What is the pattern of the flashing light in Airbus A340-300? I'm looking for the lights and flashing patterns of the Airbus A340-313 (or any Airbus A340).

My question is related to this one: Do lights on aircraft flash in a specific pattern?

but is very specific for this model.

In any case I'll be grateful is there is some page or link with the patterns of several models (so I don't have to disturb you in the future :) )

Thanks in advance.

For the lights on the A340-200/-300 see Documentation page 129.

For the lights on the A340-500/-600 see Documentation page 133.

Use the following link to see the lighting regulations for commercial aircraft -  http://www.whelen.com/pb/Aviation/System%20Requirements/Anit-Collision%20Systems.pdf

Use of lights

AIM 4−3−23. Use of Aircraft Lights was updated in the latest edition.

Guidance about using aircraft lights during ground operations also appears in AC91-73B, “Part 91 and Part 135 Single-Pilot Procedures during Taxi Operations.”

h. Use of Exterior Aircraft Lights to Make Aircraft More Conspicuous.

(1) General. Exterior aircraft lights may be used to make an aircraft operating on the airport surface more conspicuous. Pilots may use various combinations of exterior lights to convey their location and intent to other pilots. Certain exterior lights may also be used in various combinations to signal whether the aircraft is on a taxiway or on a runway, in position on the runway but holding for takeoff clearance, crossing an active runway, or moving down the runway for takeoff.

NOTE: Because adherence to the guidelines in this AC are voluntary and aircraft equipment varies, pilots are cautioned not to rely solely on the status of an aircraft’s lights to determine the intentions of the pilot(s) of the other aircraft. Additionally, pilots must remember to comply with operating limitations on the aircraft’s lighting systems.

(2) Because adherence to the guidelines in this AC are voluntary and aircraft equipment varies, pilots are cautioned not to rely solely on the status of an aircraft’s lights to determine the intentions of the pilot(s) of the other aircraft. Additionally, pilots must remember to comply with operating limitations on the aircraft’s lighting systems.

(2) Exterior Lights. To the extent possible and consistent with aircraft equipage, operating limitations, and pilot procedures, pilots should illuminate exterior lights as follows:

(a) Engines Running. Turn on the rotating beacon whenever an engine is running.

(b) Taxiing. Prior to commencing taxi, turn on navigation, position, anti-collision, and logo lights, if available. To signal intent to other pilots, consider turning on the taxi light when the aircraft is moving or intending to move on the ground, and turning it off when stopped, yielding, or as a consideration to other pilots or ground personnel. Strobe lights should not be illuminated during taxi if they will adversely affect the vision of other pilots or ground personnel.

(c) Crossing a Runway. All exterior lights should be illuminated when crossing a runway.
CAUTION: Pilots should consider any adverse effects to safety that illuminating the forward facing lights will have on the vision of other pilots or ground personnel during runway crossings.

(d) Entering the Departure Runway for Takeoff or LUAW. When entering a runway after being cleared for takeoff, or when taxiing into position and hold, pilots should make their aircraft more conspicuous to aircraft on final behind them and to ATC by turning on lights (except landing lights) that highlight the aircraft’s silhouette. Strobe lights should not be illuminated if they will adversely affect the vision of other pilots.

(e) At Night, and When Cleared to LUAW. Consider lining up slightly (approximately 3 feet) to the left or right of the centerline (CL) to enable a landing aircraft to visually differentiate your aircraft from the runway lights.

(f) Takeoff. Landing lights should be turned on when takeoff clearance is received, or when commencing takeoff roll at an airport without an operating control tower.


Do modern aircraft require rudder input in order to perform a coordinated turn? With today's state-of-the-art electronic systems in modern aircraft, do aircraft equipped with autopilot systems, still require pilot rudder input to keep a turn coordinated?

For the context, I'm assuming the pilot is hand-flying the aircraft so the autopilot must be at least partially disengaged to let the pilot manually initiate and perform the turn via the yoke/stick, but still make the rudder use unnecessary or optional.

For example, would an F-16 pilot still need to apply the rudder during a turn? If the military case is not generic enough, how about an airliner pilot? Or a GA aircraft like the Cirrus SR22?

Most transport aircraft use yaw damper systems to take care of minor rudder inputs.  Most autopilot systems are actually only 2-axis - pitch and roll since the rudder's job is only to keep the tail lined up behind the nose.  The yaw damper is a separate "autopilot" system and has limited authority, sufficient to deal with minor yaw disturbances, dampen dutch roll, and counter adverse yaw from the ailerons and is active all the time whether the autopilot is on or not.

With a Y/D system the only time a pilot really needs to make a rudder input in flight is if an engine quits, because the yaw damper's authority is not sufficient to counter asymmetric thrust.  Generally in a jet, once through the departure profile, feet are on the floor even when hand flying.  They are only on the pedals to steer the nosewheel during the takeoff and be ready in case an engine quits.

On a swept wing aircraft the yaw damper is essential; if the yaw damper is off and yaw disturbances occur, dutch roll motions can start and if the pilot tries to respond with rudder inputs he almost always can't stay in phase and things get exciting.  Because of this criticality the Y/D is usually dual channel.  One of the tests done on production aircraft is to induce a large yaw movement with both YD channels off to get a dutch roll going, then engage each YD channel and make sure it stops the dutch roll.


How do I tell ATC that I don't have a transponder? If my plane doesn't have a transponder and ATC tells me to squawk some transponder code, how should I respond? Is it just as simple as "I don't have a transponder"?

This is for the United States and for a plane with no electrical system, and obviously at a towered field where I would be communicating with ATC using a portable radio. No flight plans will be involved and I will generally be flying out of a class B field but within a class B umbrella. Flights will be VFR/daytime only.

EDIT: Looks like I opened up quite a can o' worms, here. I didn't know it would be this complicated. Just found this, too, which adds some more info. Thanks for the lively debate and the good suggestions.

https://www.aopa.org/training-and-safety/pic-archive/equipment/transponder-requirements

Looks like it's getting more and more difficult to escape government control. I think I may have to get a transponder. Hmmm.

From the AOPA:

  Flying into a Mode C Veil Without a Transponder

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

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

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


Why doesn't ice form on the fuselage? Ice forms on the wings and instrument probes and vanes, but why not on the fuselage? If the temperature of the air is the same, why does the ice form on the wing but not on the fuselage?

It does, but there is much less of it on the fuselage than on the wing.

There are two ways how ice is accumulated on the aircraft's structure:

When flying through air containing supercooled water droplets, the water will freeze on impact. It does not make much of a difference whether the water impacts the fuselage nose or the leading edge of the wings and tail surfaces: It will form a sheet of clear ice.
When flying through moist air at a temperature close to freezing, the pressure loss of the air flowing around any obstacle will cool it down, so the moisture condenses and, if temperature allows, will form ice accumulations. Those in turn exacerbate the suction peaks, leading to more ice being collected.

The wing's leading edge shows the most pronounced suction peaks, so they will collect most ice. However, if the icing conditions are right, the fuselage nose will also pick up it's share of ice. Along the length of the fuselage, pressure is similar to ambient, so it will collect ice only when sitting on the ground in freezing rain.

Iced engine nacelle in the NASA Lewis (now Glenn) Research Center icing research tunnel (picture source). Here, water is sprayed into the tunnel and forms supercooled droplets.

In both cases icing has nothing to do with the boundary layer - with supercooled water it is simple ballistics, while the second case of ice accumulation is dominated by the pressure of the flow around the aircraft.


What causes a plane's wing tips to leave a small white vapor trail? What is the source for what looks to be small trails of smoke or condensation sometimes coming from the very tips of a jet aircrafts wing tips?

The cause is reduced pressure in the wingtip vortex trailing behind the wing. Reduced pressure causes reduced temperature and if ambient humidity is high enough the result is the  condensation you observe.


How do pattern and overflight altitudes work for airports underneath Class C airspace? Lowell City Airport (24C) has an elevation of 700 feet MSL. So normally, the pattern altitude is going to be 1,700 feet, and the altitude for overflying the pattern is going to be 2,200 feet.

However, 24C Lowell is located underneath Class C airspace which starts at 2,000 MSL, so you can't fly at 2,200 without talking to Grand Rapids.

What should I do if I'd like to fly over the field? I can think of a few options:

Maybe 24C Lowell has a non-standard pattern altitude, like 1,400, which would allow me to overfly at 1,900. (How could I find this out using official sources?)
Split the difference between pattern altitude and the Class C. If the pattern altitude is 1,700 and the Class C starts at 2,000, maybe I can overfly at 1,900.
Establish communications with Grand Rapids Approach, then go ahead and overfly at 2,200 while monitoring both Approach and CTAF at the same time.
Just avoid overflying the pattern, and fly around it instead.

When in doubt, I'm going with option 4. But what should I know about the other options?

I do have some particular questions about option 3. If I do choose to contact Grand Rapids Approach and climb to 2,200 to overfly, then I'll have to monitor both Approach and CTAF at the same time, right? Can most small airplanes even do that?

Just talk to the controllers. We live under a Class B with several underlying Class C or D fields. They'll talk to you. They'd rather know what you're planning to do than not, keeps everyone safer.


Why aren't runway numbers painted in a higher aspect ratio? I'm watching a lot of aviation youtube channels and it seems to me that when attempting a landing on a "normal" glide path, it must be quite hard to read the runway numbers until you're on short final, which might affect the number of "wrong runway landings", especially on uncontrolled airfields.

Are they actually easier to read in reality than in the videos I'm watching?
If not, why aren't they painted with a higher aspect ratio (e.g. the numbers being twice as high, thus making them appear "less vertically compressed" when approaching on a "normal" glide path)?

Runway numbers need to be readable from multiple angles, they aren't just for those on approach. Joining at uncontrolled airfields is usually done by flying over the airfield or approaching from any point on the compass, aspect ratios opposite to your viewing angle are hard to read and therefore counter productive for those in the pattern.


