Can plane climb without increase pitch angle?

Basically a plane will climb, descend or maintain altitude depending on two things: the angle of attack of the wing, and airspeed.
So, yes, it is possible to trasition from level flight to climb just by increasing speed, because as the speed increases, there is more airflow around the wing, and it will create more lift.
Also, generally planes have a natural tendency to pitch up if speed is increased and nothing else is done, further adding to the climb speed. Aeroplanes tend to "try" and maintain the speed they are trimmed to, hence the upward pitch as the plane is seeking to shed the excess airspeed by transitioning the extra energy into altitude gain.


Why doesn't the black box also record video?

Why does the black box still only record the cockpit's audio

The Black Box

There isn't a single black box. There is normally a Flight Data Recorder (FDR) and a separate Cockpit Voice Recorder (CVR) in large civilian transport aircraft. These are not mandatory in military transports or smaller aircraft.
Under proposals made in the last decade or two there would probably be a separate video recorder that records the flight instrument panel, recording what information the displays are showing the pilots and the positions of switches. So far as I can find, there are no official proposals to record external views - which are usually likely to be much less useful in determining the cause of an incident if you have FDR and CVR data.

Opposition

  the National Transportation Safety Board in the United States has proposed the idea of featuring cockpit video recording in airliner cockpits several times since the year 2000. However, such proposals have largely been opposed, especially by pilot unions who view such a stipulation as an invasion of privacy. NTSB has never been met with support for such a requirement from the FAA, since first proposing it in the year 2000.

(my emphasis)

From ICAO is Not Calling for Cockpit Video Cameras in New Airplanes. Aviation Today. 2017.

  Pilots don’t see the disappearance of Flight 370 as a reason to embrace cameras. They cite two reasons for their opposition: Video surveillance will almost certainly be misinterpreted or get into the wrong hands, and it can adversely affect how they do their jobs. “What a camera can capture can be so easily misunderstood and misconstrued,” says Doug Moss, a former test pilot and accident investigator.

From Why Pilots Hate the Idea of Cameras Watching Them Fly. Wired. 2014.


Is cabin air freshened when a plane is taxiing or on the ground?

The aircraft when on ground and starts to board passengers is switched to ground power or auxiliary power which runs the air conditioning system. When disconnected, the engines supplies the power and bleed air for the cabin pressurization.

"On the ground, the airplane is unpressurized and the outflow valve is wide open. During preflight, the pilot sets the cruise altitude on a cabin pressure controller. As soon as the weight is off the main wheels at takeoff, the outflow valve begins to close and the cabin starts to pressurize."

Source -
https://www.airspacemag.com/flight-today/how-things-work-cabin-pressure-2870604/


Can I rent a Cessna for a week with my GF with a PPL?

Most people do not take 45 hours to get a PPL, the national average is closer to 70. Do not fall for the "get your license in 45 hours" gimicks. They will give you 45 hours of instruction (and you will probably need more), you also then need to book the examiner and pay for that. 45 hours is difficult to do in short periods of time as well, for example I got my license in 47 hours, way below national average, and it took me 7 months (weather/work/instructor availability/aircraft availability/etc).

So theoretically yes, you can, if you are renting from the same place that you took your training. If not, then you will probably have to pass a check-out which will include about half an hour of ground and an hour or so of air with the company renting the aircraft. You may also not be allowed to rent overnight unless you have X number of hours, again this is up to the rental company.

You also need to have insurance which meets the rental company's requirements. Some rental companies won't rent aircraft overnight, so you need to check that, and if they rent for longer periods of time you will end up paying extra even while the aircraft sits on the ground.

For example, a local company will rent one of the 172's for up to 4 days. The regular rental rate is \$125/hr and overnights are charged $375 for each day.


How does stall risk in paramotors differ from that of conventional fixed-wing aircraft?

I suppose with paramotor you mean a powered paraglider, as pictured below.

Paramotor (picture source)

Since they obey the same laws of physics, they also stall, just like a fixed-wing aircraft does. There are, however, some peculiarities which should be mentioned:

The shape of the wing is produced by ram air filling the parafoil, so speed will help to keep the wing inflated and in shape. At low speed and in gusty winds the risk of the parafoil collapsing (severe deflation) is higher. This was the reason for several fatal accidents in the early times of paragliders, when the aspect ratio of high-performance parafoils was increased beyond safe limits. Today's designs will normally quickly recover from a deflation event, but not without a substantial loss of altitude.
The pressure forces on the parafoil will change its shape depending on its angle of attack. At low speed the angle of attack is higher, resulting in a suction peak close to the leading edge which in turn will increase the local camber of the foil. This leads to severe lift loss in a stall, and recovery needs some altitude. A fixed-wing aircraft, on the other hand, can employ an airfoil with only little lift loss in a stall, so recovery needs less altitude. This is by no means universal - there are also fixed-wing aircraft with less benign stall characteristics.
If the stall on a fixed wing starts near the wing tip, the aircraft might enter an uncontrollable roll. This can happen in steep turns and with badly designed aircraft. This is not possible in a parafoil; it might instead slide sideways with a partially collapsed parafoil, but stay upright due to its low center of gravity. If the pilot panics and pulls his brake lines on one side during a stall, the parafoil can enter a spin. Similarly, if the pilot of a fixed-wing aircraft insists on applying rudder when stalled, the aircraft can also enter a spin.

Generally, due to their low wing loading and the drag of the raiser lines, paramotors fly at much lower speeds than aircraft, so accidents involve less energy, but the pilot has no protection around her/him, so fatal accidents do occur more regularly than with fixed-wing aircraft. For paragliders, Wikipedia gives a number of 2 fatalities per year for 10.000 pilots.


To expand a bit on the other explanations here, "flow cones" are one of the many methods used for flow visualization.

When something is being tested in a wind tunnel or in flight, you usually can't see the air flow around the body. To be able to visualize the flow, something is added to the air, like smoke, or to the body, like flow cones or tufts. Tufts are basically just short lengths of string taped to the body at one end. Flow cones are small cones attached at their apex with string.

These items on the body have two main functions. Primarily, the flow cones or tufts will align them selves with the flow, allowing observers to see the direction of the air flow in that area.

They can also show flow separation. When the flow is attached to the body, it flows fairly smoothly along the surface. When the flow separates from the surface, it becomes much more turbulent and chaotic. The tufts or cones will show this as they are moved by the air.

Flow cones are larger than tufts, so they are much easier to see, which is important in cases like the picture you posted, where they will probably be observed from a chase plane at some distance.

For more on flow separation, see this question, or this video of tufts on a stalling wing. For a comparison of tufts and cones, zoom in on this photo of the X-29A. The darker, larger objects behind the cockpit are cones, while the reddish, smaller ones further aft are tufts. You can also see smoke at the nose being used to visualize the flow.


What is the minimum recommended cruising altitude to avoid bird strikes?

AIM 7−4−1. Migratory Bird Activity
a. Bird strike risk increases because of bird migration during the months of March through April, and August through November.

b. The altitudes of migrating birds vary with winds aloft, weather fronts, terrain elevations, cloud conditions, and other environmental variables. While over 90 percent of the reported bird strikes occur at or below 3,000 feet AGL, strikes at higher altitudes are common during migration. Ducks and geese are frequently observed up to 7,000 feet AGL and pilots are cautioned to minimize en route flying at lower altitudes during migration.


Why would a pilot want to land with less than full flaps?

Less flaps gives a faster approach speed. In some scenarios, a faster approach speed is better than a slow one, for example:

Strong crosswind
Possible wind shear
One-engine failure

A higher approach speed provides a better stall margin and higher control authority in challenging situations. For example, the Boeing 737 QRH calls for a flaps 15 landing in "One Engine Inoperative" and "Stabilizer Trim Inoperative" scenarios.

In the crosswind scenario, let's assume your approach speed is 100 knots, and the crosswind is 20 knots. The crosswind is therefore 1/5 of the approach speed, and you need a larger crab angle to keep the airplane aligned with the runway. If you increase your approach speed to 120 knots, then the crosswind is only 1/6 of the approach speed, and the crab angle is smaller, making landing easier.


Does a constant speed prop maintain the optimal angle of attack at all time?

You may be overthinking it.  The governor will set the blade angle that provides the load on the engine that keeps it from speeding up or slowing down from the setting determined by the spring preload that resists the flyweights.  You could connect the governor to a big disc brake in place of the prop and it would work the same.
So it sets the blade AOA that gives the required load without knowing what that AOA is. It's just a spindle with weights, a spring to hold them in, a mechanism to preload the spring and an oil metering valve - there's no AOA feedback to the governor, only a speed feedback, and the input command from the pilot is just pushing on a spring.
Whatever blade AOA that is achieved is the blade AOA required to achieve the load on the engine.  Whether that blade AOA is 100% optimized to get the maximum thrust from that particular condition is another story, and blade twist, airfoil selection, blade length, number of blades, total blade area, and all that all have to be balanced against various objectives.
As to what particular aircraft speed, prop rpm and engine load gives the highest possible thrust efficiency from the propeller, you'd have to get from the prop designer and there may still be some optimization of all the parameters I mentioned toward a cruise case, or a static thrust case (like seaplane props; desirable to get on the step as quickly as possible), or a maximum speed case.


Why do aircraft leave the cruising altitude long before landing just to circle?

It's better to be low(-ish) and ready for a spot to open, than high and far from that spot. As to why, for busy international airports the answer is really simple:

► There isn't a way to manage it near perfectly (yet).

To understand that statement, requires some prerequisites, so I'll try to simplify and summarize the basics:

There is the concertina effect: it's when fast vehicles slow down, the spacing between them go down. So the nearer the airport for landing, the more squeezing happens.
Add to that that the arriving planes come from all or most directions, and the same low-ish airspace is being used by departures as well.
The trajectory of each plane depends on each plane's load and performance, and the wind it experiences. While wind is forecast, the forecasts aren't perfect.

