believe that doing so will give passengers a less uncomfortable ride.

Now as to "any moment" and interpreting that as "any time", there are a few instances I can think of offhand.

I knew a few pilots that, when they were paid by the hour, would sometimes reduce speed, although I think that they would usually just not bring the aircraft up to the normal cruising speed rather than get that speed and then slow. To me that was unprofessional. I flew with one such captain a few times, and on my legs if I put the airplane (747-100/200) at to mach 0.86 for cruise, he'd ask for it to be slowed.
In specialized and rare instances, it might be desirable to reduce your speed to be a little more fuel efficient. For example, JFK to Tel Aviv in a 747-100 would usually require a redispatch at a fix abeam Athens. To be legal you had to have a certain minimum fuel at the redispatch point before proceeding to Tel Aviv, otherwise you'd have to land at Athens for fuel. So, if approaching the redispatch point — say an hour or two away from it — you might choose to slow to have a little more fuel on arrival at the redispatch point if you thought not doing so would result in a little less fuel than required.
Then there's the instance where you know you're going to be thrown into a hold on arrival at the destination so you may as well slow a little getting there, burn a little less fuel, have to hold a shorter time. You have to be careful with this one though, because it might mean others get into the hold sooner than you would have, and all you had done is put yourself farther back in the line than you would have.
And, of course, ATC may ask for a cruise speed reduction to minimize excessive flow at the destination.


Do pilots choose which aircraft to get rated for or is it the employer that decides it?

It depends. In the US and at airlines, seniority rules what aircraft, and what base you start at. Usually, there will be bases for pilots, that are then broken down by aircraft(though not all bases will have options for all aircraft types) and then Captain and FO spots for each group. For example at Delta, at one point, the new hires were going primarily 767 FO spots, at JFK. As their seniority in the airline increases, they can then try to bid to a different aircraft or a captain spot on any aircraft that their seniority can hold, or to a different base. Some may spend a bulk of their career as FOs and just like being a senior FO at a base or type, others will jump around slowly moving up and progressing through various options, depending on the individual.

In the US, and airlines, generally you don't pay for your training for the type ratings. Though, Southwest has in the past required applicants to have a 737, and a few others require the type rating already in hand.


Yes, yes and yes:

At that event the winds were 12-15kts.
There is some lift increase from propeller wash impinging on the inboard wing and flap. But most airplanes benefit from this (my own PL-2 has flaps that go all the way under the fuselage and the sink rate difference power on and power on is a lot).
Propeller thrust is contributing to the total lift as soon as the thrust line is tilted above horizontal, as a vertical component is added to the thrust vector. With a slatted wing allowing the wing to operate at up to 25 degrees AOA with the associated deck angle, engine power is starting to contribute a significant part of holding the plane up (if a 300lb thrust force is inclined 25 deg, the vertical thrust or "lift" component is about 130lbs), which is why it plummets the instant the power is removed (to better imagine the effect, just imagine you cankeep pitching the plane's deck angle to 90 degrees, where ALL of the lifting force is coming from the prop).

So, an ultralight like that should have no problem slowing to 21 or 22 kt in that configuration (a Zenith 701 can maintain control down to about that speed although its published stall speed is 30 mph or 26 kts), dropping another knot or two as it gets into ground effect, add in the head wind that was present, and you're down to a ground speed of a person running.
The headwind is kind of "cheating" in terms of absolute performance, but keep in mind that it's a competition between aircraft in those conditions on that day, so the headwind isn't a factor in the relative performance of the competitors, except to the extent it's varying at the time and small variations in wind speed are probably enough to give one plane a victory over others with more or less identical STOL performance.


Is there a method for calculating change in V-speeds with a change in weight for a Cessna 172?

Instead of doing detailed calculations like you were in a jet, there is a useful rule of thumb advocated by author/instructor William Kurshner for working that out, which while not exact down to a fraction of a knot, is conservative and easy to do and is therefore perfect for regular GA flying.

Reduce Vs/Vr by half of the percentage of the weight reduction.  So if stall speed is 50kt at gross, and the weight reduction from 2297 to 1807lb is about 21%, and half of that we can round up to about 11%, your stall speed is going to be about 45 kt at that weight.

So if I was using say, 55kt as a rotation speed at gross (I seem to remember that's what it was on the 172), I'd use about 49 kt at 1807 lb.  Close enough for 99.9999999999% of normal operation in a Chevy Biscayne Of The Air like the 172.


Do Red Bull Air Race aircraft make use of nitrous oxide injection?

This is from the 2014 season

http://airrace.redbull.com/en_US/article/lycoming-engines-power-behind-air-race

  In previous years, the race teams were allowed to modify their
  aircraft, but since 2014, the engines and propellers have been
  standardised for all teams. The Lycoming Thunderbolt AEIO-540-EXP
  engine and the Hartzell 3-bladed 7690 structural composite propeller
  have both undergone rigorous testing and have performed to
  specification.