How does fuel economy quantitatively depend on altitude for a jet? We already have a few questions and answers about the qualitative effects of altitude on fuel economy:

How do I determine the best altitude to fly for fuel economy?
Why does fuel consumption decrease with increasing aircraft altitude?
What is the relation between an airplane's altitude and the drag it is experiencing?
Why do jet engines get better fuel efficiency at high altitudes? (contains formula for thermal efficiency)

I am interested in understanding how the changes in pressure and temperature at different altitudes affect the fuel economy of a turbofan powered aircraft quantitatively. In the end, I would like to make a plot of relative fuel economy vs. altitude that takes all of these effects into account, but I don't know how to quantitatively combine these effects.

Some notes:

By fuel economy I mean fuel required per distance traveled, not time.
I am not interested in absolute numbers for the fuel per distance, which would require specifying a particular aircraft. I am only interested in how the fuel per distance figure would relatively change with altitude, e.g. normalized to 1 at sea level.
I assume ISA (International Standard Atmosphere) profiles for pressure and altitude.
I assume the no wind case. Different winds at different altitudes will of course have an effect on the result, but it is easy to take this into account after the no wind case is understood.
Let's assume a typical climb profile for a short- to medium-haul jet airliner: 250/280/0.78

You can see that the TAS increases until reaching Mach 0.78, then decreases due to the lower temperatures causing a lower speed of sound and then remains constant above the tropopause. I am particularly interested in how the fuel economy will behave around these altitudes.

I am adding this community wiki answer to show my current state of research and to provide the plot vs. altitude, which I will update when I learn more. Comments are welcome.
Thermal Efficiency
From this answer by Peter Kämpf, we know that the thermal efficiency for jet engines is given by
$$ \eta = \frac{T_\text{max} - T_\text{amb}}{T_\text{max}} $$
where $ T_\text{amb} $ is just the ambient temperature (from ISA) and $ T_\text{max} $ is the temperature resulting from the combustion. If I understand the answer correctly, this should be about 1100 K above ambient temperature, so I am currently using this term to describe the impact of thermal efficiency on fuel economy:
$$ \epsilon_\text{T} \propto \frac{1}{\eta} = \frac{T_\text{max}}{T_\text{max} - T_\text{amb}} = \frac{T_\text{amb} + 1100 \, \mathrm{K}}{1100 \, \mathrm{K}} $$
I am not sure if the increase in temperature of 1100 K is constant with altitude, so please correct me if this is wrong.
Drag
From another answer by Peter Kämpf, we know that induced drag is proportional to dynamic pressure
$$ q = \frac{v^2}{2} \cdot \rho $$
with $ v $ being the TAS and $ \rho $ the density (known from ISA). Since work required to overcome the drag per distance is proportional to the force, the fuel economy should just scale with
$$ \epsilon_\text{drag} \propto \text{TAS}^2 \cdot \rho $$
Propulsive Efficiency
From this answer we know that the propulsive efficiency for a jet engine is given by
$$ \eta_p = \frac{2}{1 + v_e / v_0} $$
where $v_e$ is the exhaust velocity and $v_0$ is the TAS. As far as I could find, there is no straight-forward way to relate $v_e$ to altitude and temperature. For the moment, I added the propulsive efficiency for a high-bypass jet engine from the following plot from Wikipedia:

(image source: Wikipedia)
Summary
For the combined (relative) fuel economy term, I just multiply all previous terms:
$$ \epsilon = \epsilon_T \cdot \epsilon_\text{Drag} \cdot \epsilon_\text{Prop} $$
The following plot now shows the relative fuel required per distance. Each curve has been normalized to 1 at sea level.

The propulsive efficiency dominates as long as the TAS is increased. Afterwards, the lower drag dominates. The overall fuel use is almost half as low at high cruise altitudes compared to sea level.


What is the process to disconnect ground electric power before pushback? While commercial airliner are parked at the gate, they have electrical power connected to the aircraft (if available at the airport). This needs to be disconnected before pushback - what is the process to do so?

How does the ground crew know it is safe / ok to disconnect ground power? (ask pilot if Auxiliary Power Unit (APU) is running?)
When will it be disconnected? As late as possible before push-back?

Thanks!

When is the GPU disconnected?

Airports rules are applicable, for example airports may prevent the use of APU when the aircraft is at its stand (to reduce noise and pollutants release). The airline operating procedures also provide directives regarding when to start APU and engines.

The general principle is that GPU energy is cheaper than APU energy, hence unless an engine is running, GPU is used until pushback starts.

Disconnection

When the crew is ready for the pushback they make sure they have the APU running and the GPU isolated from the electrical bus.

B737 overhead electrical panel, source

The ground operator is in contact with the crew through the flight interphone system. The crew asks for the pushback procedure. The ground operator now has to disconnect conditioned air and ground electrical supply.

On the ground power receptacle panel there are usually lights to indicate whether the GPU is connected and in use.

B737 external electrical panel, source

The operator checks the white light is on, which indicates the GPU is not in use and using a switch on the plug electrically disconnects the ground supply. The "CONNCT" light goes off and the cable is physically disconnected. At this time the GPU may be shut down, if applicable.

Chocks are removed, brakes are released and pushback can start.

More on ground handling procedures:

Cello Aviation B737 procedures

Currents required for 90 kVA under 115 V are about 1 kA. If the connection is broken when such current flows, the components just disconnected can melt down, and liquid metal can be projected around (it's similar to arc welding).

GPU are fitted with some protections to prevent hot disconnection. Let's look at this aspect.

Cable layout

A GPU delivers three-phase 115 V / 400 Hz, the GPU cable/plug contains therefore 4 main conductors and pins: one neutral used as common ground (N or G) and three phases (A, B, C). When the system is balanced, there is no current in the neutral, electrons move in phases only due to the voltage 120° phase angle difference.

N, A, B, C wires are connected to corresponding pins of the plug (E/F pins are explained below):

Plug (source)

At 400 Hz the reactance of the GPU cable is 8 times the reactance at 50 Hz, and is able to alter the phase angles at the aircraft interface, leading to significant power losses and under-voltage. Inductive reactance is due to the existence of a strong magnetic field near the conductors. This field can be cancelled by distributing the phase conductors around the neutral.

As the phase conductors have a large diameter, doing so leaves some empty space between the conductors. This means conductors may move within the cable when the cable is used. One solution to minimize this space is to split each phase conductor into two separate smaller conductors connected to the same power connector pin:

Source

Other solutions exist like twisted individual cables.

In addition an adequate mechanism can be used to tweak the reactance and/or the voltage when the cable is moved and its curvature is altered and/or when the electrical demand varies. This can be done by injecting some capacitive reactance into the circuit and/or adjusting the transformation ratio.

E/F control pins

Two smaller pins (E and F) of the cable plug are used for status exchange between the aircraft electrical system and the GPU. F carries 28 VDC from the aircraft. E and F are usually shunted in the GPU plug.

Standard wiring for civil aviation (source)

This way, when the plug is disconnected, the aircraft electrical system can inhibit its ground power input and the GPU can shutdown its power generators.

E/F are connected to corresponding smaller control wires visible between the phase conductors (when E and F are shunted, a single wire is needed).

Additional features

Control wires can be used to connect optional systems to the GPU:

Red/green (ON/OFF) push-buttons for remote control of the GPU.
E/F pins fitted with a small switch to know when the cable connector is 90% inserted within the aircraft panel socket and the connection can be seen as established.
When the cable comes from cable from the loading bridge, additional push-buttons for reel control: UP/DOWN, IN/OUT.
Sensors to detect reactance variation, hot cable/plug or broken neutral.

Conversely, LEDs on the plug can be switched on or off by the GPU using the control wires.

More information:

AXA 2300 GPU Manual


Does electrical usage contribute to fuel consumption? I know that while in-flight the electricity is produced by the engines.

What happens if every possible system requiring electricity is in the on state? This should require extra electricity.

Does this usage of electricity increase the fuel consumption by any means?

*Edit to include the additional question from the comments section:

Given that the engines require fuel to produce electricity how big is the impact on fuel consumption, speaking of "mainstream" airliners like the A320?

Short answer

In flight, unless you use external energy sources like the Sun, each change in the use of electricity leads to a proportional change in the quantity of fuel burnt in the engines (or in the APU).

On an aircraft, generators only convert fuel potential chemical energy into something else, usually electricity, hydraulic energy or pneumatic energy.

There is no other source of energy:

The batteries themselves need to be charged, charging burns fuel.
The RAT (ram air turbine) uses energy from the relative wind created by the engines thrust. If the RAT is used because the engines and the APU are down, the relative wind is due to the loss of altitude created by the gravity. This kinetic energy is the restitution of the potential energy accumulated during the climb with the engines, so with fuel.

Details

Maximum power of the electrical equipment

The electrical power needs of the whole aircraft can be completely met by a single engine generator, or by the APU. On the A320 family, the APU is an APS3200 delivering about 90 kVA.

APU fuel consumption

From this PPRuNE discussion, an A320 APU may consume 130 kg per hour on the ground, and 51 kg per hour at FL300. However the APU provides at the same time electricity and bleed air energy.

APU fuel consumption for electrical energy generation

However the fuel quantity used for the sole electricity generation may be approximated:

Maximum power required by the aircraft equipment → 90 kVA AC.
Assuming a mean cos φ = 0.8 → Apparent power = 110 kW DC.
Assuming 25% efficiency for the system (gas turbine + generator) → Fuel power required 440 kW.
Fuel energy required → 440 kWh per hour.
Converting to joules (1 MJ = 0.28 kWh) → 440 kWh ≈ 1,570 MJ.
Kerosene specific energy = 43 MJ/kg → Fuel quantity burnt in an hour = 1,570 / 43 = 36 kg (45 L)

So approximately 36 kg of fuel are required per hour to provide for electric energy on an A320.

