10

It means that both Flight Directors are engaged: Flight Director (FD) Engagement The FDs are engaged automatically whenever the FMGC powers up. Ground Engagement The symbol "1FD2" appears on both PFDs. No FD bars appear on the PFDs. The PFD displays FD orders when a mode is active on the corresponding axis. The FCU windows display ...


10

The quoted explanation about "fail operational" and "fail passive" is correct, in that "fail operational" means the system will continue to function after an failure, and "fail passive" means the system will not misbehave after an failure. The exact number of autopilots required to make this work, however, is debatable; and much depends on how you define it....


6

You can find the amount of unusable fuel in the EASA Type Certificate Data Sheet. Here is an example table for the A320-200 from that document: In general, the cockpit displays will always show the amount of usable fuel only. This is mandated e.g. by EASA CS 25.1337: (b) Fuel quantity indicator. There must be means to indicate to the flight-crew members, ...


5

Areas on the airplane with ice protection have it for important reasons: Ice on the wing/empennage disrupts airflow, adding drag and making it more susceptible to stalling. Ice on an engine cowl lip can disrupt flow into the engine, causing stability issues. If it dislodges it can damage the engine. Ice in the pitot/static system prevents the air data ...


4

This is an indirect answer at best, but I think you'll get something good out of it. I would definitely recommend you have look at CuriousMarc's series on YouTube where he and a couple other SMEs restore an original Apollo Guidance Computer to working order. You might think "that's not civil aviation, why?", but the AGC was the first digital fly-by-wire ...


4

Definitions provided by the FAA can be found in AC 120-28D - Criteria for Approval of Category III Weather Minima for Takeoff, Landing, and Rollout. From the document we find for Fail Operational: 4.3.2. Fail Operational Category III Operations. A Fail Operational System is a system which after failure of any single component, is capable of completing ...


3

If it's the flap closing, you should be able to verify that from the APU ECAM page. Based on the time frame you mentioned, most likely it's the simulated overspeed, which is part of the shutdown sequence and is basically the signal that closes the fuel solenoid (which you can also verify from the APU page). APU flap closing comes later. For more on the ...


3

Many accidents have shown over and over that once the handling becomes muscle memory, the cue that having to pull harder means you are losing speed is easily missed anyway, so it's not as important as it seems. So the artificial neutral stability instead decouples the controls: stick for flight path angle, thrust levers or A/T for speed. Nice and easy and ...


2

I don't think the quote you gave is correct. This might be the case for some aircraft (like the Boeing 777 with 3 autopilots), but not in general. A more general definition is: Autoland systems are normally designated Fail Operational or Fail Passive. A Fail Operational system must have at least two autopilots engaged for the approach. The failure ...


1

Wings need undisturbed airflow in order to create lift. Even a small covering of ice can lead to a significant loss of lift. Noses do not create lift, all ice accumulation may do is increase the weight of the airplane a small amount, which isn't a big enough concern to warrant the cost and weight of an ice prevention system.


1

Please read carefully ... Extract taken from my FCOM, Info accurate at January 2020: An emergency ram air inlet ventilates the cockpit and cabin to remove smoke, or if both packs fail. The emergency ram air inlet valve is controlled by the RAM AIR pushbutton on the AIR COND panel. This pushbutton opens the ram air valve, provided that ditching is not ...


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