Here's a link to a smaller engine using nitrous to get 300 HP out of a 100 HP engine for record setting purposes

https://books.google.com/books?id=DhLSUHx136QC&pg=PA36&lpg=PA36&dq=lycoming+io-540+nitrous&source=bl&ots=UwecpWRA8S&sig=RgiMHhHnQuHJYph0TASw0Y6bB2o&hl=en&sa=X&ved=0ahUKEwieiZTGqf7aAhVxUd8KHc5uBLoQ6AEIhAEwDA#v=onepage&q=lycoming%20io-540%20nitrous&f=false

and even more HP here

https://en.wikipedia.org/wiki/Bohannon_B-1


Why was the A340 developed with four engines?

Hindsight is 20/20.

At that time, nobody could be sure the ETOPS rule would be extended the way it eventually was. The 1985 extension was a gift from the FAA to Boeing, so US carriers could use the Boeing 767 for transatlantic services. The 1989 extension to 180 minutes allowed them to cover all domestic routes with a single type when before they needed three-engined types (TriStar and DC-10) to fly to Hawaii.

Not everyone at that time was in favor of introducing ETOPS: McDonnel-Douglas said in 1984:

  ETOPS "represents a 'totally new risk' that the industry has a limited capability to offset."

and

  "… the possible adverse consequences of premature extension of the operating limits can never be balanced by economic gain."

Especially Lufthansa had been sceptical of using two engines for long range and was a driver for the A340 development. Also, Airbus had experienced FAA chicanery before (remember that the A300 was banned for a while because of its slightly higher ground pressure loads). Airbus simply assumed that this kind of chicanery would be repeated when they went with a two-engined long range version.

That only changed when Boeing introduced the 777. Now Boeing was pressing for an ETOPS extension ("early ETOPS") and the FAA duly obliged. But that was in 1995, a full decade later and after Boeing had done extensive ground and in-flight testing, including running engines for a quarter of a million hours. ironically, the positive experience with the A320 in its first two years of operation helped to convince the sceptics of the merits of early ETOPS.


Why does the P-3 Orion use an engine driven compressor instead of bleed air for pressurization?

The T-56 engine, like all turboprops, is much more efficient at converting fuel into rotational energy than compressing air.  It takes approximately 50-100 shaft horsepower to run an EDC, depending on altitude and how cold of a temperature you select. Bleeding a small amount of air off the engine to run engine anti-ice costs you a 9% loss of SHP, which in flight, would be anywhere from 150-250 SHP.  I don't know the exact volume of bleed air you would need to run a pressurization system, but it is definitely more than the engine-anti ice system.  I'm making that assumption base on the size of the ducting.  The anti-ice tubing is much smaller than the EDC tubing, or the main bleed air manifold for that matter.
All in all, I think it's due to efficiency.  The EDC is more efficient for that motor, but is more complicated and introduces more possible malfunctions.  A P-3 requires a LOT of cold air to keep the computers from overheating, more than a C-130 (same motor) for sure.  I'm not sure if the C-130's back in the day also had EDC's, but they use bleed air nowadays.  So the designers went with whatever can move the most air.  I don't have my Orion Service Digests handy, but I bet there's a more thorough answer in there.  I'll check whenever I go back to work.


What is this instrument above the EGT in the Boeing 737?

This is a differential pressure and cabin altitude indicator.

The outer dial indicates the difference in pressure between the inside of the cabin and the outside in psi. During takeoff and landing, it must not be larger than 0.125 psi, as the note below the instrument says. If it exceeds 9.1 psi, the pressure relief valve will release the pressure to prevent damage to the airframe:

  Two pressure relief valves provide safety pressure relief by limiting the
  differential pressure to a maximum of 9.1 psi. A negative relief valve prevents
  external atmospheric pressure from exceeding internal cabin pressure.

(Boeing 737 NG FCOMv2 2 - Air Systems - Pressure Relief Valves)

The inner dial shows the cabin altitude in thousands of feet. During normal operations, it should not exceed 8,000 ft. This is a measure of the absolute pressure inside the cabin, converted to an altitude using the standard atmosphere (ISA) pressure profile.

Note: The instrument below is typically a cabin climb indicator showing the rate of change of cabin altitude in thousands of feet per minute:

(image cropped from here)

The EGT instrument in your image shows the Exhaust Gas Temperature of the APU and is typically installed further to the left on the overhead panel.


Are there any situations where it's beneficial to disable altitude reporting in TCAS?