Note that in flight all engines generators will be active and will share the total demand (feeding different buses for safety), and the APU will likely be inactive. The fuel consumption should be more or less the same, regardless of the number and nature of the active generators. An inactive or unloaded engine generator can be seen as not impacting the fuel consumption for practical purposes.

Engines burning the maximum rate of fuel

Engines have a maximal power. When the engines are already at full thrust, increasing the electric load will divert an additional amount of energy to the generator. This quantity being removed from the energy usable for aircraft propulsion, the aircraft will slow down.

(Updated, taking into account the multiple helpful comments -- Thanks!)

Bonus

Breathing increases fuel use too:

Each time a passenger breathes, they reject heat and CO2 which must be evacuated out of the aircraft.
Some quantity of air must be replaced by new air by the conditioning system.
This system uses pneumatic or electric energy, and again fuel must be burnt to create this energy.


What determines crosswind limits? What is typically the limiting factor for how large a crosswind component a given plane can be safely landed in?

My impression is that larger planes are less sensitive to crosswind than smaller ones -- for example, many commercial airports seem to be doing quite well with a single or multiple parallel runways for transport-category aircraft, whereas airports catering to light aircraft will be proportionally more likely to have (and routinely use) a system of intersecting runways.

I can imagine one reason for this, namely that a plane with a higher landing speed will need less of a crab angle for a given crosswind component. But is this actually the determining factor?

If yes, then is is safe/legal/practical to land a light aircraft in more crosswind than it can usually handle, by landing faster, assuming there's a nice long runway available to decelerate on? (In other words, can an airport make up for having no crosswind runway by having a longer primary runway instead?).

Your question is not easily answered, at least in my opinion, but I'll have a go at it.

Your impression that larger airplanes are less sensitive to xwinds than smaller airplanes is correct, very much so in my experience. I lack the expertise to give you the aerodynamic basis, the equations if you will, but I'm fairly certain that saying an aircraft's sensitivity to a xwind is inversely proportional to it's mass, landing speed, and wing loading is a correct statement. As I remember, the max demonstrated xwind for a Cessna 172 is 15 kts, for a 747 either 25 or 30 kts, and I would much rather be landing a 747 in a 30 kt xwind than a 172 in a 15 kt xwind. In 747 sims we would occasionally crank the xwind up to 40 kts for an interesting but still safe landing.

Using extra speed in a small aircraft to help is not, in my opinion, a good idea. You'd certainly want to add a bit to your approach speed to handle gusting conditions (which typically accompany crosswinds), but what you need to do is transition from flying speed to non-flying speed as quickly as possible rather than extending the time of that transition. You need to get the weight off the wings and on to the wheels as quickly as possible.

There is one exception to what I just said. Back in the 1950s when I first learned to fly, they used to teach what they called 'wheel landings' for handling crosswinds in taildraggers. The problem with a taildragger is that the c.g. is behind the main gear. If you touch down in any kind of a crab, it wants to switch ends. In other words, a ground-loop. The idea of a 'wheel landing' was to get the main wheels on the runway with extra speed (after having slipped to the touchdown) so that the rudder (with the tail still off the ground) had plenty of authority to counteract weathervaning, and of course with the upwind aileron fully up. Then you were supposed to keep the airplane straight while the your speed dissipated to where the tail could no longer fly. I have no idea if they still teach that technique.

So now you're the PIC and having to decide whether to land in a xwind. Following are some of the things I can think of that might enter into your decision making:

What's your personal confidence level? If you're nervous about the situation you're probably not going to do as good a job as if you were relaxed.
What's your experience level in the airplane? Aircraft, even of the same weight class, vary in their handling qualities in a xwind, and the more you've flown them in xwinds, the better you're going to be in that model of aircraft in a xwind.
High wing or low wing? The closer to the ground you get the more the wind decreases, and that few feet of difference can make a difference. Also, I suspect, but do not know, that having most of the wing below the c.g. rather than above the c.g. helps.
What is the runway surface, and what is its condition? In other words, how slippery is it going to be. A dry paved runway is, of course, the best. However, a dry paved runway with a lot of reverted rubber in 120 F (49 C) temperatures can be interesting. Ice or wet grass is perhaps the worst. I put a Cessna 150 off the runway in wet grass back in the 1970s.
How bad do you need to land there? Some might say that doubts about being able to safely land should always override the need to land, but that's not the real world.
For a light aircraft, you may be able to turn that strong xwind into a strong headwind by using a taxiway. I've done that at a uncontrolled field.

A word of caution: Just because the xwind is within the max demonstrated xwind component does not necessarily mean you can safely land, it just means an experienced test pilot did it on a reasonable runway surface. The max demonstrated xwind is a guideline that is sometimes safe to exceed, sometimes not, and sometimes not safe to even get close to.


What work besides flying planes does an airline pilot regularly do? What are the typical non-aircraft duties for an airline pilot?

By non-aircraft, I'm asking about time spent in the office, in meetings, training (whether in a simulator, class or other non-aircraft environment), deadheading or being at the airport but not actually in the aircraft.

I understand there is paperwork and pre-flight planning done on the ground between flights while in the cockpit, so I'm not asking about this. I'm really trying to get an idea about what other work related activities you do which does not involve you being in the cockpit (except perhaps purely as a work-related passenger).

Another way of asking this question would be, "what work besides flying planes does an airline pilot normally do, or might reasonably be expected to do, as part of his or her job?"

There isn't much non-flying duty for airline pilots.
The most important is recurrent training. Pilots are required to attend a refresher course at least annually. This school covers regulations, aircraft systems, and performance. The performance part involves computing weight and balance, airfield/weather restrictions, fuel required, etc (basically the same thing as a Cessna 172, but with much bigger numbers). Additionally, full flight simulators are used to teach and/or evaluate normal and non-normal (we don't get emergencies anymore) procedure. This training is usually concurrent with the groundschool.
Pilots are required to maintain their approach charts and aircraft manuals; changes come frequently.
A junior First Officer will spend an eternity (at least it seems like it) doing standby duty. This involves being available to take the place of any pilot who calls in sick or is otherwise unavailable.
All pilots must pass a flight physical. The implication is that they must maintain themselves in at least minimal health.

I hope this at least partially answers your question.


Do new VHF radios need to be flight tested? I'm in the process of upgrading all our VHF radios and the local regulator has asked us to follow the guidance/recommendations from ICAO, as we have more or less cancelled many of our local rules. The radios will be used for voice only (including Volmet and ATIS).

What do the ICAO recommendations/procedures say about installing new air-to-ground VHF radios? Do they need to be tested by a test flight? Is there a difference if it is a new installation with new radios and new antenna, versus new radio types but with the same antenna, same frequency and same power output?

Avionics shops almost never test VHF radios in flight. They are almost always tested on the ground with test equipment. The only time I can think of an in-flight test being required is if the technician is trying to troubleshoot an intermittent problem that only happens in flight (such as a faulty connector in the vibration-rich environment of a military transport helicopter).


Is it possible to convert a passenger A380 to carry cargo? I heard an expert say that one of the A380's weaknesses is that it only comes in a passenger version, not a cargo one like the B747 does. The cargo version of the B747 makes its market wider. One more weakness of very large jumbo jets (A380 and B747) is that, nowadays, most flights fly directly to the destination (point-to-point), not hub-to-hub as in the 1970s. The point-to-point model causes airlines to make more frequent flights with smaller aircraft. In my country, even small airports are now international airports. Two neighbouring cities in neighbouring countries have small propeller aircraft flying directly between them, without having to go through the main airport in one country's capital city. This makes it very clear that very large jumbo jets are no longer required for passenger service.

On the other hand, the demand for air cargo has never been greater. Trade over the globe has to be quicker. This means that large jumbo jets are needed in cargo service, and - to allow easy centralization of cargo-handling equipment and personnel - it's generally preferable for these freighters to operate to and from the largest, most central airports in a country.

The question is, is it possible to convert an A380 for cargo service when there is no longer a market for the passenger version?

Airbus originally planned on a freighter version and UPS and FedEx both ordered some of them. Production delays with the passenger version resulted in the freighter version being delayed and both of them canceling their orders.

The main issue why there is no freighter version is that the internal volume of the aircraft is too large to make it economical for cargo operations. I.e. the density of the cargo generally is too high to take advantage of the full internal volume before hitting the aircraft's maximum take-off weight. As a result, you end up hauling a whole lot of "extra airplane" around. The only time that extra volume is useful is for really low-density cargo loads.

That extra internal volume is useful if you have to move a large number of passengers into slot-constrained hub airport like London Heathrow or JFK but packages don't care much about personal space...

In words other than mine:

  An A380-F would be too fat to fly at a profit: The plane would hit the maximum payload (a constraint of weight) before its maximum cubic space (a constraint of volume). Its design can’t support the maximum payload required to generate a profit.

Here are some good other more in-depth analyses.

Something that was surprising to me initially was the amount of modifications that are necessary to convert a passenger aircraft to a cargo aircraft. This paper from a Bedeck Aviation Group (Boeing affiliated passenger to cargo conversion house) provides a good breakdown of the steps required for a 767 conversion. This video from Boeing provides a good visual summary as well (music and hair styles are an added bonus).


Do I need a stamp for my USPA license? A few weeks ago I finally finished all of my USPA A license requirements. My instructor signed off the final things and even the card but forgot to put the stamp itself on the form.

I was about to send the form off to get my A license card but am hesitant without the stamp. Do I need the stamp to have it processed? More importantly, will I be able to use my paper form as the temporary A license without the stamp?

I normally wouldnt have an issue just going back to see him, but I am overseas for several months and really wanted to jump when I take leave.

I'm hoping to find an instructor or someone with personal experience with this... Thanks!

I'm a USPA AFF, tandem, and static line instructor.  Your signed and completed A-License Proficiency Card is valid and USPA will process it without the stamp.  You only need the stamp if you want to go to another dropzone and use your card as a temporary license.