A solution to that is for all planes to send their estimated trajectories to the air traffic management (ATM). That is one of the projects being worked on in Europe, but it's at least a decade from full deployment. One part of it is the extended arrival management (E-AMAN).

Why wasn't it worked on decades ago has to do with the history of data communication in aviation. And it boils down to money and return of investment. Initially some of the users, like the airlines, didn't see a benefit of the high cost of the high tech solutions they'd have to add to their planes.

Seasonal adverse weather en route or in the terminal area complicates matters even more.
Busy international airports with multiple runways land planes every 30 seconds or so, so you can imagine the impact of the slightest delay one plane headed to that airport experiences. So arrival management is first come, first served.

Related: What are the negative associations with Continuous Descent Approach?


Are there any preventive measures against bird strikes while in flight?

Airports engage in a number of strategies to reduce the number of birds nearby that might cause strikes. This has been addressed in a previous question: What are the ways to keep the birds away from airfields?

Avian Radar also exists:

  Avian radar[44] is an important tool for aiding in bird strike mitigation as part of overall safety management systems at civilian and military airfields. Properly designed and equipped avian radars can track thousands of birds simultaneously in real-time, night and day, through 360° of coverage, out to ranges of 10 km and beyond for flocks, updating every target's position (longitude, latitude, altitude), speed, heading, and size every 2–3 seconds. Data from these systems can be used to generate information products ranging from real-time threat alerts to historical analyses of bird activity patterns in both time and space.

https://en.wikipedia.org/wiki/Bird_strike#Flight_path

  Installations include civil applications at New York/John F Kennedy International Airport, Chicago/O'Hare International Airport and Seattle-Tacoma although the majority of both deployment and development activity is still focussed (sic) on military air movements.

https://www.skybrary.aero/index.php/Detection_of_Bird_Activity_Using_Radar

  MERLIN Avian Radar System technology...is used...to detect and monitor hazardous bird activity on and around airfields for bird-aircraft strike hazard management.

https://detect-inc.com/bird-control-radar-systems/


What should a pilot do when flying in the vicinity of parachute jumpers?

Qualification: I worked at a busy drop zone for 10 years.

Just announce yourself on the airfield frequency about 5-10 minutes out and they'll tell you what's going on, including which runway is active and how high they are jumping from - standard altitudes are 3000ft and 12,000ft AGL. At our place it was really simple: left-hand for 34, right-hand for 16. We landed everyone on the east side, and if we are dropping at 3000 all day you can just pop up to 4000 and be completely out of the way.

Under no circumstances make a cross-field pass as that's usually right in the middle of everyone else's landing pattern, and we don't carry radios.

If you are just passing by a 2km buffer is lots - no one is likely to be in the air that far away.

No reply usually means nothing in the air.


How do you repair a grounded aircraft at a remote location?

If you can, you'll fly in maintance yourself to get it fixed, perhaps by chartering a cargo plane on the way. If you can land the aircraft, you can probably get any spare part in through the same runway, with varying degrees of difficulty.

If it's bad, Boeing has an Aircraft On Ground team who should be able to fix pretty serious damage. Often, it may just be patched up until it's good enough to fly to get it to a place with better facilities.


Do windows on the side of the fuselage increase drag?

The long length of an airliner fuselage ensures turbulent flow at the station of the cabin windows, so their only contribution to friction drag are the gaps between metal and polycarbonate. The transition from a laminar to a turbulent boundary layer happens before the windows start. In Sighard Hoerner's classic Fluid Dynamic Drag we find in Chapter V these figures on the drag of surface imperfections:

The size of the gaps and the dynamic pressure at their location drives their drag contribution. Let's assume the windows are 0.4 m high, the grooves 2.5 mm (0.1") wide and shallow enough to have a drag coefficient of 0.008. Let's further assume we talk of a Boeing 747-200 with 100 such windows per side and restrict the drag calculation to the crossflow over the vertical part of the gaps. The full opening area of all gaps is $2\cdot100\cdot2\cdot0.4\cdot0.0025$ = 0.4 m² or 0.078% of the reference area of the 747. Wikipedia gives the parasitic drag coefficient of the Boeing 747 as 0.022, so the windows contribute one threethousandfivehundreth of that drag. Negligible, in other words.

But there is another source of drag: The windows are heavier than the metal which they replace, and to carry them around will increase induced drag. If we again assume 200 windows for a Boeing 747-200 at 7 kg each (these are from pre-polycarbonate times!), they weigh a total of 1.4 tons. This is 0.8% of its empty mass and equivalent to 12-14 passengers. To find the impact of this mass on a long-range flight over 6000 NM, we can use the Breguet equation; once with and once without the 1.4 tons of additional mass. The empty mass of the Boeing 747-200 plus 50 tons of payload is 228,100 kg, its L/D is 16, the specific fuel burn of its JT-9D-7 engines is $b_f$ = 0.0000184 kg/Ns and the cruise speed is Mach 0.84, which equates to $v$ = 250 m/s in FL 350:

$$m_1 = m_2\cdot e^{\frac{R\cdot g\cdot b_f}{v\cdot L/D}}$$

When we use $R$ = 11,112 km and run this once with landing masses $m_2$ = 228,100 kg and again with $m_2$ = 226,700 kg, the difference in $m_1$ is bigger by a factor of 1.65 (the take-off masses $m_1$ are 376,584 kg with and 374,237 kg without windows), so carrying the windows around costs the Boeing 747-200 911 kg of fuel or 0.61% of the total fuel mass per flight. This is one onehundredsixtythird of the total drag - still not much, but fourty times as much as the absolute contribution of the windows to friction drag (if we assume that the 747 flies at the polar point for optimum range).

This explains why conversions of airliners to freighters almost always replace the windows by metal plates but don't care that much about the gaps they leave. In the case of the 747 pictured below they are certainly big enough to be visible from afar.

A Japan Airlines Boeing 747 passenger-to-freighter conversion featuring aluminum window plugs. (Photo credit: Flickr)


Did Boeing need MCAS because the 737 MAX didn’t meet FAA longitudinal stability requirements, or was it to make the MAX feel like the NG?

The Boeing 737 MAX MCAS system is there ONLY to meet the FAA longitudinal stability requirements as specified in FAR Section 25.173, and in particular part (c) which mandates "stick force vs speed curve:, and also FAR Section 25.203 — "Stall characteristics".
FEDERAL AVIATION REGULATIONS Sec. 25.173 — Static longitudinal stability.

Sec. 25.173 — Static longitudinal stability.
Under the conditions specified in §25.175, the characteristics of the elevator control forces (including friction) must be as follows:
(a) A pull must be required to obtain and maintain speeds below the specified trim speed, and a push must be required to obtain and maintain speeds above the specified trim speed. This must be shown at any speed that can be obtained except speeds higher than the landing gear or wing flap operating limit speeds or V FC /M FC,whichever is appropriate, or lower than the minimum speed for steady unstalled flight.
(b) The airspeed must return to within 10 percent of the original trim speed for the climb, approach, and landing conditions specified in §25.175 (a), (c), and (d), and must return to within 7.5 percent of the original trim speed for the cruising condition specified in §25.175(b), when the control force is slowly released from any speed within the range specified in paragraph (a) of this section.
(c) The average gradient of the stable slope of the stick force versus speed curve may not be less than 1 pound for each 6 knots.
(d) Within the free return speed range specified in paragraph (b) of this section, it is permissible for the airplane, without control forces, to stabilize on speeds above or below the desired trim speeds if exceptional attention on the part of the pilot is not required to return to and maintain the desired trim speed and altitude.

FEDERAL AVIATION REGULATIONS Sec. 25.203 — Stall characteristics.

Sec. 25.203 — Stall characteristics.
(a) It must be possible to produce and to correct roll and yaw by unreversed use of the aileron and rudder controls, up to the time the airplane is stalled. No abnormal nose-up pitching may occur. The longitudinal control force must be positive up to and throughout the stall. In addition, it must be possible to promptly prevent stalling and to recover from a stall by normal use of the controls.
(b) For level wing stalls, the roll occurring between the stall and the completion of the recovery may not exceed approximately 20 degrees.
(c) For turning flight stalls, the action of the airplane after the stall may not be so violent or extreme as to make it difficult, with normal piloting skill, to effect a prompt recovery and to regain control of the airplane. The maximum bank angle that occurs during the recovery may not exceed—
(1) Approximately 60 degrees in the original direction of the turn, or 30 degrees in the opposite direction, for deceleration rates up to 1 knot per second; and
(2) Approximately 90 degrees in the original direction of the turn, or 60 degrees in the opposite direction, for deceleration rates in excess of 1 knot per second.

Here is some additional information: http://www.b737.org.uk/mcas.htm

MCAS is a longitudinal stability enhancement. It is not for stall prevention (although indirectly it helps) or to make the MAX handle like the NG (although it does); it was introduced to counteract the non-linear lift generated by the LEAP-1B engine nacelles at high AoA and give a steady increase in stick force as the stall is approached as required by regulation.
The LEAP engine nacelles are larger and had to be mounted slightly higher and further forward from the previous NG CFM56-7 engines to give the necessary ground clearance. This new location and larger size of nacelle cause the vortex flow off the nacelle body to produce lift at high AoA. As the nacelle is ahead of the C of G, this lift causes a slight pitch-up effect (ie a reducing stick force) which could lead the pilot to inadvertently pull the yoke further aft than intended bringing the aircraft closer towards the stall. This abnormal nose-up pitching is not allowable under 14CFR §25.203(a) "Stall characteristics". Several aerodynamic solutions were introduced such as revising the leading edge stall strip and modifying the leading edge vortilons but they were insufficient to pass regulation. MCAS was therefore introduced to give an automatic nose down stabilizer input during elevated AoA when flaps are up.


What techniques professional pilots use to keep their piloting skills sharp when not flying for an extended period?

Reading a lot is key; staying on top of your checklists too. I noticed I'm behind the airplane more depending on the complexity of the aircraft in question. I keep photocopies of my checklists at home to refresh my mind prior to a flight.