The only time it would make sense as a normal or abnormal procedure to turn off altitude reporting is when your static encoder system is reporting no or incorrect altitude information. Especially in today’s world of mandatory Mode C and/or ADS-b in certain airspaces. ATC in those airspaces may have you cycle your system temporarily. Or, they could have you permanently  turn it off while you either land as soon as practicable or vacate the airspace until the system is repaired.


Will I have to do a checkout ride at a rental place if I'm already familiar with the aircraft type?

Generally they will make you do a checkout with their own instructor, at least this is the situation I have always encountered when renting from various places. Generally speaking, when you go to a new rental place they will audit your log book, put you in their system and make you fly with one of their instructors for a few reasons:

While your license was issued, presumably legitimately and your log book may be full of hours that are presumed to have occurred they still want to make sure you can do what you say you can.
Generally their insurance will require it. At least this is what I have always been told by FBO's/Flight Schools. Both of the places I fly out of, even require a recurrent 90 day checkup with an instructor to be able to keep renting (no matter how much you fly).

One thing to note is that none of these are FAA regulations, so you are legal to fly the PA-28 as long as you have your bi-annual and TO/LD requirements filled. The rental shops can how ever impose other rules as they see fit (mine does not allow flights to grass strips with the rental planes).

Note: some rental shops may also have differing gap policies on their insurance. It's worth asking about this up front and seeing if you need to carry any gap insurance.


How do radio communications work en-route for intercontinental flights over the oceans?

As Ron mentions in the comments aircraft flying transatlantic routes (or really any long route for that matter) may use HF radios operating in the 3-30MHz range to communicate over long distances. HF radio waves have the ability to "skip" off the ionosphere if directed properly and thus propagate over the horizon and beyond line of site.

You can find some various frequency info here.

Honeywell also offers at least one satellite based solution.

You can also find a lot of good info here under the "communication" tab.

As for knowing the exact position of the an aircraft, this answers covers most navigation methods out there.

This thread quotes FL300 (30,000 Ft.) as the minimum altitude for continuous coverage across the Atlantic as does ymb1's answer here (route dependent).


Can an experienced airplane spotter identify planes only by sound?

Yes it is possible, although it is kind of hard to prove it over the internet.

Generally the type of engine (propeller / turbo-fan / turbo-prop etc.) is quite easy to distinguish as they make very different sound. I can also tell a Rolls Royce engine from others because Rolls Royce engines make a quite "harmonic" and "warm" sound as it powers up.

Now here is the fun part: I correlate the sound with the type of the plane by comparing the Doppler effect as the plane passes by. It tells you how fast the angular velocity is in relation between you and the plane. The variation in loudness gives you the approximate distance to the plane - if the plane is far away, its loudness would change slowly. Combine that with the geographic location of yourself and the flight paths of planes, it gives you the speed of the plane.

The speed of the plane is important because it tells you the size of the plane. If I hear a loud multi-prop engine moving slowly, I'd bet a transport plane, something like a C130. If it is moving quickly, I'd bet an aerobatic aircraft.

The location where I live is directly under one of the SIDs of a major airport. Planes are usually ~3,000 feet when they pass above me. One thing I notice is that long route planes like Boeing 777 or Airbus A340 makes a noticeably louder noise. This is because these planes carry a lot of fuel on takeoff, and their climb performance is restrained compared to short haul airplanes, meaning they pass above me at a lower altitude, hence the louder noise. I cannot distinguish from sound if it is a B777, B747, A330 or A340, but I know it is not a B737 or A320 unless the pilots fly slow and low.

I confess I have an unusually good hearing ability. I often hear faint sound or noises which others cannot notice. I am also a musician.


What's the standard print size for a sectional chart?

The New York Sectional (the only paper one I have on hand right now) is 20 3/4 X 59 1/4 inches. You are correct, they are large and printed on nice thick paper.


Why do VFR-flights need a clearance in class D airspace?

Because class D is controlled airspace.
While you are correct that VFR-IFR separation is not provided in class D airspace, the major advantage compared to class E airspace is that, because VFR is subject to a clearance, ATC knows exactly where all VFR aircraft are, enabling ATC to provide very accurate traffic information and/or collision avoidance.

So why for example is a VFR pilot given the clearance (or is that an instruction) to maintain 4000 ft in class D airspace, if he is resposible for the separation, and not the controller?