The proficiency card is only valid for 60 days after the date it was completed, so don't waste time sending it in.  The last I heard, USPA is taking 3-4 weeks to process license applications.

Edit to add:  Don't send in the actual card.  You can mail a photocopy, fax it in, or scan it and email it to membership@uspa.org.  Faxing or emailing will get you your official license a few days faster.


Would one expect Canadair CL-215 or CL-415 planes to be equipped with a working ADS-B transpoder? In a forrest fire in Greece, on which according to news sources eight such planes are operating as firefighters, no planes can be seen on Flightradar24.  Only a fire service's helicopter can be seen flying around.
Note that the planes in question are operated by the Hellenic Air Force.

Military operators can request that their aircraft are not shown on flightradar24.

Operators of private or sensitive aircraft may request their tracking details be restricted or not displayed. Generally, aircraft requesting that they not be displayed on Flightradar24 are military aircraft.

From: https://www.flightradar24.com/blog/whats-this-plane-doing-answering-recent-frequently-asked-questions/
Whether or not an airplane is equipped with ADS-B is entirely up to the operator. Both the CL-215 and CL-415 were designed before ADS-B existed. However, if the mission demands it, ADS-B capabilities may be retrofitted to existing aircraft. Whether this is the case for these particular Canadairs, I do not know (I expect not), but regardless, it's impossible to make any definite conclusions based on the absence on FR24 and related tracking websites.


How do pilots avoid radiation? It is said that they are exposed to 50% more of radiation than on the ground and they are prone to skin cancer, so, is there any way of reducing the amount of radiation for pilots?

Broadly speaking, radiation exposure can be mitigated in three ways: Time, Distance, and Shielding.  Two of these mitigating factors can't really be improved: Distance and Time.

For distance, the radiation exposure concern for commercial jet pilots (and travelers)is generally related to cosmic radiation and ultraviolet radiation from the sun. The sources are already quite distant, and the practical distances we can achieve on Earth won't make any appreciable difference here, so we can neglect distance.

Time (duration of exposure) is already somewhat limited by the duration of flights, but the cumulative effect over multiple flights is what we're generally concerned about when we discuss "pilot's radiation exposure".
As their career requires them to fly, and the nature of jets means they'll be flying at high altitude there's not much that can be done with time, except perhaps having a very short career or not accepting a large number of flights. These options are not economically attractive if flying is your career.

That leaves shielding. Pilots sacrifice the benefit of shielding (from the Earth's atmosphere) as they climb: The atmosphere is less dense and there is less of it between the pilot and the background radiation, therefore their exposure is increased.
It's here that improvements can at least theoretically be made: The pilots and passengers already gain some shielding from the structure of the aircraft, but not nearly as much as 30,000 feet of atmosphere provides. The aircraft could be constructed with additional radiation-shielding materials (lead foil for example, and UV-attenuating tints in the windows) but doing so would add a significant amount of weight.

As with most radiation shielding situations it ultimately becomes an economic trade-off: You implement shielding to bring the exposure (dose) down to an acceptable level given the time and distance constraints you're working within.
The additional dose received by pilots is already extremely low, and adding shielding to reduce it further would not give a huge increase in safety. The costs (in terms of aircraft design, construction, and operating cost to carry the additional weight) would exceed the cost of treating the relatively minor complications such as skin cancer which may result from the additional exposure over a lifetime career of flying.

If all of that was too much to read, the short answer to your question is "The best way to mitigate increased radiation exposure from flying is to remain at low altitudes." (Similar to how the best way to mitigate the increased radiation from living in Denver, Colorado at ~5,000 feet above MSL is to move to New Orleans, LA at 7 feet below MSL.)

The next best thing would be to fly less frequently or on shorter legs (to reduce the duration of exposure).


Switching careers from physics to aviation The main question is whether the background in the (scientific) field of applied physics and engineering can help one to start a career in aviation (to do it for living)?
It seems impossible and not worth trying, because it looks like many airmans start flying from the very beginning of their lives. After 15 years in the air they are (al least looks like) mature pilots that would be chosen to be hired somewhere instead of "that freshly switched street bum".
On the other hand, that sort of fundamental education and some years of work in the field may pose some advantage. Does it, really? If yes, how can it be exploited?

It's one of those things about the flying game that the actual details of previous education and experience outside of aviation count for relatively little, other than what they may indicate about someone's personality, worldview and leadership potential going forward.  This is because the knowledge base and skill set are unique to the trade.
I used to know a Capt of a major carrier who was on a selection board, and he told me once that the only real reason airlines expect a university degree is that it provides a higher than average probability that a candidate will be able to handle the firehose flow of information that a pilot has to deal with on an initial type course.  What the degree was actually for was not that important as long it was demanding to some extent (not those "XXX studies" degrees).
If someone is hiring a pilot, they want to know about flying experience, personal attitude, character, and very importantly, leadership potential (since in the long run they are expecting the candidate to be in command of a crew at some point).  Previous non-aviation experience that establishes strong leadership potential (the leadership ideal fostered by Crew Resource Management theory specifically) probably has a stronger effect on your desirability as a candidate that any particular technical background.
Now, if you get into a flying career and at some future point, where you have ample flying experience, you apply for a job posting for, say, a production test pilot with an OEM, or something similar at an airline, which is likely to have a dual engineering/flying function, then the physics/engineering background might count for quite a lot.
But at the start, it mostly indicates to a potential employer that you have an above average ability to absorb information, so it can't hurt, but don't expect much more than that.


Why do all new European fighter jets have delta wings? Why do all new European fighter jets - Typhoon, Gripen, Rafale have delta wings? As I know, they were all designed separately. And they are not new either.

Is there any particular advantage that caused the Europeans to choose to do it like it is? Is it because of traditions? Or do they use the same software? (cheeky grin)

No, they were not designed separately. They were designed by people who had all participated in collaborations before. The origin was the research into unstable configurations performed by MBB in Germany in the late 1970s by a modified F-104, the control configured vehicle F-104 CCV.

F-104 CCV (picture source)

As a result, MBB designed the Taktisches Kampfflugzeug 90 (or TKF-90), the first design of an unstable delta canard which promised unmatched maneuverability. Since Germany could not afford to develop the aircraft all by itself, collaborations were started with both Dassault and BAe, so that French and British engineers could learn of the advantages of this layout.

MBB TKF-90 concept (picture source)

First, BAe collaborated with MBB and joined the TKF-90 design, resulting in the European Collaborative Fighter proposal, only to continue on their own with two delta canard designs of their own, P.106 and P.110. P.106 had one engine and one vertical tail while P.110 had two of both, like the TKF-90. P.106 was rejected by the RAF, but went into a collaboration with Saab and eventually became the JAS-39.

To be fair, the first company to build and fly a closely-coupled delta canard was Saab with their Saab 37 Viggen. Saab has a long history of innovative work, beginning with ejection seats in 1942 and sweptback jets in 1948.

Saab 37 Viggen (picture source). In contrast to the TKF-90 it was an aerodynamically stable layout.

Meanwhile, MBB collaborated with Dassault in the Future European Fighter Aircraft (FEFA) program, so the French side learned of the advantages of a delta canard. Eventually, the French wanted less air-to-air capabilities and a smaller aircraft for better export chances, and the remaining FEFA partners continued in the European Fighter Aircraft (EFA) program which resulted in the EF-2000, while Dassault went it alone with the Rafale.

The EF-2000 is hampered to this day by this heritage. Its wing area was decreed by Maggie Thatcher and Helmut Kohl to be no more than 50 m² when a 60 m² wing would had resulted in a much more capable design. Next, the British engineers insisted on a straight leading edge, ignorant of the fact that only a cranked delta would provide good post-stall pitch characteristics. They also refused to accept a faceted design, and the German side could only rescue the "smiling intake" in order to reduce the radar cross section of the EF-2000 somewhat.

"Smiling intake" of the EF-2000 (picture source). The curved contour avoids corner reflections of electromagnetic waves.

And don't get me started on the odd location of the airbrake: On the center fuselage where it is least effective at high angle of attack and will blanket the single vertical tail. Designed by a committee with too many British engineers.


Can I be a pilot now considering the new advancements in color vision lenses and glasses? I have always wanted to be a pilot but I am red/green color deficient. I passed all other physicals and can easily tell the difference between red and green. I only discovered I had a deficiency after I failed the Ishihara Plates Test (the one with circles of dots with numbers). So I opted for Military Police instead of flight school. However, now color vision contact lenses and glasses are available with a 100% success rate after testing with the Ishihara Plates Test. Does this open any new doors for color deficient applicants in flight schools? I can't find anyone that has answers. Thank you.

According to FAA guide for Aviation Medical Examiners:

F. Color Vision Correcting Lens (e.g. X-Chrom)
Such lenses are unacceptable to the FAA as a means for correcting a pilot's color vision deficiencies.

However, you have the option of taking other tests for color vision. It would be better to talk with your physician or the medical examiner about this.


Why does the autopilot disengage even when it does not receive pilot input? After having read the disturbing

https://en.wikipedia.org/wiki/1999_South_Dakota_Learjet_crash

I'm left with the question as to why the computer allows for the autopilot to be disengaged when there is no pilot input.

Why doesn't it engage the stick shaker and alarm as normal, but maintain control until pilot input is received, or require the pilot to manually disengage the autopilot?

I'm not a pilot, so I'm sure there is good reasoning behind this. However, from my own naive perspective this is why it seems foolish to automatically disengage the autopilot:

This is what happened after the autopilot was disengaged:

"The target is descending and he is doing multiple aileron rolls, looks like he's out of control...in a severe descent, request an emergency descent to follow target."

Imagine that the crew did regain consciousness, they would find themselves in a disorienting situation, with an aircraft possibly damaged from aerodynamic stress when approaching mach 1 in an uncontrolled nose dive. This, compared to the autopilot simply maintaining attitude as best it can.