It should also be mentioned the value of sitting in your aircraft on the ground; it costs nothing, and you can take your time working through checklists and scenarios in your mind.


What is the relation between maximum airspeed and engine power?

In theory, yes. However, everything else isn't equal.

When you double the speed, you probably exceed the design parameters of the airframe. You'll definitely exceed the VNE of a 100mph airframe if you operate it at 200mph, and then all sorts of ugly things can start happening, from weird handling characteristics to large pieces, like the tail, coming off inflight. Remember that 4x drag means 4x the strain on the airframe. Is your airframe up to the task?

Most 100mph aircraft have a design optimized for short takeoff and landing, wings that are very efficient at slow speed, but not efficient at higher speeds. So the simple drag calculation may not hold true, when you take wings designed for slow speed and operate them at a much higher speed. The actual drag will probably be higher, if you consider the design of the airframe.

Compare a 100mph aircraft, say a Cessna 150, to a Mooney 201, that can go 200mph. The Mooney has much thinner wings, that result in a high landing speed, but lower drag at higher speeds, while the 150 has a fatter wing that gives a lower landing speed and better low speed handling, but may not fare so well at a much higher speed than it was designed to handle. The other tradeoff, aside from speed, is the 150 is far more forgiving of a clumsy pilot, while the Mooney is probably not the best trainer for first time students.

Note that the Cessna goes 100mph on 100hp, while the Mooney goes 200mph on 200hp, so the advantages of designing for the target speed can be seen in not just upping the power, but redesigning the airframe (and adding retractable gear).


Did I identify these aircraft correctly?

Looks like it :)

Double window exits over the wings, so no A321 or A319 (with a few exceptions such as Easyjet's A319)


How does ATC handle changing QNH/altimeter values?

In the US, ATC simply broadcasts a notification on whatever frequency is needed. For the terminal environment, section 2-9-2 of the ATC orders says:

  Broadcast on all appropriate frequencies to advise aircraft of a
  change in the ATIS code/message.

The phraseology is usually something like this:

  Attention all aircraft, Bowman information Kilo is now current.

For en route operations (see section 2-7-2) the ARTCC gives altimeter setting updates directly:

  Attention all aircraft, the Nashville altimeter now 2992


Finding the center of gravity/centroid of an airfoil?

In addition to checking out wing frame structures on the internet, why not go down to the hobby shop and get a balsa plane kit?  Airplane building is a hobby you will have all your life.

Generally, in balsa, you have a top and bottom spar, a leading edge, and a trailing edge to attach the aileron (get lots of sand paper and CA glue).  As mentioned, put you spars at around 25 - 33 % from leading edge, around the highest part of the rib.  You may also have good luck strengthening your wing by covering it with 1/16 sheet balsa, others use heat shrink monocoat.  But you must also stiffen the wing so it can not twist when you use the ailerons.  So you may wish to add balsa between the ribs connecting the top and bottom spars, creating a box structure.

A lot of ways here, and you can't read too much about it.  Please let us know how you are doing with it.  Check out RC Groups website as well.


FIR stands for Flight Information Region.  There is lots of information about these on-line, to the point that it isn't worth regurgitating it here.

However, the FIR should be the least of your concerns at this stage of your training...

If you want to fly "in and among the mountains" of the extremely rugged North Cascades, I would strongly recommend you get your Private Pilot Certificate first, then take a mountain flying course as a minimum before you get any lower than 1000' above the highest peak in a sector, and/or gliding distance from a wide flat valley floor with suitable emergency landing spots.

Narrow valleys and downdrafts on the lee side of ridges are killers.

I live up here in Washington state and have flown in the mountains for years, but they are no place for a beginner on a student solo.  Especially this time of year.


Why can't armrests be raised on window and aisle seats?

Apparently, it can be done, atleast in some aircraft; even in those cases, the armrests are locked, unless one knows the location of the release button.

As for why, it seems that there is a possibility that the upright armrests can be an obstacle (for people in the next seat row) and FAA expects the cabin crew to ensure that the armrests are in forward condition prior to takeoff/landing. According to FAA Volume 3, Chapter 33, Section 3 Instrument and Equipment Requirements,

  Inspection of the Hardman Model 9500 and other passenger seats installed on several aircraft, disclosed that the armrest in the upright or stowed position can protrude approximately 45 degrees aft the seat back. In the event of an emergency evacuation, protruding armrests could present an obstacle between seat passageways, obstructing emergency exit access. Air Carriers should emphasize to F/As that prior to takeoff and landing they verify that the armrests are in the normal forward/down position in order to ensure that they do not obstruct the passageway between the row of seats leading from the aisle to the emergency exit.

As this is a problem in aisle seats (armrests in middle seats cannot go back usually), they have to be fixed forward or atleast locked in position. This is the reason for them to be locked in case of aisle seats. As for window seats, the sets are usually made in a row and you don't really know if the seat will end up in window or aisle i.e. whether the row will get fixed on left or right (or middle, in widebodies). Net result is that both the ends of the row are fixed just to be sure. In other words, the windows armrest is a collateral damage.


What benefit is provided by an MCA that is not already provided by an MEA?

MCA is for the fix and specifies the minimal altitude at which a normal climb can clear all obstacles.

MEA is the for between fixes and assures acceptable navigation signal coverage.

source wikipedia.

The MCA can be lower than the MEA of the adjoining route so MEA is required so you won't crash into the next mountain and MEA can also be lower than MCA so it's required so that the pilot can know to climb before reaching the fix so he knows he can get over the next obstacle safely without needing to circle or zigzag to buy time for the climb.


What is an approved weather source for flying an instrument approach into an airport with no working ATIS?

How is the ADS-b weather derived? If the ATIS is inop, it will usually be because the sensor equipment is inop. If that is the case, how would ADS-b get the data for that airfield? If the sensors are working and the transmitter is inop, you would get the weather directly from ATC. If you were in IMC and/or IFR, your Approach plate would list an alternate source of weather info, and/or minimums adjustments when the weather is not available.

Saying that, having the weather is not a requirement to land at a Class G or E airport in VMC. Most airports will revert to one of these when the tower closes. A pressure sensitive altimeter is not necessary in VMC. Title 14 CFR, Part 91.205(b) just says “Altimeter”.

In all other cases, follow the regs below:

  91.121 Altimeter settings
  (a) Each person operating an aircraft shall maintain the cruising altitude or flight level of that aircraft, as the case may be, by reference to an altimeter that is set, when operating—
  (1) Below 18,000 feet MSL, to—
  (i) The current reported altimeter setting of a station along the route and within 100 nautical miles of the aircraft;
  (ii) If there is no station within the area prescribed in paragraph (a)(1)(i) of this section, the current reported altimeter setting of an appropriate available station; or
  (iii) In the case of an aircraft not equipped with a radio, the elevation of the departure airport or an appropriate altimeter setting available before departure; or.
  (2) At or above 18,000 feet MSL, to 29.92” Hg.


Trying to find the vertical acceleration by subtracting weight from lift

Your math looks right to me. If an airplane has the statistics that you listed there, then it will accelerate upwards at $16.48\ \mathrm{m}/\mathrm{s}^2$, as you calculated. The occupants will experience about 3 g's of proper acceleration (1 g from gravity, and about 2 g's from the acceleration).

But here's what would actually happen, in context.

To start, assume that the plane is in straight and level flight at 33 m/s. (Here's why I'm making this assumption: You're subtracting weight from lift, which only makes sense if the lift vector is pointing straight up. And if the lift vector is pointing straight up, then the plane is probably in straight and level flight.)

While the plane is in straight and level flight, the lift must equal the weight, so the coefficient of lift must be much less than the 1.5 you have here.

Then, the pilot suddenly pulls back on the yoke, causing the plane to pitch up. This causes the angle of attack to quickly increase, which causes the coefficient of lift to increase to 1.5. The plane starts accelerating upwards at $16.48\ \mathrm{m}/\mathrm{s}^2$.

At this point, let's assume that the pilot maintains a constant pitch after this initial pull-up.

As the plane's vertical speed increases, its climb angle also increases, which causes the angle of attack to decrease. This, in turn, causes the coefficient of lift to decrease again, until the lift and weight approximately balance out again. At this point, the plane is in a steady climb. The vertical acceleration is now $0\ \mathrm{m}/\mathrm{s}^2$, and the occupants are feeling just 1 g again.

(I'm making a couple of small simplifying assumptions in the above: I'm assuming that there is no updraft or downdraft, and that plane's engine is not producing a significant amount of upward force.)


How (and when) to use the BFO button on an ADF?

Let me try to explain this from the radio perspective.

In a regular AM transmission (A3E emission type), you have a carrier and two side-bands. The usual receivers use the carrier to demodulate the audio information in the sidebands. The spectrum looks something like this:

Note: Horizontal axis is frequency, vertical axis is amplitude.

In real-life, it would look something like this:

Note: Vertical axis is time, with present being a the bottom, horizontal axis is frequency, increasing from left towards right and amplitude is encoded in color, with dark blue/black being low amplitude and white being high amplitude.

The two sidebands are the wavy-looking structures to the left and right and they carry the audio information. The carrier is in the middle and can be seen as the bright white line, especially visible during moments of silence.

When we want to send let's say Morse Code telegraphy over AM, we get the A2A emission type: Carrier and two sidebands, each carrying Morse code data.

Or in real-life something like this:

Here, we can also see the bright white carrier and the Morse code in the sidebands, with lower being a bit weaker than the upper.
Now, our AM receiver doesn't really know what's in the sidebands, the audio just goes to the speaker. So no special adjustments are needed to use a AM receiver for A2A emissions.

OK, so what does this have to do with BFO? Well, BFO is needed when we want to receive carrier-less data using regular AM receiver.

Let's now take a look at the spectrum of a A1A signal:

Or in real-life something like this:

There isn't much to see, only the "carrier". However, if we take a look at a real-life recording of the spectrum, we'll see that the carrier is being turned on and off, with no sidebands.