ATC can certainly limit you to a specific altitude, but as a VFR flight ATC can never lock you on a specific heading (since you must also be able to turn to stay clear of clouds). All rules regarding right-of-way in the air are based on turning - not climbing or descending - so being instructed to maintain a specific altitude should not limit your abilities to follow the normal rules of right-of-way.
Although not technically required, ATC will often provide some sort of separation between VFR and IFR in class D, at least in cases where there is an obvious risk of collision. But the normal separation minima do not apply, and ultimatively it is pilot responsibility to practise see-and-avoid (which is made significantly easier compared to class E or below because ATC can provide accurate traffic information).
If we go one step "up" the ladder, to class C - where VFR-IFR separation is provided - a major difference for VFR is the requirement for a mode A/C transponder. A transponder is normally not required in class D for VFR traffic, which is another reason ATC is not necessarily able to provide IFR-VFR separation in class D.
There are different use cases for the different airspace classes, and different countries and ANSP's will make use of them as they see fit in their local environment. The existance of the different airspace classes makes it possible to graduate the service provided to suit most situations:

Class G: No separation
Class F: No separation, but advisory service
Class E: IFR-IFR separation, no radio/transponder for VFR
Class D: IFR-IFR separation, radio+transponder required for VFR
Class C: IFR-IFR and IFR-VFR separation
Class B: IFR-IFR, IFR-VFR and VFR-VFR separation
Class A: IFR-IFR separation, VFR not allowed


Is there any reason to have ADS-B out that is not based on GPS?

There are still quite a lot of aircraft that do have ADS-B based on inertial navigation position.

The reason for this is quite simple; they don't have GPS or the GPS is not connected to the transponder. Somewhere during the lifetime of the aircraft the transponder has received an update or has been replaced and is now transmitting ADS-B messages, based on the only position source available to the transponder; the Inertial Navigation System. That is fully legal, but it does not meet the ADS-B requirements of the various ADS-B mandates around the world.

Is this a danger to the safety of flight when ADS-B IN based systems like ATAS are used?

No, not at all. ADS-B IN systems do not use the data from these aircraft as the ADS-B messages contain several quality indicators that must meet certain conditions before a track is being displayed in the cockpit. Transponders transmitting INS positions indicate that the position integrity and accuracy is very low. In addition the source integrity level (SIL) will also be set to 0. Each of these indicators will result in the track not being displayed.


Are the same units used for stations and waterlines?

Coordinates should always be in the same units. For a US manufacturer, that will be inches. The SI units are generally millimeters. This makes it much easier to locate coordinates, and for calculating things like volumes or distances.


What is the lighting technology behind the Dreamliner's dynamic interior lighting?

This 'mood' lighting is offered by Boeing in 787 and Airbus in A350XWB (as an option) and is achieved by using Light Emitting Diodes (LED). According to Airbus,

  Airbus is applying the latest technology in energy-efficient LED (light-emitting diode) mood-lighting on the A350 XWB. This enables the cabin ambience to be tailored to each airline’s own identity, as well as mimicking natural sunrise and sunset illumination that helps the body adapt to jetlag on long-range flights.

The main advantages of LEDs over conventional lights are,

The LEDs are longer lasting (~50,000 hrs).
They are more energy efficient.
They generate less heat.

Phillips seems to be involved in the development of lighting systems for the(se) aircraft. According to led-professional.com,

  Philips Lumileds provided the LEDs while Diehl Aerospace engineered the overall lighting system for the Boeing and Airbus cabin interiors.

The light intensity and colors are decided by the airliners and are pre-programmable (and can be changed remotely). According to Bloomberg,

  The Finnair A350 cabin has two dozen light settings, aligned with stages of a long-haul flight. It will also feature warmer, amber colors on flights arriving in Asia and cooler “Nordic blue” hues when flying into Finland. ...
  Virgin Atlantic has five primary color periods on its 787 flights: rose-champagne for boarding, purple-pink for drinks, "amber" for dining, another for the pre-sleep period called “work-rest-play,” a silvery glow for overnight sleep, and a waking color.

Similar lighting systems are also offered by third parties for other aircraft.


Can gusts be reported as lower than wind speed?

WMO standard defines a gust as the maximum wind speed exceeding the "mean speed" by 5 m/s (10 knots) during the 10-minute interval. With this definition, I would never expect to see a negative gust factor.
However, the FAA defines it differently (FMH-1):

5.4.3 Wind Speed.
The wind speed shall be determined by averaging the speed over a 2-minute period.
5.4.4 Wind Gust and Squall.
The wind speed data for the most recent 10 minutes shall be examined to evaluate the
occurrence of gusts or squalls. Gusts are indicated by rapid fluctuations in wind speed with a variation of 10 knots or more between peaks and lulls.

Thus, by my interpretation, a U.S. airport METAR can report gust speeds below the mean reported wind speed since it only requires a variation of 10 knots, not an exceedance of 10 knots.
However, reading further in the same document:

5.6 Summary of Wind Observing and Reporting Standards
Wind speed: 2-minute average speed in knots is reported.
Wind gust: The maximum instantaneous speed in knots in the past 10 minutes is reported.

It seems impossible to have a 2-minute average speed which is higher than the maximum instantaneous speed over the past 10 minutes. So following that, it would seem to indicate an error in the measuring or reporting equipment.