Until finally, this: "the aircraft hitting the ground at a nearly supersonic speed and an extreme angle."

The alternative being, with no pilot input that the aircraft would have maintained a somewhat stable attitude, deploys its landing gear, flaps, and prayed for the best -- that there just happens to be a fairly smooth piece of land, with no major obstacles in the way?

Now, I'm aware that all six on board were dead before the plane crashed. That doesn't mean there are no situations where a controlled crash landing is not preferable to an uncontrolled crash.

I'm not an avionics software engineer, so forgive me if I don't appreciate the complexity of the task -- but as a software engineer and someone with an IT education it seems to me almost trivial to extend the functionality for the aircraft to accommodate for this scenario with a mostly hard-coded procedure---yes, blindly landing at whatever is there and hoping (and with the system being extended with visual processing, perhaps, in the future). While I'm not even going to sketch a full proposal for such an extension here, it is part of my motivation for asking this question in the first place, so I'm simply mentioning it as that.

I can also mention, although I'm sure anyone qualified to answer this question will know about this case (and know it far better than I do), the Cornfield Bomber https://en.wikipedia.org/wiki/Cornfield_Bomber so if this is possible without any help from the computer, surely it would be possible with help, even from a computer that only has basic instruments (altitude, attitude, etc.) and no vision, yet simply attempts it "blindly" as far as visual processing is concerned.

Please keep in mind that I'm under no illusion that the plane will land without a scratch. This is a game of statistics, such as all safety procedures, and it seems (naively, I'm sure) that this might increase the chances of survival by some (probably slim) margin.

My own attempt at an answer:

I can only imagine that the reason such functionality doesn't exist, is because it is so rarely useful and considered too much of a curiosity. However, other crashes that also appear to be highly unlikely in general, have seen changes enforced in the aviation industry. So this isn't really a good answer.

The only other thing I can think of, is the omnipresent fear of AI. The idea to implement some AI, that could potentially, when given full authority of the plane, glide it into a building unintentionally, is just unthinkable for obvious reasons. While I sympathize with this view, I don't see why this is more likely than it happening with a plane flying without such a simple AI---both the AI and the completely uncontrolled plane would be flying just as blindly, both at risk of hurting innocent bystanders. The only difference is that the AI assisted plane flying autonomously (despite mostly blindfolded) does have a marginally higher chance of allowing for some survivors.

The "autopilot" is a fairly basic control system. Usually it is composed of just a few components (logically speaking) like a wing-leveler, heading mode, and altitude mode. The autopilot can control the aircraft usually through servo's connected to the control cables or through the hydraulics. External systems can feed into this to do things like follow a descent path, follow GPS/VOR routes, etc. The autopilot itself is basic.

The autopilot is designed to fly an aircraft that does not otherwise have any other issues. The autopilot is not designed to fly outside of normal operating circumstances. This means that when some kind of abnormality is detected (usually through the autopilot hitting its programmed limits) it will automatically disconnect.

In the Learjet case you cited, the autopilot continued to maintain altitude after the engines failed, but because maintaining altitude without engines means your speed will decrease, the autopilot disconnected before the aircraft stalled rather than fighting the pilot through a stall. It assumes that it is safer to automatically hand-off than require the pilot who is now trying to stabilize the aircraft to also have to worry about disconnecting the autopilot.

Most autopilots give some kind of warning that they've disconnected. This can be things like a chime, voice alert, stick shaker, etc. It's the autopilots way of saying "I've reached the limits of what I can control, you need to take over now". Otherwise it could potentially make a situation much worse.

The cornfield bomber was not on autopilot when it crashed. It just regained stability as a result of the ejection and remained on a fairly level (but descending) path until it bellied into a field (and continued to run/move for quite some time).


During an engine failure should I deploy 10° of flap or keep it clean? Imagine I have an engine failure in cruise flight with a Cessna 152 or 172.

Should I select 10° flap to increase glide angle?
Would it give me more range to reach safety?

You keep it clean: adding flaps adds drag. You can see this in Section 3 of the Cessna POH, which includes a Maximum Glide (distance) diagram. In the C172S POH that I checked, it notes that maximum distance is achieved with:

  SPEED 68 KIAS
  PROPELLER WINDMILLING
  FLAPS UP
  ZERO WIND

(A tailwind would extend your range, but only in one direction.)

Two other points worth noting:

If the engine failure also caused an electrical failure then you won't be able to use the flaps anyway (in models with electrically operated flaps)
You might want to reduce your gliding distance if the best landing spot is relatively close by, and extending flaps is one way to do that (along with slipping, S-turns or other maneuvers, and extending the gear)


Why is the 787 tail cone made out of titanium? In this question there is a drawing of a 787 that shows that the tail cone is made of titanium.

Why is such a heavy-duty material like titanium required for the tail cone?

I do not see how there could be any significant loads or reasons for excess temperature there.

Whenever you see titanium being used on aircraft, look for heat sources. The metallic alternative aluminum is usually lighter and much cheaper.

In most commercial aircraft the APU (Auxiliary Power Unit) is in the tail, behind the rear pressure bulkhead and the empennage.

(modified from aerospaceweb.org)

The APU is a small turbine and its exhaust gases are very hot (I don't have exact data and it depends on the APU model, but the exhaust temperature should be somewhere in the range between 400°C and 800°C). Aluminium has not only a low melting point (660°C), but its mechanical properties degrade fast once it gets hot. On the other hand, titanium has a higher melting point (1668°C) and still performs very well at high temperatures without significantly loosing strength.

While carbon fibers don't lose their mechanical properties at high temperatures, the resin types used as a matrix are very far from being able to withstand these temperatures. Even PEEK, probably the best resin for use at "high" temperatures, has a glass temperature of 143°C (melting point at 343°C). This makes resin-based composites inappropriate. An alternative would be using ceramic materials as a matrix (CMCs). However, the simple geometry of the tail cone probably makes the production with titanium cheaper than with CMCs.

Here's an image of the cone (source: flight.org):


What is a flying fuselage aircraft (FFA)? I'm fond of ultralight flying and stumbled over the SF-1 Archon site.

Specifications for more details.

I found it very appealing as an ultralight and feel like flying it even though i don't have any prior experience with pusher configuration.

I have never heard of the FFA (flying fuselage aircraft) concept so far. My knowledge is rather limited to basic conventional aircraft where the fuselage is considered to neutral by design.

Can someone expand on it please?

I found this off the website after some searching:

  The advantages of the flying fuselage aircraft (FFA) category,
  compared to conventional aircraft (CA) category and flying body
  aircraft (FBA) category, are the following:

  In conventional aircraft design, the fuselage is aerodynamically
  neutral and joins only the separate parts of the aircraft. As the
  wings grow the buoyancy grows as well. In the flying body aircrafts,
  aerodynamic lift is produced only on the outside of the fuselage and
  the wings, which comprise a unite body. As the fuselage and wings
  grow, the generated lift becomes greater. In the flying fuselage
  aircraft the extra lift is generated from the interior of the fuselage
  and from the whole aircraft in and out. Thus, maximizing the full
  extent of the aerodynamic performance of the aircraft. Practically,
  the new category of the flying fuselage has the following advantages
  compared to the other categories above. i) because of the greater
  generated lift ,the aircraft is designed smaller in size, in order to
  have the same performance as its peers.

  ii) due to the smaller dimensions of the aircraft, it occupies less
  space and needs a smaller hangar. (cost reduction).

  iii) the most important advantage is that during the flight in
  conventional and flying body aircrafts, stability comes only from the
  main wings dihedral, as well as the size of caudal. The flying
  fuselage design acts as a funnel and provides extra stability to the
  aircraft, making the air mass passing through the fuselage in a column
  of air (air shaft). This is maximizing the stability of the aircraft
  in all angles and phases of flight. Source

So what I think what they're trying to say is that the body generates lift as well. It sounds mostly like something like a blended wing body or lifting body in my opinion as a meeting point between a conventional and flying wing aircraft. In any case, the term FFA seems very uncommon and not widely used.

SF-1 http://www.aerosports.gr/images/photos_gallery/archonSF1/4.jpg

The closest similar thing I've found was this aircraft. The F-22 Raptor which it seems to closely mimic is not considered a flying wing nor a blended wing body, and after looking at the fuselage I remained a little unconvinced that it generates substantial lift as a body due to the substantial upper structure and lower structure.


What is Special VFR? Why would a pilot request it? I have heard about Special VFR many times but never understood this concept. What is it and when is it used?

Special VFR is used to leave or enter a control zone coming from or continuing the flight in airspace G (Golf), when the weather minima for VFR flight are not met within the control zone, but would be met in airspace G.

Example: Airspace G (Golf) requires a visibility of 1.5km and aircraft need to remain clear of clouds. Airspace D (Delta) requires a visibility of 5km and 1000ft vertical and 1.5km horizontal separation to clouds.

If the weather report would show a visibility of 4km/4000m and a cloud base of 1400ft, the flight would be allowed in airspace G but not in airspace D.

Requesting Special VFR within a control zone will drop the VFR weather requirements to the values required for airspace G, so flight may enter or leave the controlzone. The lower visibility requirements are compensated for in the control zone by stricter separation requirements between aircraft. SVFR is separated to SVFR and IFR traffic.


Why are Gatwick's runways too close together? Gatwick Airport has two runways (08L/26R and 08R/26L), but they are only 200 metres apart - too close (by just ten metres) to allow simultaneous operations on both runways.  As a result, usually only 08R/26L (the older, more southerly, and slightly longer of the two) is used as a runway, with 08L/26R serving only as a taxiway except when 08R/26L is closed for some reason.

Given that Gatwick has plenty of space available that could have been used to put 08L/26R ten metres further north and thus allow simultaneous operations on both runways, and that Gatwick is, and was, bursting at the seams with the amount of traffic it has to fit down 08R/26L, why was the new runway built just slightly too close to the original?