Now, when we input that to our AM receiver, we won't hear the Morse code. Depending on the receiver type, there might be an audible lack of noise when the carrier is on, but the expected tone is not there, since the sidebands are empty.

The BFO (Beat-Frequency Oscillator) helps us there. It artificially re-inserts the carrier, so combination of the re-inserted carrier and the A1A signal reach the receiver. The receiver thinks it's hearing a regular A2A or A3E signal and just outputs the received Morse Code tone. On the spectrum, we see something like this:

So the answer would be to use the BFO with A1A NDBs and not to use it with the A2A NDBs.

Possibly useful extras:

Why the name BFO?
When two sinusoidal signals, with frequencies A and B are mixed together, the result is a pair of new signals with frequencies A+B and A-B. This phenomenon is called Beating. In case of radio, if the signals are close together, the difference can drop down into the audio spectrum. For example, beating of 353 kHz signal with 352 kHz signal will result (among other things), in a 1 kHz signal, which we can output to a speaker.

A3E/A2A power and spectrum efficiency:
The carrier and one sideband do not participate in the actual transmission of information and are therefore wasted power. Newer systems try to avoid using them, when possible, also saving space in the spectrum. However, the carrier simplifies receiver design.

A2A variants:
Depending on the region, the A2A beacons might have the carrier on all the time, as shown above, or might key the carrier as well as the sidebands. Furthermore, some might only have one sideband, and save some power through that. Regular AM receivers can receive signal with a carrier and only one sideband. This is called Compatible Sideband.

J3E and BFO:
J3E, aka Single Side Band is a refinement of AM which is mostly used on high-frequency bands. It eliminates the power wasted in the transmission of the AM carrier and the other sideband and also uses less spectrum space, which is in shortage on the high-frequency band. On the other hand  the receiver and transmitter are more complicated. In aviation, the upper sideband is currently used. An AM receiver with BFO can be also used to receive J3E transmissions. Here's a spectrum of that:

A2A and BFO:
Not  coming from the aviation field, I don't know how the exact settings on the instruments work, so some of these might not apply due to precise offsets and audio filtering, but in general, if you re-insert the carrier on an A2A system, one of the following will happen:
The reinserted carrier frequency matches the original carrier. In this case, you won't hear any difference.
The reinserted carrier has a slight offset from the original carrier. In this case, beating will occur. You should hear the Morse code identification properly, but you might also hear a low-frequency sound in the background, if the system is capable of reproducing it.
The reinserted carrier has significant offset from the original carrier. In this case, you'll be able to hear both the original carrier and the Morse code identification. Note that the audio frequencies might be shifted in unusual ways, depending on where exactly the reinserted carrier was actually reinserted.


How does the B777 Side brace locking mechanism work?

The scissors struts on that gear physically lock in alignment instead of over centering.  The inboard strut extends into the outer one a short distance, which is forked to accommodate it.  The little actuator with the lever and springs is the downlock mechanism.  The downlock will have some sort of pawl or plunger interface hidden inside that forked interface, roughly where the downlock safety pin is, that engages to lock the inner strut and outer strut together so they are like a one-piece strut.
The actuator pulls in to disengage the mechanical lock, and the springs provide a counter pressure against the actuator to provide a passive "engage" force the rest of the time.  The springs aren't maintaining an over-center condition, only applying pressure to a mechanical lock.
In this video you can see that the downlock release actuator appears to also pull the links out of alignment once the release lever it operates is fully released, and if you watch full screen you can make out the locking mechanism as the struts fold, although the precise details of that mechanism would require access to a 777 maintenance manual.


Why don't modern fighter aircraft hide their engine exhaust?

There are a few which do (none of them in production, though) and the reason is the added weight and restrictions in varying nozzle geometry for best efficiency.
The tail arrangement of the F-4 is the result of its heritage. Early McDonnell jets all had the fuselage extended past the engine exhaust in order to shift the engine mass forward, near the wings, so the internal ducting could be as short as possible while the long fuselage held the large amount of fuel required for their initial design as long-range escort fighters. Originally the engines were placed in the wing roots (F2H Banshee) and moved into the fuselage as wings became smaller and thinner while engines grew in size.
Compare the XF-88, the F3H of the Navy, the F-101 Voodoo and the F-110, later to be renamed F-4, and the similarity should be obvious. Other manufacturers like Northrop with their the F-89 Scorpion used the same layout. Like all earlier models, the initial designs of the F4H (the F-4 in the old Navy designation system) used a straight tail. To be fair, at this time IR guided missiles were in their infancy and a low IR signature was not part of the requirements.

XF4H-1 wooden model (picture source)
The later addition of dihedral to the outer wings and anhedral to the tail was for aerodynamic reasons, not to improve IR signature.
NASA's history pages report that

the […] high position of the horizontal tail in combination with the wing-shape parameters led to undesirable nonlinear pitching-moment characteristics at high angles of attack. The large anhedral angle, or droop, of the horizontal-tail surfaces greatly improved the pitching-moment characteristics, as well as increasing directional stability. To achieve the proper balance in dihedral effect for the integrated aircraft configuration, however, a large positive dihedral angle was incorporated in the outer panels of the wing. In addition, the wing dihedral elevated the wingtip vortexes relative to the horizontal tail and further improved the pitching-moment characteristics of the aircraft.

The biggest threat using IR targeting are small, shoulder-launched missiles which target the airplane from below. The F-4 engine and tail arrangement will do nothing to hide its IR signature from them. There are modern fighter designs which hide their IR exhaust, and they place the exhaust on the upper rear fuselage for the reason outlined above.

Top view of the Northrop XF-23 (picture source). However, using a rectangular duct for high-pressure flow requires much more mass than a round duct. Also, optimizing this duct for afterburner operation and thrust vectoring is much harder than with a round duct right at the end of the fuselage.


Why don’t airliners use stabilizer movement to assist with large pitch control inputs?

The elevators hydraulic actuators are quick response devices, the THS is screw operated and therefore is slower to response.
Therefore it’s normal to use the elevators for short term action and theTHS for long term action.

For safety you can’t rely only on elevators or only on THS. One system should be able to neutralize the other in case of failure.


How do ratings work with pilot certificates?

This answer applies to adding a new aircraft category onto your existing Commercial Pilot Certificate in the United States.  Consult the standards of your country's governing body for aeronautics if attempting to do this outside of the USA.

To address the second paragraph, once you hold a Commercial Pilot Certificate for the same category and class of aircraft as your private certificate, you are considered to hold a Commercial Pilot Certificate only.

In regards to the third paragraph, yes additional training will be required to fulfill the requirement of 61.63 (b) for the addition of an aircraft category rating to your CPL.  You will be required to meet the aeronautical experience requirements listed in 61.129 (c) and receive an endorsement in your logbook to take the practical exam in order to add a helicopter category to your CPL.  You will not be required to take the commercial pilot knowledge test again per 61.63 (b).


What configuration of autothrottle is required when pilots are landing an Airbus?

Do Airbus pilots normally disengage the Auto Throttle on a manual landing ?

Depends on what you mean.

During the initial part of the approach, no, they do not deactivate the autothrust (not autothrottle, in this case):

But the autothrust is not designed for landing and just before touchdown there is an automatic callout in the cockpit: Retard. Retard. (it can be heard in this video 4 times).

The callout is needed because of the A/THR inner working: while in SPEED mode it can apply any throttle between 0 and the current throttle lever position; i.e., if for example the throttle is at the 80% setting, the autothrust can apply any throttle between 0% and 80% (based on the required airspeed). At the Retard callout the pilots will move the levers to the IDLE position, effectively deactivating the autothrust:


Do turbo prop airliners generate thrust using the propeller and compressed air or just the propeller?

Turboprop engines transfer almost all of the turbine's rotational energy to the propeller, though there is some waste in heat and exhaust gas as in all engines. The exhaust does not form any major amount of thrust unlike in other turbine engines ("jet engines", like a turbofan or turbojet). Turboprops are more efficient than other "jet engines" at lower altitudes due to the thickness of the air at lower altitudes whereas jets are more efficient at higher altitudes, though turboprop pilots will tell you they fly a jet, being that a turboprop is still a turbine engine, aka a jet. :-)


What’s the speed for lowest sink rate on a DA20?

Admittedly, my prop performance theory is a tad rusty, so maybe someone else can provide proof here.

I seem to recall that - assuming a quadratic drag polar which might not hold true for your aircraft - minimum sink speed has a theoretical value of .76 x best glide speed, so in your case that would be around 56 KIAS.

If you’re comfortable and consider it safe to do so, why don’t you (at a safe training altitude) trim for 73 KIAS and establish a stable idle descent, note vertical speed descending through a predetermined altitude, reposition to initial altitude and repeat in maybe 5kts decrements down to stall speed or some safe margin above - the former of course only if flying right down to stall is still trained and allowed in small aircraft. This will give you at least a rough idea of where minimum sink speed lies and what rates to expect.

The DA 20 Approved Flight Manual doesn’t help much, by the way.


Why doesn't EVA Air BR087 (Taipei to Paris) follow the shortest path?

EVA Air is Taiwanese. Taiwan and People's Republic of China are not on the best of terms (publicly).

  The relations between China and Taiwan have been characterized by limited contact, tensions, and instability, due to the fact that the Civil War merely stopped without formal signing of any peace treaty and the two sides are technically still in a state of war.

The details of the bilateral Air Service Agreements (ASA's) are not public though. Treating airlines differently is supported by a discussion on airliners.net.

EVA Air does land in Mainland China, but that's only recently. That's because ASA's are not black and white. (Both economies have been on good terms lately.) An example of the limited liberalization:

  The first direct commercial flights from China (from Guangzhou) to Taiwan since 1949 arrived in Taipei on January 29, 2005.

About 70% of the Chinese airspace is military controlled, i.e., the military may choose to allow KLM, but not EVA Air.

  Aviation experts agree that one of the main problems in China is the fact the country’s airspace is largely controlled by the military, leaving little room for civilian aircraft even as the domestic airline industry booms. According to the state-run China Daily newspaper, less than 30% of China’s airspace can be used by commercial airlines, compared to about 80% of the airspace in the United States (BBC, April 2016).