What does "clear of clouds" mean in FAA FAR part 103?

It means you have to stay outside the cloud while flying. You're expected to use your own good judgment (remember it is illegal to fly into the cloud, and if you don't have proper instruments and know what you're doing, it's downright deadly) but there is no minimum clearance as there is at other times, so if you really felt like a daredevil you could reach out and touch a low-hanging "popcorn cloud" with your wingtip. This term is often used in situations where vertical separation minima from clouds is not practical (to stay 500 feet underneath a VMC-friendly cloud layer would require altitudes as low as 500 feet AGL; there are a lot of hazards to navigation at that height from radio antennae to city skylines)


Why would smoke enter the cabin if the batteries are switched off before the APU flap closes?

Switching off the battery too soon interrupts the auto shutdown sequence.

In that sequence is an automatic de-oil procedure that is carried out. A de-oil valve introduces air into the oil pump to break the suction (reduce the drag) for the next start.

The air forces the oil back to the oil reservoir and out of the bearing chambers. If it doesn't the once warm oil will contract and add extra forces to overcome when it's cooled. The second benefit of the system is starting the APU in cold weather, with all the oil back in the reservoir, it can be uniformly heated before it is reintroduced into the lubrication system.

If that didn't happen, the next start will stress the oil system, a small leak may occur, which will burn and re-enter the cabin as burned oil (smoke).

If unsure about the last shutdown, the APU can be started and left running with no load whatsoever for 5 minutes to make sure it doesn't happen.

Also see this [somehow related] story on avherald.com. The mentioned Airbus publication link is broken, you can find it here.

Here's the APU shutdown sequence:

  At 95% speed, APU "AVAIL" lights go off.
  At 50% speed, the de-oil solenoid valve opens to decrease drag during the next start.
  At and below 7% speed:

  the de-oil solenoid closes,
  the APU fuel LP valve closes,
  the data memory module is updated,
  the air intake flap closes,
  the ECB de-energizes itself.

  (Airbus training manual.)

Do not use for flight.


Do propellers have any lead/lag mechanism?

The two things are completely different and exist for different reasons:

Fan and turbine blades are mounted loosely, so they can self-balance. This is because at the very high RPM fans and turbines spin at they are extremely sensitive to imbalance. On the other hand, the self-balancing only works at high RPM. It also requires the blades to be connected at the tips with the “shroud”.
Rotors have lead-lag hinges because the rotor spins parallel to the flow so in forward flight the advancing blade  meets the air at significantly higher speed than the retreating blade.

Propellers spin slower, so they are not as sensitive to imbalance, and they don't have the shroud, so they can't be mounted loosely anyway. They spin perpendicular to the airflow, so all blades meet the air at similar speed and angle of attack, so they don't need to deal with as big differences in the aerodynamic forces. And they are smaller and more rigid.


Is the rotor described in this Kickstarter new?

The rotors on that drone are of the centrifugal fan type. They are not new in design (don't know about aircraft use though) and can be found in all kinds of everyday appliances: hairdryers, vacuum cleaners, car A/C blowers, etc. They move air at a 90° angle, sucking it in from the top and expelling it from the side.

Apparently they are more silent in this application than a normal propeller (or so the kickstarter claims) but it is easy to spot some downsides. Weight for one thing, as it seems they need a lot more material for construction than a normal prop.


What aircraft design elements contribute the most to sustained flight?

Natural stability would be highest on the list for me. Look at free flying model airplanes for inspiration. They have their own characteristics:

Very low wing loading for minimum sink speed
High natural stability, and consequently a very narrow speed range
High aspect ratio wing, thin airfoil with high camber
Extremely short fuselage ahead of the wing (no payload to carry)
Extreme fuselage length aft of the wing which provides ample aerodynamic damping
Strong dihedral of the outer wing.

This in combination means that your control software can be very simple. Relaxed stability will require many sensors and built-in redundancy, and the more parts you need to add, the more possibilities of failures you will end up with. In contrast to that, the laws of physics never fail, use them to your advantage. See below for an example which I copied from the Wikipedia page on free flight models:

For airfols, c.g. location and all other details I recommend to look at several free plans until you see a common pattern.

Regarding the type of fuel: Depends how noisy and messy you tolerate the engine to be; some people will only fly electric while others are happy with two-stroke engines.


How much thrust could a 400 mm EDF produce?

It can be safely assumed that thrust $L$ is a function of the input power $P$, the diameter $D$ of the gas jet and the air density $\rho$.

Thus, $L = f(P,D,\rho)$

where $f$ is a function to be determined.