Historically, Gatwick had only one runway (08R/26L) with a taxiway to the north, but this obviously would cause problems if that runway was out of use for any reason - emergency, scheduled maintenance, etc.

In 1979, the taxiway was upgraded so that it could be used as a runway when the main runway was out of use. Since this used existing infrastructure, the locations were obviously fixed.

However, at that time the then owners of the airport (BAA) agreed with West Sussex County council that the second runway would only be used when the main runway was unavailable. This was to protect the interests of the airport's neighbours. With this agreement in place there was no incentive to address the issue of separation. The agreement was set to run for forty years, and expired recently on 13th August 2019.

With the imminent expiry of that agreement, the airport is now exploring ways to  bring that second runway into use. One suggestion is to widen the existing main runway southwards, allowing the centerline to be moved south and increase the separation.

Source: The Independent, 15 October 2018


Would shutting down the engine have prevented the Atlantic Southeast Airlines Flight 2311 crash? In the crash of Atlantic Southeast Airlines Flight 2311, a worn propeller quill caused the propeller blades to go flat, which created enough drag on that side of the airplane to make the aircraft uncontrollable.

If this were to happen in flight, and the bad engine were completely shut down, would that reduce the drag enough to recover control?

Perhaps in the case of 2311, they might have been too low and too late, but in general, can this type of failure be recovered from? It seems that if the propeller were not being driven at high RPM by the engine that the drag might be less severe.

The description of the accident says the propeller went to a flat pitch of 3°, which is still positive. At such angle, the air is trying to spin the propeller in the same direction as the engine, so the engine running helps the propeller spin. Only if the propeller went all the way to negative pitch would the engine be the air trying to spin it in opposite direction and therefore produce additional drag, but it appears that propeller was not built to allow negative pitch.

So I don't think it would have helped. It probably wouldn't have made much difference in the very flat pitch.


Is there a tool to plot locations within X nm of a position? I'm looking for a tool to allow me to see what is within X nms or X hrs of my base airport. Is there such a thing?  I remember a small airport I flew to once had a large map with a string attached to a pin located at the airports location on the map.  There were concentric rings from the location stating 100/200/300....nm. I'm basically looking for something like that such that I could explore and look for locations that are off my normal radar of places I would typically visit.  I typically use landings.com for baseline flight planning but you need an origin and destination. It doesn't look like it allows what I'm asking for.

I'd even be happy if there was a hack for google maps etc. to do what I'm asking.

At least a couple of tools exist to search for airports beyond a certain distance from your departure point. You didn’t specify, so I will use mine: KHUA.

Using gcmap.com, search for near:KHUA beyond:50nm within:70nm to get a list of airports in the specified range.

To plot some of them on a map, place a few of those in a comma-separated list, e.g., KHUA,KGAD,KBHM,KSYI,KBNA,KAYX,M22,TN50,KJFX,KMRC,KAPT,KPYP,1M4,M22, and select the Map tool. Plot range rings with one or more lines in the Ranges box under Map Controls. I used

  50nm@KHUA
  70nm@KHUA

Click the Draw Map button to update your map.

The final result will resemble the image below.


What is the difference between flutter and vortex induced vibration? During flutter, the airfoil oscillates with a large amplitude, which generates vortices at the wake. In vortex induced vibration (VIV) the oscillations of the airfoil are caused by the shedding of vortices. Both flutter and VIV have airfoil oscillations and vortex shedding.
How are they different other than the cause and effect relation? And also how to distinguish which one is the cause and which one is the effect for a case where we don't know beforehand whether it is flutter or VIV?

Flutter and vortex induced vibrations (VIV) are both dynamic instabilities arising from the interaction of unsteady aerodynamic, inertial and elastic forces. They both extract energy from the air stream to persist.

Instead of perceiving the interaction as aerodynamic forces causing structural motion or structural motion generating aerodynamic forces, it is more meaningful (and realistic) to describe it as a coupling, e.g.,  typically described as coupled differential equations, and observing the differences in how the aerodynamic forces are generated and its components.

For VIV, the wake instability that generates the alternating shed vortices (von Karman vortex street) in turn generates an oscillatory lift coupled with the structural oscillation. So, the wake instability and unsteady effects of flow separation dominate the oscillatory aerodynamic forces.

Flutter does not have to describe a dynamic instability associated with a fluctuating wake, e.g., panel flutter is the dynamic interaction and instability arising out of the out-of-plane motion of an aircraft panel in relation to surface fluctuating pressures. However, stall flutter does arise from flow separation and its resulting unsteady wake.

Wing flutter is the dynamical instability arising from the unsteady aerodynamic forces (including the shape of unsteady wake) coupled with the structural dynamics, however wing flutter does not require massive oscillatory flow separation as with VIV. For attached flows (unstalled), wing flutter could exhibit flutter (at a high enough freestream velocity, i.e., flutter speed) due to the resultant phase difference between the generated aerodynamic forces and structural oscillation creating a positive feedback. The time-varying shape of the wake still plays a role for wing flutter, e.g., the role of the Theodorsen function for unsteady aerodynamic lift generated by structural motion.


Puzzled by description of AoA malfunction theory on recent Lion Air accident The theory for the recent Lion Air accident states that the AoA sensor malfunctioned and the airplane systems commanded nose down.
Boeing also stated this occurs when the autopilot is disabled. The implication is that the pilots had no input to disable nose down command.
Is this inference correct in the B737-Max?

The Operations Manual Bulletin put out by Boeing suggests that this is a trim runaway event.  Airspeed and altitude measurements are affected by the angle of attack of the airplane.  The indicated airspeed will be lower in a high angle of attack situation.  The accident airplane was reading a higher angle of attack than reality due to a malfunction of some kind.  The new avionics in the Boeing 737-MAX correct the airspeed measurement for angle of attack so airspeed was reading higher than what it should have been.  As a result the automatic trim, which is set to keep a constant airspeed, kept trying to lower the nose since the reported airspeed was too high.

The 737-MAX Operations Manual Bulletin included procedures to disable the automatic trim.  This runaway trim event occurred during the 3 flights before the accident flight but maintenance was unable to fix the problem.

More information on the accident can be found at the Aviation Herald.


Under what conditions can a pilot log simulated instrument time? Can a pilot log simulated instrument time with these conditions and what regs would justify this:

VMC
Safety pilot on board
View limited device
VFR-only aircraft
Unapproved instrument navigation devices (ie. handheld NAV/COM)
Location USA

Say the pilot had a copy of Foreflight and a handheld NAV/COM with ILS capability. Aircraft is has typical VFR 91.205 equipment.

It is simply a VFR flight, you need to meet normal VFR requirements plus a qualified safety pilot to watch outside for traffic. I assume this aircraft has the minimum IFR flight instruments not including navigation, and is being used to practice basic instrument attitude skills, otherwise I don't know what the point would be. Flight by reference to instruments implicitly requires instruments to reference; a handheld device can not provide gyroscopic data as these inherently need to be fixed to the aircraft frame.


What if you refuse to fasten your seatbelt? As a passenger, what happens / can happen if you refuse to fasten your seatbelt when you are told to, either during take off/landing or (bad) turbulences?

I've recently read a Facebook post that supposedly described such a situation. It didn't give many details, so that's why I'm here.

In the US it is an offence under federal law.
A loose 180lb/80kg projectile inside an aircraft is a threat to other passengers during turbulence, in the worst cases of passenger misbehaviour cabin staff can and have forcibly restrained passengers and/or diverted to a nearby airport to have the passenger deplaned and sometimes arrested.
Seven Ways to Get Kicked Off a Plane
Family kicked off plane

A 3-year-old, who refused to use his safety belt, caused a flight to be delayed after his father could not get him locked in his seat belt on board an Alaska Airlines plane.
The pilot returned to the gate on Saturday and asked the father and child to get off the plane.

Why you need to wear a seatbelt

For passengers who refuse to wear seatbelts when the sign is illuminated and who are disruptive to the crew, the FAA can impose a maximum fine of $25,000.


Why do wings of passenger jet go dark during a flight? Why do certain areas on passenger jet wings go dark during a flight? This effect is observed on high altitude where temperature is low. When airplane descends, wings return to their initial color.

Wing during a flight on high altitude.

The same wing before landing.

I've noticed this effect in several flights on different aircrafts. It is clear that these areas are covered with other coating, but what is the purpose of this?

As DeltaLima said, the change in brightness is probably due to the difference in lighting. The first picture is above the clouds, so the air is clear and the light is primarily from the sun. The second picture is in the clouds, so the air is moist and the light is much more diffuse, coming from all directions. This diffuse lighting and the moisture on the wing surface help to reflect more light. You can see this in the already reflective leading edge as well. In the first picture, mostly the darker sky is reflected, but in the second picture, the brighter clouds are reflected. The reflected light will be more evident in the darker areas than lighter ones.

Regarding the materials, they represent different parts of the wing. The darker section represents the main structure of the wing, so the surface is made of metal for strength. The sections around it do not carry as much load so they are made of composites to save weight. The metal conducts heat better, so it will tend to condense more moisture than the composite section, as the aircraft is descending from cold, dry air into warmer, moist air.

The surfaces do seem to have different finishes. This is probably related to the different types of material there.

Those pictures illustrate your question very well. I don't specifically remember noticing this sort of thing myself, but I will see if I have any myself showing the same thing.

Also... anyone know what plane this is? The pointed ends of the shock bodies, the VG's, and the static wicks outboard of the aileron make me think a 737 classic with winglet retrofit.


Where can I find canonical examples of radio communications at non-towered airports? I'm trying to find any canonical examples of radio communication patterns at non-towered airports. The FAR/AIM has very little in terms of sample announcements, etc. The AC-90-66B (https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_90-66B.pdf) doesn't offer much either. The best resource I could find so far is the "Say Again, Please" book by Bob Gardner, but I'm trying to find the guidelines from the "FAA's mouth."