As DeltaLima mentioned, KLM operates a subsidiary on those routes, KLM Asia:

  A wholly KLM-owned subsidiary registered in Taiwan was established in 1995 to operate flights to Taipei without compromising the traffic rights held by KLM for destinations in the People's Republic of China.

Here is another example a couple of hours apart (do note China Airlines is Taiwanese).

(flightaware.com)


Has the FAA banned FPV for model aviation?

The FAA has interpreted the rules to mean that the operator must have a line-of-sight view of the model aircraft at all times, and that FPV does not qualify.

  Based on the plain language of the statute, the FAA interprets this
  requirement to mean that: (1) the aircraft must be visible at all
  times to the operator; (2) that the operator must use his or her own
  natural vision (which includes vision corrected by standard eyeglasses
  or contact lenses) to observe the aircraft; and (3) people other than
  the operator may not be used in lieu of the operator for maintaining
  visual line of sight.

But also note that this does not apply if:

  ...the aircraft is operated in accordance with a community-based set of
  safety guidelines and within the programming of a nationwide
  community-based organization;

The above is from the linked NPRM released in June 2014. The latest NPRM from February 2015 has the same requirements.

So members of an organization like AMA are exempt from that rule. The AMA requires a spotter to be used when flying FPV.


Radar mounting bulkhead: this is the vertical plate to which the radar antenna is attached. This is just a structure.
Strobe light/anti-collision beacon: this is a bright light that flashes to make the aircraft more visible and prevent collisions.
Engine bleed-air primary heat exchanger: this is a heat exchanger for bleed air from the engine. Bleed air from the engine is hot and needs to be cooled down for various applications, this cooling down is done in the heat exchanger.

It's quite easy these days to find out what an unknown term means. Just go to Wikipedia and enter the unknown term into the search box.


Why is a feather check performed on a piston engine and how much RPM drop should be allowed?

The check is performed to make sure the prop will actually feather when pulled past the feather gates.  You'll be in a world of hurt if you are not able to feather a prop if the engine quits.

A couple hundeed RPM drop is acceptable (generally).  So called "deep cycling" props does nothing for you.  I suppose that there are some goofy mechanisms on oddball planes that require a deep cycle but the vast majority only require you to observe a small drop.

Remember, you are checking that the governor can control the prop, not how far the prop can travel.

Edit 1: I should add that you should just do whatever the POH/AFM tells you to do.

Edit 2: a pilot is typically looking for an oil pressure change, manifold pressure rise, and an RPM drop with each prop cycle.


What aircraft is this flying near Greenford?

Spy planes!!! Looks like I found an answer after two years when I came across a blog called 'secret bases'.

"Keen MI5 spy plane spotters should continue to lurk around RAF Northolt. A company formed by former elite RAF pilots, 2 Excel Aviation, actually based at Sywell Aerodrome, Northamptonshire, is now performing those spooky Northolt tasks, as part of its Scimitar special projects team.

They are using Piper PA31 Navajo aircraft "G-SCIR" (ModeS 40729C), "G-SCTR" (ModeS 40029D) and "G-SCMR" (ModeS 40729E) — all registered to 2 Excel in February / March 2017. They joined regular "sneaky-beaky" craft "G-UMMI" (ModeS 400C86) which is regularly spotted with special communications equipment attachments.

All three RAF Northolt Piper Navajo PA31 craft had been purchased by 2 Excel from Mike Jones Aircraft Sales Inc in Murfreesboro, Tennessee, America, who specialise in Colemill Panther conversions for performance and safety boosts. G-SCTR previously carried registration mark N331DB. G-SCIR had been supplied with tail number N522AW and G-SCMR had previously carried N27773.

Military aviation enthusiast Alan Warnes blogged on the subject in August 2017 on his Warnesy's World website, but strangely he only noted two out of the three Piper Navajos and missed G-SCIR. Curious, as the three registrations all took place at the same time – February / March 2017.

The London Evening Standard's Business Pages reported on my findings in an article headlined "Lift Off: Home Office privatises MI5 spy plane operations"."


The APU is an alternate source of electrical power and also bleed air.  Since it doesn't have any function to generate thrust, it burns considerably less fuel than the engines do, and is intended primarily for ground use, although most APU's can also be operated in flight for things like a second source of electrical power if an engine generator has failed, or a source of bleed air if the bleeds are closed on the engines in order to generate more thrust.

In that diagram, what you're seeing is a portion of the pneumatic system, showing that the bleed air from the APU can be routed to both air conditioning packs (on many aircraft the APU can power both AC packs on the ground; on some aircraft it can only power one at a time), as well as to the engines, where it provides air for starting them.

On some aircraft, the bleed air from the APU can do other things, like pressurizing the water supply, and while it isn't operationally useful, it can generally supply bleed air into the anti-ice ducting for the leading edges.  In practice, though, that's only done when the engines are running, due to the greater volume (and temperature) of hot bleed air that the engines can produce compared to the APU.


How does the landing gear damp vibrations?

By having a spring element and a damping element - some small planes use use leaf or tubular legs bending to act as springs, other use rubber bungy cords, others use, like bigger aircraft commonly do, a gas strut damped by liquid viscosity. The damping in the puddle jumpers is the scrub of the tyres moving laterally on the runway as the suspension moves up and down. Shimmy damping in the nose gears can be either by elements providing viscous damping or coulomb/friction damping.


Some TMA arrival sectors can be further split up into an arrival/pickup part and a director/feeder part.
The arrival controller is responsible for getting aircraft separated either onto downwinds or onto transitions, where they are handed off to the director. The director is then only responsible for turning these aircraft onto the approach, in most cases the ILS.
Essentially, the arrival or pickup tries to get everyone onto the correct separation and speeds, so the director or feeder can turn and clear the aircraft onto their approaches, i.e. feeding the ILS with aircraft.

(Source: SentryRaven - Own Work)
The above picture shows the TMA airspace of Frankfurt (EDDF). The TMA arrival controller would clear aircraft onto the transition or a vectored downwind and hand them over to director.
The director position would then vector the aircraft onto the ILS for a handoff to tower.


Is the pilot required to keep visual lookout during IFR operations in VMC?

You didn't mention which country or jurisdiction you're asking about, but in the US 14 CFR 91.113(b) says:

  When weather conditions permit, regardless of whether an operation is
  conducted under instrument flight rules or visual flight rules,
  vigilance shall be maintained by each person operating an aircraft so
  as to see and avoid other aircraft

I assume other countries have similar regulations but even if they don't, it's still common sense and good piloting to keep a visual lookout whenever possible.


Why are aircraft callsigns pronounced over the radio in a non-phonetic alphabet way?

The FAA's ATC orders (section 2-4-20) say that the 'group form' should be used by controllers when talking to any aircraft with an FAA authorized call sign. So you would expect to hear it with airline traffic but not private flights:

  Air carrier and other civil aircraft having FAA authorized call signs. State the call sign followed by the flight number in group
  form.

  NOTE- “Group form” is the pronunciation of a series of numbers
  as the whole number, or pairs of numbers they represent rather than
  pronouncing each separate digit. The use of group form may, however,
  be negated by four-digit identifiers or the placement of zeros in the
  identifier.

  EXAMPLE− “American Fifty−Two.” “Delta One Hundred.” “Eastern
  Metro One Ten.” “General Motors Thirty Fifteen.” “United One Zero
  One.” “Delta Zero One Zero.” “TWA Ten Zero Four.”


Since this an FAA instrument approach procedure, this answer is specific to the FAA.

The RADAR label indicates that these fixes are marked on the approach controller's screen and he/she can advise the pilot when the aircraft is over the fix.

The use of Radar for arrivals and approaches is outlined in FAA JO 7110.65, Chapter 5, Sections 9 and 10. FAA Order 8260.19, paragraph 8-2-5(a) states that "Radar vectoring may be provided through any approach segment up to and including the final approach fix."

You'll note that the approach plate does NOT indicate RADAR REQUIRED because it is not the only method of determining or defining the fixes. In this particular approach, arrival at a fix can be determined THREE different ways: with Radar, LOC with DME (or GPS lieu of DME), and LOC with VOR radial. Per 8260.19, paragraph 8-6-6h, all IFR aircraft are assumed to have at least one VOR receiver, thus no equipment requirement note is required for this particular approach.

In practice, I've found that ATC will not call out crossing a fix unless you specifically request the service, though they will usually identify your position prior to hand-off (e.g. November 1234, two miles from SHAGY, contact tower on 120.5).


Where can I take ICAO Aviation English proficiency test?

ICAO does not offer testing or training itself, only sets standards that most countries adopt (sometimes requiring stricter even) as their own.

The relevant aviation authorities in your country might have such a list of places authorised to offer the test, if you can't contact them directly any flight school will be able to assist either directly or by bringing you into contact with another school that offers theory classes.

E.g. in the Netherlands EASA rules apply, which sit on top of ICAO rules, and are enforced by the Dutch ministry of transportation. Examination is handled by the CBR (which also handles drivers' licenses). Schools offering theory classes can enroll you in the exams and tend to have the facilities to take the exams (which are all remote/computer based these days, in the past you had to make your way to one of a very small number of offices on a limited number of available exam days each year).

Similar arrangements are to be expected in other countries.


What are the design parameters for airliner safety?

Extremely improbable is defined as 10$^{-9}$ per flight hour, or one in a billion flight hours. For instance, from EASA CS-25 Detail Design Requirements 4.3:

  The actuation system minimum requirements should also be continuously met after any combination of failures not shown to be extremely improbable (occurrence less than 10$^{-9}$ per flight hour).

For aircraft systems and structures, that means we need to consider the following:

What is the probability that failure of function causes a catastrophe?
What is the exposure time to the failure condition?
What is the failure rate of the hardware?