From dimensional analysis, the thrust $L$ can be easily derived:

The variables are Thrust $L$, dimensions $MLT^{–2}$; Power $P$, dimensions    $ML^2T^{–3}$; Gas jet diameter $D$, dimensions $L$ and air density $\rho$, dimensions $ML^{–3}$

The variables form a non-dimensional product $k$

$k = L^a\cdot P^b\cdot D^c\cdot \rho^d$  where $a,b,c,d$ are numbers to be determined.

Let’s form now a parallel product $k^*$ with the dimensions:

$k^* = (MLT^{–2})^a  (ML^2T^{–3})^b  (L)^c (ML^{–3})^d$

Clearly, $k^* = M^0 L^0 T^0$... We now take the exponents for each dimension:

$a  + b + d = 0 \\
a + 2b + c – 3d = 0 \\
–2a – 3b = 0$

We make $a = 1$, since $L$ is the variable we’re going to solve for.

$b = –2/3 \\
d = –1/3 \\
c = –2/3$

Then,

$k = L^a\cdot P^b\cdot D^c\cdot \rho^d \rightarrow  k = L\cdot P^{–2/3}\cdot D^{–2/3}\cdot \rho^{–1/3}$

Solving for $L$

$L = k\cdot P^{2/3}\cdot D^{2/3}\cdot \rho^{1/3}$

where $k$ is a constant

Hence, for gas jet diameters $D_1$ and $D_2$, and for the same power and air density, the corresponding values of thrust $L_1$ and $L_2$ are:

$L_1/L_2 = (D_1/D_2)^{2/3}$

For the case of $D_1 = 400 mm$ and $D_2 = 200 mm$, $L_1/L_2 = (400/200)^{2/3} = 1,59$

In other words, the larger (400 mm) gas jet gives you, for the same absorbed power and air density, 59% more thrust than that attained with the smaller (200 mm) jet.

Of course, this is an approximation valid for not too high aircraft speeds, based upon momentum theory, but gives you an idea...  For different values of power and gas jet diameter, you can derive the constant k from the data of thrust, power and diameter you already have,  $k = L\cdot P^{–2/3}\cdot D^{–2/3}\cdot \rho^{–1/3}$  and then use that constant in your calculations.


How to become a expert in Flight Operations Business? (Flight Dispatch, Weight and Balance etc.. )

It depends on where you are located and what country you are located in as to what kind of license will be beneficial to you. If you are in the United States, obtaining a FAA dispatch license is a common route to working in flight operations. There are community college programs to prepare you to take the exams. The benefit to the FAA license is it never expires. In other countries there are similar licenses you can obtain. I would be cautious to IATA programs mainly due to the price and many are geared towards existing professionals in the industry.


How does a turbofan with afterburner continue to function in extreme humidity and rain?

The air is compressed in the compressor section of the engine and heats up. Hot air is able to hold disproportionally more water in gaseous form than cold air, so all that water will vaporize and enter the combustion process together with the air. Since it is already vaporized, it will not absorb that evaporation enthalpy again that makes water such a good extinguishing agent. On the other hand, since the evaporation enthalpy was sucked from the air in the compression process, the air will be cooler when it enters the combustion chamber, so more fuel can be burnt (up to the stoichiometric ratio of course) and power can be increased.

This trick was used on high performance piston engines and early jets. The Boeing 727 would inject water into the compressor on purpose on hot and high take-offs to increase engine thrust.

If the amount of water entering the engine overwhelms the absorbing capacity of the hot air, the engine runs the risk of flaming out. Regular precipitation does not pose this threat, however.


Why not increase the number of Flight Data Recorders and add jettisoning capability?

The simplest argument to me is that no location on the aircraft is particularly special when it comes to locating black boxes in this sense. The recorders that aren't found are either in exceptionally remote locations or underwater - I don't see anything special about an engine that makes it more likely to be found than the wreckage of the fuselage.

No matter where you place them, there are going to be circumstances where they can't be found.


How IATA Code is requested or assigned to an newly built airport ?

Airports are assigned IATA codes when an air servicer (airline, cargo operator, etc) requests a code for an airport. The code is requested by filling out a form on the IATA web site.

This is not done by the airport management because it is meant to be for use by a commercial operation, and not the airport itself. IATA codes don't really have a lot of meaning to pilots and other general airport users. They are of use to air travelers and cargo operations as a means to identify airlines, destinations, baggage codes, accounting codes, and traffic documents. It is designed as a standard for industry wide usage, otherwise airlines may use many different codes/abbreviations for the same thing (an airport for example) that don't mix well with other airline systems.

So after your airport is built (or while it is being built), an airline or cargo operation may (or may not) request an IATA code for the airport. Participation in the IATA program is purely voluntary, and it may be that your airport doesn't handle services that conform to IATA.


How do you know which fuel an aircraft uses?