What you're looking for is AIM 4-1-9(g)(6), recommended self-announce phraseologies. The self-announce phrases states position, altitude, climb/descent, among other things depending on the situation.

6. Recommended self-announce phraseologies:
It should be noted that aircraft operating to or from
another nearby airport may be making self-announce
broadcasts on the same UNICOM or MULTICOM
frequency. To help identify one airport from another,
the airport name should be spoken at the beginning
and end of each self-announce transmission.
(a) Inbound
EXAMPLE−
Strawn traffic, Apache Two Two Five Zulu, (position),
(altitude), (descending) or entering downwind/base/final
(as appropriate) runway one seven full stop, touch−and−
go, Strawn.
Strawn traffic Apache Two Two Five Zulu clear of runway
one seven Strawn.
(b) Outbound
EXAMPLE−
Strawn traffic, Queen Air Seven One Five Five Bravo
(location on airport) taxiing to runway two six Strawn.
Strawn traffic, Queen Air Seven One Five Five Bravo
departing runway two six. Departing the pattern to the
(direction), climbing to (altitude) Strawn.
(c) Practice Instrument Approach
EXAMPLE−
Strawn traffic, Cessna Two One Four Three Quebec
(position from airport) inbound descending through
(altitude) practice (name of approach) approach runway
three five Strawn.
Strawn traffic, Cessna Two One Four Three Quebec
practice (type) approach completed or terminated runway
three five Strawn.

Examples shown are from the Aeronautical Information Manual. I hope that helps!


What does it mean to fly a procedure turn? So, I'm flying IFR to Newport (KONP) for the ILS RWY 16. There's an aircraft on the approach, so I'm cleared direct BUHRS at 5000' to enter the hold as published.

I get to BUHRS, I turn outbound on the hold, and am "cleared for the approach". (Note: Not "straight-in").

So, what is my next step?

AIM 5-4-9 says I'm required to fly the procedure turn, but I can't find a definition of what that actually means (i.e. do I have to overfly the waypoint to "start" the procedure turn, or does it just mean remain in the protected area?). The options seem to be:

1) Turn back to BUHRS, overfly BUHRS, turn right (ending up exactly back where I am right now), intercept the localizer outbound, descend to 2600.

2) Intercept the localizer outbound, descend to 2600.

If #2 is correct, then there's an additional point of consideration. 5-4-9a1 says I have complete discretion in how I fly my procedure turn. Certainly turning immediately inbound fits within that discretion (instead of turn right, intercept outbound, turn left, turn left, turn right, intercept inbound). Or, what about continuing to fly outbound by heading for a minute then turn inbound and intercept the localizer?

A simplistic reading of the AIM seems to indicate #1 is correct. I asked AOPA, they say #2 is correct.

Is #2 correct? If it is, wouldn't an immediate turn inbound also be correct? What is the definition of "procedure turn"? Does it require flying over a fix to "start"? Or can you be anywhere in the protected area?

The easy solution is to ask for a straight-in clearance, but assume you're not in radio contact or your request is denied.

In my opinion, as soon as ATC clears you for the approach, the holding pattern at Buhrs is cancelled (i.e., is no longer required - 1 min. leg cancelled). Begin a descent to no lower than 2600  and turn inbound as soon as you are far enough north of Buhrs (remaining within 10 NM) that you can comfortably descend from no lower than 2600 to  no lower than 2100 after established inbound on the localizer. (I would plan to be reasonably close to 2600 at the point of intercepting the localizer inbound so that I would not find myself above the glide slope).

Remain at or above 2100 until intercepting the glide slope and finish the approach.

As you have pointed out in your question, the "point," "type," and "rate" of turn is left up to the discretion of the pilot.  Since it is perfectly legal, and most importantly, safe to do a racetrack pattern (on the PT maneuvering side) and that is exactly the position you are in, this would be the best option.

The fact that your approach clearance came shortly after you had entered the hold (when you were turning outbound) does not obligate you to go back to Buhrs and then officially begin the approach by turning outbound again (45 degree procedure, racetrack procedure, 80/260, etc.).

Just tell ATC you are leaving 5000 and beginning the approach.

From the AIM para. 5-4-9, sub para 1:


Why don't planes have a reverse propeller as air brakes? When I first heard the word air brakes it came to me that maybe the engine start rotating in the opposite direction for that, but since that's not possible, why can't we have an extra engine for air braking?

Did I just invent a new braking paradigm?

Planes with a variable pitch propeller can have a pitch range which twists the blades such that they provide reverse thrust. This started to become a common feature on high-performance airplanes in the 1930s.

Not all variable-pitch propellers can produce reverse thrust, however. The constant speed props on small propeller aircraft usually don't, because the energy of the plane after touchdown would be too small to justify the added complexity. On big airplanes which need short landing distances (the C-130, for example), they are a standard feature.

In 1936, Heinkel produced a sleek dive-bomber, complete with retractable landing gear and a reversible pitch propeller which could be used as a dive brake. The He-118 was test-flown by Ernst Udet, who did not pay attention at the briefing and went on to overspeed the airplane in a dive, destroying the prototype in the process. Thus, the clumsy, fixed-gear Ju-87 was chosen to be the "Stuka" and the He-118 would end as an inspiration for Japanese aircraft designers.

The Pilatus PC-6 Turbo Porter is a favorite with skydivers because it can put the propeller into reverse even in flight. This allows for spectacular descents and enables it to be safely back on the ground before the skydivers it dropped a moment before have landed.

As usual, Wikipedia covers the topic well, so here ist the link.


Why are movable rocket thrusters not used in airplanes? If an engine fails in a passenger airplane, why can't it have movable rocket thrusters in the wings to help safely land the airplane?

Any time the question is "why don't we have...", the answer is almost certainly in the trade-off between weight, maintenance cost, fuel cost, & utility. If it weighs a lot, needs maintenance, burns fuel, and will only be useful once a decade, then it just is not productive.

Putting rocket thrusters on a plane will be heavy, meaning fewer passengers, or less fuel or cargo on board.   All that extra weight has to be flown around, requiring fuel.  They would need regular maintenance checks, which is another cost.   And they would only be useful very, very infrequently (on most planes... never).

So, safety issues completely aside*, it is just impossible to justify adding new equipment for a once-in-a-lifetime scenario, which can be better managed with good maintenance, good training, and good planning.

This same line of reasoning goes for "why don't more airplanes have parachutes", "why don't planes have anti-missile systems", "why don't planes have airbags", and many other random items.

*Safety issues are a big deal with rockets.  Rockets are a controlled explosion.  What happens if that explosion is not controlled?  What happens if the rockets are triggered by accident, or blow up all at once?  Even if rockets passed all the tests of utility vs. costs, they would still increase risks to the plane, rather than decreasing it.


What is the ICAO equivalent of /G in a flight plan? How should I fill out an ICAO flight plan if I have a Garmin GNS-430W WAAS certified unit? I file as /G in the US domestic format.

I have a GNS-530W, which is identical to your unit except with a bigger screen and I file ICAO with a G, B, and S, which are GNSS/GPS, LPV, AND VOR/ILS, respectively, to indicate the equipment I have on board. Technically just the G would be sufficient but I list all I am capable of to assist ATC in routing me most effectively or in the event of an emergency.

This would be entered on the form as "G, B, S"

Here is an excellent article explaining the new fields and codes for filing ICAO as the FAA domestic flight plan form comes to an end soon:
Filing ICAO Flight Plans in ForeFlight


Why are aircraft turbine blades made of nickel alloys? Why are aircraft turbine blades made of nickel alloys? What is the advantage of using them? Why did they replace steel alloys for turbine blades?

How to overcome failure cases of turbine blades?

Not all turbine blades are made of nickel alloy, some blades are made of such family of alloys but clearly not all. Some blades are actually made of ceramic materials.

The turbine is always located after combustion chamber and the temperature which the first stage of turbine blades is able to resist is a proof of high technology engine. Those blades are exposed over to 2000ºC; the melting point of steel is around 1100ºC, and nickel can go much further up to 1700ºC. Ceramic can go even further. Note that there is also a significant difference between external flow temperature and surface temperature.

Using a high melting point material is one way to solve the problem, there are also ways to reduce the effective temperature over the surface of the metal like using film cooling.

In the figure I introduced above you can see holes in the blade, where "cooling air" (maybe at 400ºC) flows out of the blade creating effectively a film that goes around the blade protecting (cooling) it from external temperature.

However a metal exposed at a high temperature (below the melting point) is not behaving in the same way as at normal temperature. There are some phenomena affecting the materials like creep. When a material is exposed during long term to high temperatures close to the melting point and high stress at the same time (this is important) it starts suffering deformations that lead to a failure of the metal.

So nickel alloys, apart for having a higher melting point are also having one of the best behaviours in creep environments.

The last stages of the turbine rotors, and more easily stators (less demanded in stress) are less exposed to creep conditions and are not needed to be manufactured in a nickel base alloy.

Just to add as well, in order to reduce creep another approach followed (combined with previous) is to solidify the metal ensuring having a single crystal metal (instead of being a polycrystalline metal). This is utmost art of material engineering (from my point of view).


Why is this Instrument Approach NA for certain radials, yet it depicts a feeder route for those radials? The RNAV (GPS) 28 at Tampa Intl (KTPA) says

Procedure NA for arrivals on PIE VORTAC radials 356 CW 157

That seems to mean the approach is not available for anyone generally northeast of the PIE VORTAC. Why is there a feeder drawn on radial 085, clearly within the 356 CW 157? Moreover, the whole approach procedure is within those radials east of PIE. Does the NA comment simply mean a pilot must be coming from the west side of PIE when they request the approach?