Flight control systems are flight critical: without it functioning, we may assume that a catastrophe will occur. NASA-TM-72860 depicts the accumulated failure analysis factors for flight control systems like this:

If we take the cruise autopilot as an example:

When it fails, it just means that the pilot will hand-fly the aircraft, and the probability of its failure causing a catastrophe is set to one in a million flying hours. Pretty remote.
During cruise, the autopilot is on all the time. Exposure is pretty close to 100% (= 1)
That requires the cruise autopilot system to have a reliability of 1 failure per thousand flying hours.

The reliability demand is for system functionality, including sensors, processors, electronics, power supply etc. One way to meet functionality demand is to duplicate the system, so that if one system fails, one or more remaining systems will still carry out the function. Not really necessary for the cruise autopilot 10$^{-3}$ demand, but for instance the auto land system must be 1000 times more reliable: it is only functional during landing, but the probability of function loss causing a catastrophe during landing can be quite high due to proximity of the ground and very short reaction times.

That is why the CAT III auto land systems are up to triple redundant - the complete system is duplicated three times - if we only need one functional system and we have three, the functionality failure rate is $f(sys)^3$ Each individual system can then have a failure rate of 10$^{-2}$ per flight hour.

To put these numbers into perspective: the average B777 now flies 12 hours per day, that is 4,380 hours per year. It would have to fly for 228,000 years in order to experience a catastrophic failure with a chance of 1 per 10$^{-9}$ flying hours.

EDIT

Some very good questions from the comments. I'm answering them here, since all comments may be removed once the tally is 20 or more.

@Michael But how are those probabilities determined? Verification through testing gets harder with increasing safety: in order to get any statistical relevance, one would have to subject a safety critical system to 10 billion operational hours and track if there are indeed 10 functional failures. Operational records of all aircraft throughout history provide a frame of reference. Most design changes in aircraft are incremental for this reason, build up operational history of the aircraft first. Design parameter restrictions for military aircraft are much lower, and that is where most revolutionary design changes come from.

@James S:It appears all of these p(Catastrophes) are in isolation. Is there any attempt to calculate chance of catastrophe when there are multiple failures, or chance of failure when one item has already failed?
Yes:

Common mode failures, for instance EMD after an atomic blast that stops all electronics from functioning.
Hidden failures from back-up systems, or systems not in use at the moment. Redundancy is always better because it is always known that the system is operating.
Cascade failures, where one blade tears through all three hydraulic systems.

All of these failure modes may not result in more than 10$^{-9}$ per flight hour. For instance the Gust Load Alleviation: it is only required during an actual gust, but the status of the system since the last test or operation is unknown. Therefore the system reliability used in these failure calculations will have to include all possible failures since the last time the equipment was tested.

@Michael Kjörling Wikipedia claims that 1,526 Boeing 777 aircraft (all models) have been delivered. ... There have been six hull losses, minus one due to criminal act, or one non-criminal hull loss per about 31 million (about 10^7.5) flight hours. The estimates seem to be off by at least one order of magnitude. A hull loss without multiple deaths is not defined as a catastrophe. The design parameters only account for systems functionality and structural integrity, not acts of war. ...error conditions arising from system failures which did not result in a hull loss. are not defined as catastrophic, if a procedural change can fix the situation then the reliability requirements are less strict. The 10$^{-9}$ is a lower limit design parameter: for the B-777 case, divide the actual catastrophes as defined by authorities by the actual flying hours of the fleet, and it becomes apparent how excellent the safety numbers are. But they only start to gain statistical accuracy now, up to 5 - 10 billion flying hours accidents could all be flukes.

Then again: multiple similar catastrophic failures of a new fleet within a short time period may not be coincidental.


How do modern turboprops avoid slow spool up of early jets?

Two ways:

As Dave pointed out above turbopropeller engine cores, like all aviation gas turbines, do have a spool up lag.  This is mitigated a couple of ways.

In a free turbine turbopropeller engine, the gas core spool is independent of the power turbine, allowing it to spin up much faster, and subsequently increase the amount of power delivered to the power turbine much faster.

In direct drive turbopropeller or turboshaft engines, the engine - and the propeller - operate at a near constant speed with increase or decrease in power provided by altering fuel flow and adjusting propeller pitch for the load.  Direct drive engines like the Garrett TPE-331 have a near instantaneous power response to power lever commands.  The downside to these designs are that they can be extremely treacherous in the event of an engine failure without an autofeather system linked to a negative torque sensor.  They are also very noisy on the ground.


Do (or can) pilots observe religious fasts when flying?

There is no general answer for this question. Do pilots observe religious fasts during flying? Some do, as this article notes:

... although Islam gave permission or leeway to break fast if one found it tiring during the flight, most pilots and cabin crew still chose to fast.
“So, I fasted for 10 hours 50 minutes, compared to 13 hours 42 minutes in Kuala Lumpur and 11 hours 11 minutes in Melbourne. Much shorter time than fasting in Melbourne, isn’t that interesting?
“However, on June 29, 2016, I will be flying to Jeddah. Jeddah residents will be fasting for 14 hours, 54 minutes while KL residents will fast for 13 hours 43 minutes. I will probably have to fast for 17 hours! This is when I have to be really patient. I may break my fast once I have landed.
For the safety of passengers and to ensure a smooth flight, if both pilots are Muslims, they take turns to eat, he said.

However, there is no way to tell for certain how many aircrew observe religious fasting, as this pilot may be talking about that particular airline, for example.
As for Can they observe religious fasting, it depends on the regulation and company policies. Most of the civil aviation authorities don't have anything specifically related to religious fasting, preferring to cover them under fitness for duty, though there is atleast one case where the regulatory authority explicitly forbid fasting.

Indonesia’s Directorate General of Civil Aviation ruled that all safety-sensitive aviation personnel must eat while on duty during Ramadan, the Islamic month of fasting


What airplane is this? and why the strange inlets?

That's a Polish Air Force MiG-29 "Fulcrum".  The strange intakes are to decrease the risk of foreign object damage during rough-field operations.

Edit to clarify: Normally, when the MiG-29 is in flight, the large ramp intakes below the wings are open, providing all the air for the engines, and the louvered intakes on top of the wings are closed.  However, if the aircraft is going to be operating from rough fields or flying at very low altitude, the pilot can close the main air intakes.  When the main intakes are closed, the louvered auxiliary intakes automatically pop open, so that the air going into the MiG-29's engines comes from above the aircraft, rather than below it; this greatly decreases the risk of the engine eating loose objects on the runway (that, and the fact that the opening a foreign object would have to pass through to enter the engine via an auxiliary intake is much smaller than the opening for the main intakes).  As the auxiliary intakes are smaller and at an angle to the airstream, the engines can't get as much air (and, consequently, can't produce as much thrust) when using the louvers as they can when using the main ramps; Mikoyan apparently decided that, for rough-field operations, decreased performance was an acceptable price to pay for a decreased rate of engine object ingestion.


Why don't we fly helicopters with yokes?

Well first off, a helicopter doesn't have either a yoke or a stick; it has a cyclic.

Second, the original use for a yoke or a stick was to provide a pilot with a mechanical advantage in actuating the airplane's control surfaces against the force of the relative wind.  Helicopters never needed this as the cyclic actuated the swash plate on the rotor mast, changing the pitch of the rotor blades as they passed over.

Third, helicopters demand a little more 'hands on' attention when flying them as opposed to airplanes.  The helicopter pilot is required, particularly in hovering, to make constant adjustments to the cyclic, collective, throttle (if not equipped with a governor) and anti-torque pedals.  Therefore a yoke style cyclic is not useful to a helicopter pilot.

A cyclic does not necessarily need to take the form of a traditional joystick as in the example from an MD900 (Top) and an R22 (bottom).


Does anyone have a diagram of the HC-130J wing dimensions and fuel tank locations?

If you're looking for the technical data, i recommend you the "service news" material, that can be checked out here: https://www.lockheedmartin.com/content/dam/lockheed-martin/aero/documents/sustainment/csc/service-news/sn-mag-v1-v10/V6N4.pdf.

For an overview, there's a diagram:

(diagram link: https://airwingmedia.com/downloads/lockheed-c130-hercules/).


What aircraft or airline differences would make the Sukhoi Superjet unsuitable for US regional airline operations?

This is some speculation, but one potential reason is that U.S. carriers already have fleets of Embraer and Bombardier jets in this basic size (the Su-100 competes directly with the Embraer 190/195 and Bombardier's larger CRJs and upcoming C-series). The companies making these jets are located in pretty firmly U.S.-allied countries that are unlikely to see any economic restrictions that might hamper the ability of U.S. regional carriers to procure new airframes or parts.

The same cannot be said for Russia, which from 1946 until 1991 was pretty much embargoed by NATO signatories, and the relationship between Russia and the West since then has been testy. While the U.S. currently does not have a trade embargo with Russian civilian jet production operations (current sanctions attempt to specifically target military R&D and direct investment), that can change in a heartbeat if Russia continues to throw its weight around in neighboring countries.

Second, the seating capacity of this jet is a bit of an odd duck, as it blurs the line between the needs of regional vs. national U.S. carriers. The basic problem is that regionals, by their very nature, operate out of smaller cities with fewer potential passengers, at distances from major hubs that makes driving to that larger airport and flying from there more palatable for passengers. These considerations cause passenger count on regionals to drop off dramatically compared to longer "national" routes. The largest thing American Eagle currently flies is a Bombardier CRJ-900 (75 passengers in 2-class config), with the most commonly operated jet in AE's fleet being the Embraer ERJ145 (50 seats all-economy). By comparison the smallest plane operated under the full American badge is the A319 (124 seats in 2-class config).

There's an obvious gap between the two subsidiaries' aircraft capacities, but not much interest (by American at least) in filling it with a 100-seat jet like the SSJ100 (or E195 or C100). The primary reason is the collective bargaining agreements that pilots have with the airlines; they include, among other things, a requirement segregating the aircraft used by regional versus national subsidiaries. If you want to fly a plane with more than 80-100 seats (depending on exact terms of the agreement) on the route, you're paying a national airline flight crew the extra bucks to fly it; it's a violation of the CBA to put a 737 or A319 in the hands of a regional airline pilot because that takes the job away from the more senior pilots.