The actual fuel type limitations will be listed in at least two places: the aircraft type certification data sheet (TCDS), and the limitations section of the aircraft Flight Manual, Operating Handbook, or equivalent.

The fuel placards placed at the fuel filler ports might not list all approved fuels, or may state "Type X fuel only" when additional fuels may in fact be approved. These placards should be understood as a precaution against inadvertently fueling with an unintended or wrong type of fuel. In some cases ignoring these placards can have fatal consequences.

Some aircraft do indeed have approved emergency fuels. This information would also be found in the limitations listed above.

For example, the TCDS for the Beechcraft King Air B200 with PT6A series engines is lists the following for normal approved fuels:

  Fuel
  JP-4, JP-5 (MIL-T-5624); JP-8 (MIL-T-83133); JET A, JET A-1, and
  JET B conforming to P&WC S.B. 1244 or ASTM SPEC. D1655; in addition for
  B200 and B200C Chinese No. 3 Jet Fuel. See NOTE 6 for emergency fuels

Note 6 in the TCDS reads as follows:

  NOTE 6. Emergency use of MIL-G-5572:
  Grades 80/87, 91/98, 100/130, and 115/145 are permitted for a total time period not to exceed 150 hours time
  between engine overhauls. It is not necessary to purge the unused fuel from the system when switching fuel
  types.

Likewise, the EASA TCDS for the King Air B200 lists the same limitations.

The Flight Manual for the King Air B200 also lists these limitations, as applicable, as well as some additional altitude constraints when using emergency fuels due to electric boost pump requirements.

In contrast to the actual fuel limitations, the placard placed at the fuel port for the King Air B200 lists very little of the actual limitations:

Source: Beechcraft King Air 200 Maintenance Manual


Does the A320's FMC automatically adjust the rate of descent on a non-precision approach?

Your mentioning of LOC BC is interesting.

The answer is yes except for LOC or LOC BC approaches.

When the FMGS guides the plane down an approach, it is called managed. If manually selected (e.g. vertical speed or FPA), then it's called selected.

An A320 can fly a fully managed (lat/vert) NPA if it is VOR, VOR/DME, RNAV, or NDB (given that the approach is correctly intercepted and GPS primary is available or the navigational accuracy is good). If all engagement conditions are met, the 2nd and 3rd columns of the FMA will merge and read FINAL APP (you can watch this switch here), and will be flown down to the MDA, after which (by 50 feet) the AP disconnects.

Note: the coded approach needs to be validated and approved by the operator.

If the NPA is LOC, the official SOP is to fly it in LOC mode for lateral and selected for vertical – while calling out the raw data. That's because in a LOC approach the vertical deviation (that appears on the PFD in place of the glide slope) must be ignored because the MAP (missed approach point) could be before the runway.*

* No other reason is given, which may hint at a database limitation (possibly for safety reasons). Boeing's flavor, IAN (which is newer), allows G/P vertical guidance for LOC and B/CRS approaches.

Reference: A320 FCOM, SOP § 3.03.19.

I checked the A380, and its newer FLS (FMS Landing System) allows vertical guidance for LOC and LOC BC approaches, but with a caveat similar to the A320 (but in a more clear manner):

  However, the FLS function is not available, if the NPA is as follows:

  The Missed Approach Point is before the runway threshold, and
  The difference between the final approach course and the runway course is more than 50°.

  When the flight crew selects an NPA, and if the FLS function is not available for this NPA, the NO FLS FOR THIS APPR message appears on the FMS message area. [A380 FCOM § 22-FG-70-80-30]


Why is "clearway minus stopway" used in V1 adjustments?

What is the difference between clearway and stopway?

The definitions linked in the question for a clearway and stopway are fairly adequate.

AC 150/5300-13A Airport Design

Clearway - is an area extending beyond the runway end available for completion of the takeoff operation of turbine-powered aircraft. A clearway increases the allowable aircraft operating takeoff weight without increasing runway length.  No object or terrain may protrude through the clearway plane except for threshold lights no higher than 26 inches (66 cm) and located off the runway sides. The area over which the clearway lies need not be suitable for stopping aircraft in the event of an aborted takeoff.  A clearway must be under the airport owner’s control, although not necessarily by direct ownership. The purpose of such control is to ensure that no fixed or movable object penetrates the clearway plane during a takeoff operation.
Stopway - is an area beyond the takeoff runway centered on the extended runway centerline and designated by the airport owner for use in decelerating an aircraft during an aborted takeoff.  It must be at least as wide as the runway and able to support an aircraft during an aborted takeoff without causing structural damage to the aircraft.

Opa-Locka Executive Airport (KOPF) has both a clearway and a stopway at the end of runway 12:

The 1,000 ft of clearway extends to the end of the area.  The stopway is shown with yellow chevrons.

