Shouldn't there be an override switch to tell the plane to only accept one of the two control inputs, for situations like this where one of the inputs suffers some physical damage or jam? None of the hundreds of cockpit switches does that? What happens if one pilot dumps their entire cup of coffee onto their controls and it malfunctions causing erroneous input? Is it basically game over?
There is. Google "sidestick priority".
A330 flight control laws saved Voyager, inquiry finds
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Re: A330 flight control laws saved Voyager, inquiry finds
#32It's stated as benefit, but is this the reason pilots get bored perhaps?
Re: A330 flight control laws saved Voyager, inquiry finds
#33Earlier quoted context omitted.
There is. Google "sidestick priority".
Thanks! That is reassuring to know. Shouldn't they have used it in this case when they knew an input was jammed? Obviously it worked out when the computer decided to ignore them, but just curious what the correct procedure should have been here.
According to the below, Airbus cockpit sidesticks have a red button on them. Pressing it disengages the autopilot if it's engaged, which is probably the more normal use. Pressing it when the autopilot is already disengaged engages sidestick priority for as long as it's held down. It latches if held continuously for 40 seconds.
http://aviation.stackexchange.com/questions/3455/why-is-the-...
If they were on the ceiling perhaps it could be difficult to hold the button down continuously for 40 seconds.
Re: A330 flight control laws saved Voyager, inquiry finds
#34I do not understand, it took only one input to put it in a dive with auto pilot engaged but two inputs to cancel auto pilot to get it out of the dive?
Now to the story at hand, the captain probably didn't realize his camera was wedged between the seat's armrest and the control stick as he moved the seat forward. I can only guess that he assumed the strange attitude was the result of a computer malfunction because he considered turning off the computers that provide many of the protections I mentioned. Good thing he didn't. Now the first officer gets into the cockpit and probably tosses a wtf glance at the captain but upon getting one right back he decides to use his own stick. The sticks in the bus aren't mechanically connected but, just like with mechanically connected sticks in antique Boeing aircraft, their force inputs are mathematically summed. Yet unlike mechanically connected sticks, displacement isn't transmitted across the cockpit so the first officer wouldn't be wise to the fact that the captain's stick was full forward. Luckily the bus engineers thought of this. When the first officer pulled his stick back the computer would have noticed both sticks moving and it would have announced "dual input". This isn't a microblog or a gentle woman's voice. It's a pissed off dude trying to talk some sense into you. At that point the captain probably looked at the palms of his hands to make sure they weren't on the stick. He probably showed his palms to the first officer too. At that point they had two heads working on the problem and it wouldn't have taken them too long to find the camera.
Re: A330 flight control laws saved Voyager, inquiry finds
#35not sure it's legit for airbus to be declaring a win for their automation. sounds like the copilot dogpaddled back to the cockpit through freefall and batted at his controls from the ceiling until the computer got confused and resumed level flight. If any safety technology deserves credit here it's seatbelts. From the sound of it, nobody who was belted in was injured.
The automation very possibly saved lives here. The overspeed protection is good because had that not happened, there's a real possibility that significant sections of the airplane would have sheared off, or the airplane could have rapidly drifted further out of control as it accelerated quickly through 365 knots indicated. Big, heavy, thrusting things gain airspeed rapidly when you pitch them down 18 degrees at cruise power, and the margin of recoverability is very minimal. There are arguments that humans are unable to prevent some scenarios in that situation because by the time higher-order thinking on decisions has happened, it's too late. See, for example, the surprisingly lengthy duration of time between the incident and setting for idle, which probably should have been among the first things done in response. Brains are slow when things happen fast, and a symphony of alarms and whoops (undoubtedly in progress) does not help.
A Boeing would not have intervened in the situation at all and would have allowed the aircraft to go overspeed, risking serious airframe damage. If you crash dive an airliner at cruising speed, very, very bad things happen. At cruising altitude safety envelopes are very small. The paragraph talking about direct law is, roughly speaking, what would have happened had this been a Boeing aircraft. (This isn't bad, it's just different philosophies of pilot responsibility. I'm not partisan on the difference like some pilots and am willing to acknowledge the benefits of both approaches; this one is an Airbus advantage.)
Re: A330 flight control laws saved Voyager, inquiry finds
#36I do not understand, it took only one input to put it in a dive with auto pilot engaged but two inputs to cancel auto pilot to get it out of the dive?
I have an A320 type so let me try to guess what happened in the A330. The airbus is... different. You can displace the stick 100% in any direction and it wont bank beyond 67 degrees, pitch up more than 30, or pitch down more than 15. It wont overstress because the stick controls G-forces through a closed feedback loop. It also has high-speed protections where it will automatically apply positive G-force to pitch up i…
Re: A330 flight control laws saved Voyager, inquiry finds
#37not sure it's legit for airbus to be declaring a win for their automation. sounds like the copilot dogpaddled back to the cockpit through freefall and batted at his controls from the ceiling until the computer got confused and resumed level flight. If any safety technology deserves credit here it's seatbelts. From the sound of it, nobody who was belted in was injured.
The computer worked to prevent the aircraft from entering an overspeed condition by pitching up and attempting to recover from the dive even before that dual stick input was an issue. It was intervening 13 seconds into the incident, as the aircraft threatened to exceed safety tolerances. The dual stick input created another issue after that intervention began. The automation very possibly saved lives here. The oversp…
OTOH it's probably a lot harder to "jam" a camera into the center stick of a Boeing than it is into the side-stick of a Bus.
Re: A330 flight control laws saved Voyager, inquiry finds
#38Can anyone familiar with these aircraft opine on why the pilot decided to select TOGA in order to complete recovery? They were at perhaps 28,500 feet at the time. Seems like a a panic reaction.
Re: A330 flight control laws saved Voyager, inquiry finds
#39I do not understand, it took only one input to put it in a dive with auto pilot engaged but two inputs to cancel auto pilot to get it out of the dive?
I have an A320 type so let me try to guess what happened in the A330. The airbus is... different. You can displace the stick 100% in any direction and it wont bank beyond 67 degrees, pitch up more than 30, or pitch down more than 15. It wont overstress because the stick controls G-forces through a closed feedback loop. It also has high-speed protections where it will automatically apply positive G-force to pitch up i…
What does "microblog" mean in this context? I assume it doesn't mean that the A330 isn't posting about its engine thrust on Twitter. (Yet.)
Re: A330 flight control laws saved Voyager, inquiry finds
#40From the article: They then set the thrust levers to idle and raised the aircraft’s nose, before selecting take-off and go-around power and regaining straight and level flight at 31,000ft. Can anyone familiar with these aircraft opine on why the pilot decided to select TOGA in order to complete recovery? They were at perhaps 28,500 feet at the time. Seems like a a panic reaction.
Most aircraft have a slowly stepped climb and descent managed through ATC that gives them plenty of horizontal miles to change their altitude, so they can more gradually adjust in normal flight without having to use max power.
These pilots fell 4,400 feet, I'm sure they wanted to quickly recover to avoid any further problems with other flights in the area.