A secondary reason is that U.S. domestic airlines like American tend to favor more, smaller flights over fewer larger ones. This allows the airline to "rightsize" the route schedule (and its fleet) to passenger demand more closely and with fewer disruptions. If on a given day of the week, 200 passengers need to get between a regional airport and a larger hub, the airline could do that with four 50-place jets, or 3 75-place jets, or two 100-place jets. Theoretically, if demand were constant, it could save money the fewer flights it made, as the cost of the 50-seat Embraer's two-man flight crew would be roughly the same as the Sukhoi's, but with the Sukhoi you spread that cost over twice the passengers so your gross margin is higher.

However, an empty seat is a big fat goose-egg on the revenue for that seat for the flight, so if passenger demand varies (and it does, from day to day and seasonally), running larger jets either forces you to turn away some customers that you can't fit into the reduced schedule, or add flights that run mostly empty. Neither of these are palatable options for the airline; one pushes potential customers into the arms of their competitors, while the other has you running at least one flight that day costing tens of thousands of dollars for a handful of people with tickets whose regional component of the price might not even cover the pilot's salary for the duration of the flight (regionals are often "connecting" flights; DFW to PHX costs about \$320, ACT to DFW about \$300, but ACT to PHX via DFW only costs about \$360, so depending on how you part it out, the ACT-DFW leg of ACT-PHX might only really make you \$40 a seat, which might not break even if the plane's full, much less if it's half empty).

So, assuming any plane an airline would buy or lease is profitable when it's fully loaded with paying customers, American is more likely to successfully operate a route, and its entire network, using more smaller planes and scheduling a different number of interchangeable airframes and flight crews each day to maximize utilization, than it would be trying to also minimize the number of flights by using a variety of airframe sizes, which involves ensuring those airframes and the flight crews to run them are all in the right places at the right times (and deadheading - flying an empty plane from where it is right now to where it will be needed later - is bad no matter what the plane size, but typically more palatable with a smaller jet that has lower total operating costs).

Now, American isn't the only carrier with a regional subsidiary. US Airways Express and JetBlue, as well as several other New World regional carriers outside the U.S., regularly operate 100-seat Bombardier and Embraer airframes on regional connectors, and it would stand to reason that Sukhoi could get a piece of that action. It could also "stretch" the Superjet and try to compete in the national domestic market with the 125-seat A319 and 737-700 which are becoming more and more popular as U.S. domestic flights get "rightsized". However, the delicate nature of Russian-Western relations will probably continue to make Sukhoi a risky proposition for U.S. carriers that need a reliable source of airframes and parts on a 20-25 year timeline.


What can be considered under 61.113 (c) for passenger equipment?

Incidental costs specific to the passenger, such as O2 for the passenger's medical condition, may be paid by the passenger and need not be factored into the cost of the flight for flight sharing costs.

In your example, the Hobbs charge for the aircraft is the flight cost.  If the passenger wants a headset, or anything else that is not a flight expense, the cost need not be shared.

Landing fees, navigation fees and the like are grey areas, and I would split those.  But something like a tie-down or hangar fee is not a flight expense, and the passenger may pay for in full.

If you read cases where the FAA has prosecuted pilots for conducting operations "for hire" or similar, they tend to be egregious.

So in your example, $60 would be the right answer.  I would suggest that you could even split the cost of the charts you might buy for the trip.

As a final word, I would make certain that your passenger understands that you are just sharing expenses, not that they are "paying for a ride."


Does an AQP line check conducted by a part 121 carrier count as a flight review and instrument proficiency check for part 91 operations?

It depends if the AQP qualifies as a pilot proficiency check.  Most likely the the outcome will be a pilot proficiency check.

  §61.56   Flight review.

    ...

    (d) A person who has, within the period specified in paragraph (c) of this section, passed any of the following need not accomplish the flight review required by this section:

      (1) A pilot proficiency check or practical test conducted by an examiner, an approved pilot check airman, or a U.S. Armed Force, for a pilot certificate, rating, or operating privilege.


How much force is produced by control surfaces?

From the OP, it seems like you are treating the aircraft as a point mass. As a point mass, you don't get the rotational degrees of freedom, so control surface can't be accurately modeled. In the case of takeoff, rotation is achieved via elevator up force, resulting in aircraft pitching up, increasing its angle of attack, resulting in increased the overall lift and achieving the initial vertical acceleration. In summary, you can't model it from first principle without the rotational degrees of freedom.

There are a few things you can do.

You can continue to assume point mass. You can assume some simplified parametric model for takeoff rotation. That is, the trajectory is a parametric relationship of airspeed, time and elevator. It's not a physical model and it won't be accurate to the magnitude of elevator application, but it may suffice. Once in the air, you can do the same thing with banked turn for aileron applications, and airspeed changes with elevator. Essentially, you are working with a performance model (see performance equations of motions), with artificial relationships for control surfaces.

The above may suffice if all you want to do is GTA style flying (as an aside, its takeoff behavior is terrible). It'll look like a plane flying, but won't feel like a plane flying to anyone who's flown a plane.

You can move up to six degrees of freedom. In that case, you'd need more than just lift, drag and thrust; you'll need moment relationships as well. I recommend you to give Etkins, Dynamics of Flight a read. You can skip directly to Chapter 4. You'd be in very good hands once you've read Chapter 4 and 5.


In the old days, why didn't aircraft use simpler systems to land on a Carrier?

The benefit of a cable is that it's a mechanical means of arresting the aircraft. You either catch the cable and stop, or miss and go around. Aside from breakage and malfunction, there is no in-between. If braking is left entirely up to the pilot, it's up to them to engage all the right functions quickly enough, and in sufficient amounts. If they misjudge, they end up going into the water.
Cables are also effective at stopping aircraft quickly. This means less deck space is needed for landing, and with the introduction of the angled landing area, allows aircraft to be launched and recovered at the same time. Only a tail hook is needed to be added to the aircraft, which adds great braking effectiveness for relatively little weight. Other options have reasons they would be less effective than cables, with greater penalties in areas such as weight.
Reverse Pitch Propellers (reverse thrust)
This can be an effective way to help slow a propeller aircraft down. The downside is that it's up to the pilot to engage the reverse pitch and in a sufficient amount. Single engine aircraft can be hard to control especially if higher power settings are needed while in reverse.
Powerful Brakes in the rear wheel, or all wheels
Brakes are limited by the friction between the wheel and the ground. On carriers, this was generally wood, later replaced by metal. Especially when wet, this does not provide very much friction. Increasing downforce (see the air brake section) can help, but only to an extent. And as you noted, especially with tail draggers used on early carriers, aircraft would nose over if they braked too hard. The tail wheel doesn't have much weight on it, so would not be effective in braking.
Drag Chute
You'll notice that pretty much the only aircraft that use drag chutes are aircraft that land at high speeds and already need long runways. This is where you get the most benefit from a chute; long landing rollouts at high speed. As speed is reduced, they become less effective. You need to spend the time recovering, repairing/replacing, and re-packing the chute after each landing. They are also going to be less reliable than a tail hook. If it fails, you can't land on the carrier, you may just have to bail out.
Air Brake
Air brakes are similar to drag chutes in that they work best at high speed. While they are are not a consumable item, the drawback is that they have much less area, and therefore much less effectiveness than chutes. They work best when they can also provide downforce to improve braking friction, but still need high speeds and long distance to really provide benefit.
Carrier aviation in World War II was certainly dangerous. Many pilots died in accidents rather than in combat. But the military was still learning about how useful carriers would be in combat, and figuring out what the best configuration for carriers and their aircraft would be. Carrier aviation has come a long way since then, and cables are still the go-to system for recovering aircraft that don't at least have some kind of STOVL capability.


Why does aileron response diminish as speed becomes slower, from slow-flight up to the stall? (In a light trainer)

This is real easy, no explanation required:
Tell your student to stick their hand out the window of the car driving 25mph in the city and rotate it like an aileron.
Then have them do it on the freeway doing 60mph.
Feel the difference?  Did smaller movements produce larger effects at higher speeds?
Practical examples are typically more effective at driving a point home than a lot of words.


Which modern day prop (piston) engines allow for inverted flight?

Any “modern day” piston engine can allow for inverted flight if it has the right equipment on it.

The American Champion Citabria with the 7KCAB Inverted Fuel and Oil package along with the American Champion Decathlon are both "Modern Day" aircraft capable of sustained inverted flight.

The major differences between the7GCAA and 7KCAB were in the fuel system and the engine oil system. The engine was replaced with a Lycoming IO-320-E2A of 150 horsepower (110 kW), while a header tank of 1.5 gallons—located beneath the instrument panel—was added to the fuel system. In addition, the carburetor was replaced with a fuel injection system, and a Christen Industries inverted oil system was fitted to the engine. All of these changes were made in order to allow for extended inverted flight, a mode not possible in the earlier models.

disciplesofflight.com/american-champion-decathlon/
You can fly inverted continuously for about two minutes before the fuel in the header tank runs out and the engine falters. Rolling upright will recharge a depleted header tank in about a minute while the faltering becomes a smooth running engine again


How to know that ADS-B position messages are not spaced more then the 1/2 zone limit?

Usually you use a time limit between ADS-B position messages depending on the type of encoding used (surface or airborne)  and related assumed maximum speed to ensure that the aircraft cannot have travelled more than half a zone. If you don't receive a new position message within the time limit you will have to use global encoding (for which you need an odd/even pair of position messages within 10 seconds).

If I remember correctly, for airborne decoding an assumed maximum ground speed of 1000 knots is normally used. For surface decoding it is probably 200 knots. The latter gives problems when airborne aircraft send messages in surface format (e.g. due to a system fault).

In addition you can perform a number of tests that show that the newly decoded position is reasonably close to where it was to be expected.