Why is clearway minus stopway used in V1 adjustments?

To answer this question some background information must be given.  A clearway is used for turbojets where the airplane manufacturer provides accelerate-go distance calculations.  A stopway is used for turbojets where the airplane manufacturer provides accelerate-stop distance calculations.  Neither clearway nor stopway distances can be used for turbojet aircraft that use a balanced field length concept.

Aircraft with unbalanced field length calculations can use the clearway for accelerate-go calculations and the stopway for accelerate-stop distances.  The idea is to allow the aircraft to increase their maximum takeoff weight by utilizing those airport features.

A change in V1 speed has the effect of increasing one of the takeoff distances while simultaneously decreasing the other takeoff distance.  For example, if V1 is decreased, accelerate-go distance is increased while accelerate-stop distance is decreased.  There isn't an easy way to calculate a max allowable takeoff weight (MTOW) by adjusting both V1 and aircraft weight.

To make the calculation easier some practical things are implemented.  A stopway will always be equal to or shorter than a clearway.  This effectively increases the length of the runway to the end of the stopway for performance calculation reasons.  At this point, we can go into the performance charts for both accelerate-go and accelerate-stop and come up with a MTOW.  Since both calculations are using the same distance we need to adjust the accelerate-go distance by the difference between the clearway and stopway.  We can then adjust V1 by the appropriate chart in the aircraft AFM by that difference.

We can perform an accelerate-go and accelerate-stop distance calculation again to come up with a corrected MTOW.


What noise reduction measures were taken in the time between hush kits and chevrons?

Generally speaking one is an add on and the other is integrated into the design. Over the years the FAA has implemented progressively more stringent noise regulations both for aircraft that are flying as well as to the full certification process. The changes came in stages and have been progressively altered for the past 30 or so years take a look at §36.103   Noise limits for the current regulation .  You can find some of the FAA legislation here and the full text of the relevant FAR's here. As such newer engines will incorporate noise mitigation directly into the design as they need to pass the certification process. However in cases relating to older designs it may be cost effective to design an attachment (like a hush kit) that can be added to an existing engine to comply with regulations since the engine was certified at a time that the regulations were far more relaxed. Due to the letter of the law planes can be grounded for being non compliant so a hush kit may be cheaper than a new plane. For example this was the case with the Lear 23 which had required hush kits.

Interestingly at least one patent for a hush kit stresses that it is for an existing engine design.

  BACKGROUND OF THE INVENTION

  The present invention relates generally to
  jet aircraft turbine engines and, more specifically, to a hush kit for
  use on an existing engine and airframe.

You can similarly find the patent for the chevron here. Which describes it more as part of the engine than as an add on.


Who is responsible for avoiding collisions on the ground; the pilot or the air traffic controller?

At all times, whether in the air or on the ground, whether at the gate or taxiing, the pilot-in-command (PIC) has final and ultimate responsibility for the safe operation of the aircraft. Per ICAO Annex 2 (with similar statements/definitions by individual civil authorities):

  The pilot-in-command of an aircraft shall, whether manipulating the controls or not, be responsible for the operation of the aircraft in accordance with the rules of the air, except that the pilot-in-command may depart from these rules in circumstances that render such departure absolutely necessary in the interests of safety.

As you stated, the pilot is allowed to deviate from any ATC instruction or regulation to the extent necessary to ensure the safety of the crew, passengers and property. If necessary, the PIC may enlist additional resources, such as a ground crew, to deal with issues like not being able to see behind the airplane. For airline operations, this is usually spelled out by the airline's operations procedures, which the PIC effectively "approves" (as the ultimate authority for the aircraft's operation) and carries out.

Air traffic controllers have what you might call "jurisdiction" over certain parcels of airspace and airports. The gates and the area immediately surrounding them are usually not under the jurisdiction of the control tower. They are instead managed by the airport authority. At large airports, the airport may operate a "ramp control" system with its own (smaller) control tower and radio frequencies. Arriving and departing aircraft coordinate with ramp control to get into and out of the gates safely. Ground crews will assist the pilot-in-command with parking and pushback operations, getting the aircraft to a point where the PIC can taxi the aircraft to leave the ramp area and enter the taxiway system in accordance with ATC taxi instructions.

Once on the taxiways, and from there to the runway and into the air, the aircraft is under the jurisdiction of the regular air traffic controllers. The controllers can divide up this area between different positions, usually a "ground controller," a "tower" or "local controller," and one or more approach/departure radar controllers.


How can we avoid running out of airport abbreviations?

Only major airports get all Letters.   Many of the smaller airports also incorporate numbers.

Here are some examples:

Osage City: 53K
Cle Elum: S93
De Vere: 2W1

And many, many, many more...
Once you add in letters and numbers, you'll find plenty of combinations.