Your confusion may stem from the way you are viewing the instruction not to use it for arrival on the radials 356 to 157. If you were arriving on the 356 Radial of the PIE VORTAC, your course/track (and/or heading in calm winds) would be 176°. If you were arriving on the 157 Radial of the PIE VORTAC, your course/track (and/or heading in calm winds) would be 337°. If you were arriving on the 85 Radial of the PIE VORTAC, your course/track (and/or heading in calm winds) would be 265°. All of these arrivals would necessitate a hard, sharp turn at a potentially steep bank angle. This will need to be avoided.
You are able to use other routes to the Initial Approach Fix other than flying first to the PIE VORTAC. Like flying directly to the RUYKI waypoint as your first point on the IAP. This is especially valid since arriving on any of the above mentioned courses/tracks will place RUYKI in easy access of the pilot. This would be much simpler than trying to make that hard, sharp turn at a steep bank angle. Only minor adjustments from the arrival course/track at an appropriate distance from RUYKI would need to be made. This has the added benefit of reducing confusion and freeing up airspace from conflicting traffic.
If you are concerned with using the STARs as feeder routes, you would use the PIE VORTAC as your transition to the IAP from all STARs with endpoints West of KTAP. You would fly directly to RUYKI from all STARs with endpoints East of the IAP. If you have to lose altitude from your descent from the STARs, you would use the Hold en lieu of a course reversal to do so.


If planes can go faster, why don't airlines fly faster? I came across this page where a DC-8 set a record in 1964 for a 12h24m flight from Montreal to Tokyo. Last year I flew to Tokyo from Montreal and it took 9h from Vancouver (where I had a layover)

I suspect the answer is along the lines of "for safety reasons", but surely in the 5 decades since that record airplane design and safety protocols have improved such that today's planes can fly faster and safer.

Am I mistaken in that airlines today don't fly at the fastest the airplanes can ? If so why not ?

The key issue that determines the aircraft speed is economics. Airlines fly the aircraft that make most sense economically- which is rarely, if ever, the fastest speed possible (more speed equals more drag usually, which reduces fuel economy). More fuel efficient the aircraft is, better the range/passenger capacity, making airlines more money.

The top speed of the (subsonic) aircraft has changed only a little in the past few decades- most developments have been geared up towards improving fuel efficiency, not increasing speed (speed alone doesn't make economic sense to airlines; look at what happened to Concorde).

There is another issue here- most of the passenger aircraft fly in high subsonic (transonic) regime. As a result, the airliners are flown below the drag divergence mach number, beyond which the drag increases rapidly. This limits the aircraft speed.

As a related point, due to the high altitudes at which the aircraft are flown is that there is little speed range to chose from between the stall speed (lowest speed possible) and critical mach number (highest speed possible beyond which flow separates due to local supersonic flow). This limits the practical options available to the pilot.


What is the difference between deice and anti-ice? Most aircraft contain systems which are used to mitigate problems which could be caused by ice. This includes everything from a heated pitot tube to a wing leading edge heated by bleed air. These systems are usually referred to as either deice or anti-ice systems.

What is the difference between deice and anti-ice?

De-ice is a system that removes ice that has formed on a part.

Anti-ice is a system that prevents ice from forming on a part.

A heated leading edge(bleed air) is an example of an anti-ice system.

A inflatable boot on a leading edge is an example of a de-ice system.


How do I tell if class E airspace extends to surface or starts at 700'? I am confused about where class E airspace starts in the USA. If it has dotted magenta lines does it start at the surface? If small airport has round magenta circle but no dotted lines does class E start at 700'?

Source: FAA VFR chart.

The magenta dashed is from surface, the magenta gradient is from 700 ft. AGL, and the blue gradient from 1200 ft. AGL.


Is there something like an ignition key for planes? Is there something like an ignition key for planes?
Or could one "just enter" and fly away if they could?

The planes I have trained in (single engined Piper Cherokees/Warriors) do indeed have an ignition key, without which the magneto system (which drives the spark plugs) and the starter cannot be engaged. Without being certain, I would assume the same goes for other small GA aircraft.

When you get to airliners I have no idea whether there are keys for locking the controls - as the controls are much more complex, the keys probably won't be directly connected to ignition systems or starters, and I wouldn't be surprised if the primary security method is keeping doors locked.


Where to get flight dynamics for a flight sim model? Once, a while ago, I tried to create a Flight Simulator X model for an aircraft that I wanted a model of, but was soon overwhelmed by having to guess so much of the flight dynamics. Is there somewhere where I could get detailed information about the flight dynamics of aircraft without contacting the manufacturer, a pilot, or having the plane itself to run tests on? I mean for things like drag at different mach, drag coefficient created by the landing gear, lift coefficient created by the flaps, detailed stuff about the engines, etc.

Unfortunately I have no experience with how FSX models aircraft, but at a guess, it's model requires extensive experimental data from a real aircraft to truly get the right parameters.

And that's something no hobbyist is likely to be able to do. For that matter, it's pretty difficult for a pilot to do, since actually recording the relevant data is difficult, and some of what you need to know requires doing things with the aircraft you probably shouldn't do in most circumstances.

X-Plane's flight model and aircraft creation tool is far more forgiving. You still end up having to guess a lot of parameters, but they are generally less critical to basic handling.

All you really need to get a decent flight model out of X-Plane is a good set of reverence pictures, an eye for detail (so your model matches the geometry properly), and ideally the correct airfoil profiles and engine specifications.
(Primarily the thrust and power)
For the most part, good reference models and diagrams, and the information you'd find in the Pilot's operating handbook is enough to create a decent flight model in X-Plane.
It certainly won't be perfect, and you'll probably have to tune it, but it's a much easier task than getting that data needed for an FSX model.

I have the good fortune of being a student pilot, and as such I decided to attempt a model in X-Plane, and found that while it was far from perfect, (and needs a lot of improvement to be a 'good') model, it's behaviour was much closer to the real aircraft that I fly regularly than I was ever expecting given how much I had to guess.

I had to guess everything from the aileron deflection angles to the propeller geometry, wing airfoil choices and more, and still the resulting model was only slightly off from the real thing insofar as I know how the real aircraft flies.

I guess that's not an overly helpful answer in a direct sense for an FSX flight model, but I fear it just isn't going to be at all easy to find the information you need to make a flight model that isn't fundamentally broken in FSX, let alone accurate.

X-Plane is just far simpler to work with when you don't have a lot of information...

Whether that's worth the downsides of X-Plane (especially the consequences of switching if you already have a heavy investment in FSX), I don't know.
But it's worth keeping in mind if you are particularly fond of amateur aircraft design.

(It's even plausible to create fictional designs in x-plane for which no real-world data could ever exist in theory, and still get a good idea of how such a design likely would fly if it did exist.)

As for FSX potentially having better flight models in some cases? Maybe. But this is likely going to be the flight models of expensive add-on aircraft models that were made with the help of the manufacturer and pilots qualified to fly the real aircraft.

That's not going to help you any if you don't have access to those kinds of resources.

A hand-tuned model matched to exact real-world data may well work better than a physics based model if you have good source data.
But if your source data is lousy (as it is for most of us unfortunately), then the physics based model will be much more reliable most of the time...


What is qualitative relationship between surge line, stage characteristic and throttle characteristic? I have referred to standard author books and online tutorials but I am still quite confused about how the Stall and Throttle characteristics lead to Surge.

1.  Why and how does the throttle characteristic affect the compressor performance because as far as i know, the next consecutive element in an engine after a Compressor is a Combustor, and the throttle comes at last,after combustor and turbine,  assuming throttle is same as nozzle (if not please correct me).

Assume i am talking about turbojet engines and Axial compressor, just to have a picture in mind.

2. How does the throttle characteristic curves come out to be like that?

And why does the mass flow decrease when we throttle the compressor?

3. I am also unable to grasp the concept which causes the evil fluctuations in the flow during surge, which leads to reverse flow and damage of the components.

Source:- Hill Peterson- Thermodynamics of Propulsion.

Someone please explain the concepts as much as possible.

Since your question is divided in three parts, I do the same with my answer. First, however, we need to explain what the axes of the graph mean. The x-axis plots mass flow through the compressor, which is roughly equivalent to the tip speed of the compressor blades, and the y-axis shows the pressure ratio between entry and exit flow.

Throttle and compressor performance

The throttle regulates fuel flow, and this flow has to match the air flow. The limits are:

If fuel flow is too high: The combustion will create too much heat, so the turbine will be damaged.
If fuel flow is too low: Too little energy is added to sustain the current operating point. The engine will slow down.

If it is kept within those limits, the throttle will indirectly control the compressor speed and it's mass flow. More fuel flow will translate into higher turbine entry speeds, which will increase the torque produced by the turbine and speed it up. Since it is directly coupled with the compressor, it will see the same speed increase. This leads to higher mass flow and a lower fuel-to-air ratio in the combustor (relative to the state right after the throttle increase), such that a new equilibrium at a higher speed is established.

Throttle lines

For every pressure ratio the compressor will have a matching mass flow, and both move up and down in parallel. This is shown by the dashed lines. Depending on the blockage of flow in the turbine and the engine nozzle, different lines are shown for different grades of blockage. The solid stage characteristic line shows the limits within which the compressor will run, and a higher flow resistance narrows the range of speeds that are possible. The limits are determined by:

Lower limit: Here the compressor is run at the lowest possible speed for the given blockage, and the compressor blades run close to their maximum lift coefficient. When the blockage is increased, the flow over the compressor blades will stall and the pressure ratio will collapse.
Upper limit: Here the compressor blades run at high speed and a low lift coefficient. Running them any faster will not create enough pressure rise per stage, and again the blocking cannot be overcome.

Surge

Once the pressure rise per stage cannot be maintained (say, due to a stall of the flow over the compressor vanes), the high pressure air in the combustor will find it easier to escape at the front than to flow through the turbine and the nozzle. This leads to reverse flow and a sudden drop in combustor pressure, which in turn allows the compressor to reverse the flow and start pumping air back again. Now the pressure in the combustor rises again, until the whole process repeats.