For details see RTCA DO260B or EUROCAE ED102A (they are equivalent). They describe the encoding and decoding of (1090ES) ADS-B messages for airborne applications. In addition you can use EUROCAE ED129B. It is dedicated to ADS-B receiver systems for ATC (for gound based and space based receivers) and it includes a description of the decoding logic and related tests.


Why might DTK on GPS not match depicted course on approach plate?

Here is the final answer handed down directly from the Garmin technical support department. After a conversation with one of their aviation technicians, he told me that the error seems to be in their database. The same discrepancy (a track of 159 instead of 157) appeared whenever he reviewed the KRNT 16 RNAV Y approach from his end. He even rolled back the database to check previous versions and it has been this way for quite awhile. When asked about a possible magdev discrepancy, he said they they acquire all of their deviation data from the same governmental source that the chart makers do. He said that they are releasing a magdev update in the near future that MIGHT fix the problem, but said that it was most likely just entered wrong in their database. He opened a case file to make sure  it is addressed and said that he will notify when it has been taken care of.


What is this part which is mounted on the wing of Embraer ERJ-145?

They are called vortilons. They can induce a vortex to the upper surface of the wing at high angles of attack, which allows flying at higher angles of attack before stalling.

Additionally, four vortilons were installed on
the lower surface leading edge of the outboard wing panel. Their interaction with the wing sidewash at high angles of attack produce
strong vortices that are convected to the upper surface, where they
modify the pressure distribution and boundary layer development,
postponing flow separation and increasing maximum lift. Their
shape and position were defined using the 3D panel program. The
combined effect of the leading edge droop and vortilons allowed an
improved take-off and landing performance without resorting to
more complex variable geometry leading edge devices (such as
slats), for a small cruise performance penalty. Figure 22 shows a
schematic representation of the ERJ145 droop and vortilon.

(The evolution of the aerodynamic design tools and transport aircraft wings at Embraer)
They were first used on the Douglas DC9. The original patent shows the vortex on the upper side of the wing:


How are both squawk and altitude transmited when operating a Transponder in Mode C?

Squawk codes (Mode A replies) are transmitted in response to Mode 3/A interrogations. Altitude codes (Mode C replies) are transmitted in response to Mode C interrogations.
Both Mode A and C replies use the same 12 pulse encoding, but the radar that asked the question knows how to interpret the answer (assuming there is no FRUIT or garbling, but that is another topic).
If the transponder is in altitude reporting mode (i.e. it replies to Mode C interrogations), it will also reply to Mode 3/A interrogations.
Thus, if you squawk 7700 and you transponder is switched on (either Mode A only or Mode A/C), then code 7700 will be the response to the next Mode A interrogation from a radar. If your transponder responds to Mode C interrogations as well (i.e. altitude reporting is on), the radar will receive altitude information in response to Mode C interrogations.


What is the relationship between fuel mixture, throttle setting and engine temperature?

This image from Lycomings leaning instructions is likely what you are looking for:

The misnomer may be that leaning always increases the temperature of the engine. If you start at full rich or something above peak lean temp, leaning the engine will cause the CHT and EGT to rise until it hits its peak. If you continue to lean beyond this the temperature will start to drop again, and rapidly, but so will the power generated and at some point you run the risk of simply cutting the engine out so generally you want to lean to "peak EGT" since thats as low as you are practically going to want to go (unless you want worse fuel economy while flying slower).
If you look at the chart you will see below peak EGT your specific fuel consumption will also start to increase again.
Broadly speaking you can also see that increasing the mixture within its general operating range has a cooling effect on the engine.
If you are flying GA planes I would say the primary points in regards to engine temp is simply:

Keep an eye on temps and don't overheat the engine.
Lean slowly and carefully, keeping an eye on EGT or CHT for warm up which may not be immediate while leaning

If the gauge is creeping up, richen the mixture and consider reducing your angle of climb to increase airflow over the engine.


What factors made my flight land at runway 02 in El Prat?

Because 02 is the default runway for landing during nighttime (23 local time to 07 local time).

Night time configuration between 2300 and 0700 LT:
Preferential: North configuration intersecting runways
Arrivals: 02
Departures: 07R

(AIP Spain AD-2 LEBL - 8)
Airports usually have preferential runway configurations that will be used unless certain conditions (such as weather) require something else. These are usually created to avoid excessive noise to adjacent residential areas and to maximise traffic throughput.


Yes - it can work. Colin Furze (UK inventor & TV personality) built an essentially similar device. Skip to about 1:40 to see some of the problems he had.


How is spilled fuel cleaned up at airports?

Depending on the quantity, jet fuel can be cleaned up by use of a sump truck and dry absorbent material or if permitted by the airport and local environmental regulations, the fire department can spray water to wash it down the storm drain.


How are weight ranges mentioned for GA airplanes in TCDS?

Are there general aviation aircraft that have more than 2 "ranges"

Yes. I happen to fly one (the PA-28 series, TCDS 2A13).
The loading graphs look like this:

Note also that the aircraft is certificated in both the Normal and Utility category, and the weight/CG ranges are different (Utility being a subset of what's permissible for Normal category operations) - so there are two different operating envelopes that must be considered.


Why does a turbofan shut off when rapidly retarding the thrust levers?

The rotational inertia of the fan will continue to push air through the engine after the fuel supply has been reduced. Reduce the fuel supply too quickly and the result is like holding a match in a gale: the wind blows the flame out.

To prevent this, modern engines use digital controls (FADEC) to ensure that the engine is kept within its operating parameters regardless of what the pilot might do with the throttle.


Is every emergency landing of a commercial flight documented?

Generally there should be some kind of record of this incident but even more broadly speaking not all aviation accidents are necessarily documented or reported on a global scale.

It depends on what country you are in and who the reporting agency is. Here in the USA the NTSB is responsible for investigations of aircraft incidents. Investigations and reports are generally the responsibility of the country in which they happen but not all countries have investigation agencies nor the means to carry out complex investigations. Historically the manufacturers as well as other nations have offered assistance when need be as the outcome is as important to them as it is to the investigating agencies.

As for Greece their reporting agency can be found here and the list of 2006 reports here although they seem to publish the list by year that the report came out (not the year of the accident) so the 2007 list may also be of interest. Most of the reports are published in greek which I cant read and there does not seem to be one relating to Royal Jordanian.

Not that it is a complete list by any means but wiki does not list any similar Greek aviation incidents on their compiled list.

For the sake of completeness, what appears to be a grass field to some may actually be a grass runway (more common than you would think) and its possible what your friend described was a landing at a grass runway (field, or strip) done for a precautionary reason. A diversion like this may not cause an investigation to ensue.


How is the fuel quality monitored/assured for jetliners?

As you can see, the supply chain is big (with filters and water separators at various points). The short answer is that standards and quality checks are followed.

As for the jetliners, as far as I know they can't detect the fuel quality, but some can alert if issues arise in the fuel filters. The certification standards focus on engine restart capability and that it...

  ... should be demonstrated for the momentary shutdown from a high power or thrust setting, associated with the takeoff and climb flight regimes, and the extended shutdown at medium to high altitude where the engines may be "windmilling" and/or "cold soaked."

Fuel contamination is of the reasons mentioned in the engine restart section.

ICAO's Manual on Civil Aviation Jet Fuel Supply (on SKYbrary; PDF) is comprehensive as to the practices involved (the image above is from the manual).

  1.2.1 Any business entity involved in the aviation fuel supply chain has an obligation to implement and comply with industry and/or company proprietary PSPs, as described in this manual, that cover the activities in which they are involved.

Supply and distribution, aircraft operators, and airport operators, each follow their respective policies, standards and procedures (PSP).

  3.10.1 Any organization that manufactures, supplies or handles aviation fuel should have a documented training programme for its personnel. The programme should cover product quality, safe operation of equipment, emergency procedures and occupational health, as well as management systems for operational safety, environment and security. In particular, the programme should include in its scope a systematic way to identify hazards and effectively control risks to fuel quality, personnel, and facility and equipment or aircraft safety.

At each step the manual lists the various industry standards and manuals to follow.


Why not use flaps in take off from High Density Altitude airport?

With more flaps, you will lift off at lower speed, but will have worse climb performance due to the increased drag.

On short field you are limited by the field length, so you need to lift off early and therefore need to use more flaps.

But in the mountains you are limited by the climb performance. Therefore you need to use less flaps.

Of course, this is just general rule. You should look up performance for given density altitude and compare it with available runway length and required climb gradient.

Update: Extending flaps never improves rate of climb. Up to some points it does improve angle of climb though, because it reduces Vx and the engine can produce more thrust at lower speed. The setting for best angle of climb is higher than for normal take-off and is used on obstructed field.

However as excess power reduces (with density altitude), Vx increases towards Vy (at absolute ceiling, Vx = Vy and rate of climb is 0) and the flap setting for best angle of climb decreases. So even for best angle of climb you shouldn't use as much flaps at high density altitude as at low.

And most mountain airports are not obstructed. In most cases the valley ahead is large enough, but you want to get above the tricky winds fast and you want high rate of climb in case you encounter a downdraft. And that means no or little flaps.


What is the meaning of a flashing white signalling light in Aldis Lamp?

The signal you are talking about relates to vehicles (flashing whites can also apply to aircraft, but then it has a different meaning).

Local instructions refers to the local written rules/procedures applicable at the specific airport. In order to be allowed to drive on the maneouvering area, the vehicle driver will have undergone training and have read the local procedures. Maybe the local instructions requires the driver to leave the maneouvering area via a specific route or in a certain direction. In such cases, that would be written in the local instructions. They are called local because they are only valid at that specific airport.


Can a part 103 ultralight weigh 400kg fully loaded?

Part 103 limitations pertain to dry weight in takeoff configuration, maximum stall speed, maximum level flight speed, and maximum fuel capacity.  They do not directly address maximum gross takeoff weight.

However, weight affects stall speed, and I'm not certain how Part 103 defines its stall speed limit -- whether they specify at some minimum operating weight, or at "design weight" or some other value.  The complete regulation is available online, however, so you can read it yourself and determine if you'll be able to design for your maximum 400 kg GTOW.