02:11:37 (Robert) Commandes à gauche!Yeah, Bonin fucked up the most, but Robert was not on top of the situation either.
Left seat taking control!
At last, the more senior of the pilots (and the one who seems to have a somewhat better grasp of the situation) now takes control of the airplane. Unfortunately, he, too, seems unaware of the fact that the plane is now stalled, and pulls back on the stick as well. Although the plane's nose is pitched up, it is descending at a 40-degree angle. The stall warning continues to sound. At any rate, Bonin soon after takes back the controls.
Just then an alarm sounds for 2.2 seconds, indicating that the autopilot is disconnecting. The cause is the fact that the plane's pitot tubes, externally mounted sensors that determine air speed, have iced over, so the human pilots will now have to fly the plane by hand.It seems like it would be a good idea to try to figure out alternate ways for the plane to measure wind speed, maybe with some kind of radar system or backup anemometers that are heated forcefully enough to avoid icing?
It's quite possible that Bonin had never flown an airplane in alternate law, or understood its lack of restrictions. According to Camilleri, not one of US Airway's 17 Airbus 330s has ever been in alternate law. Therefore, Bonin may have assumed that the stall warning was spurious because he didn't realize that the plane could remove its own restrictions against stalling and, indeed, had done so.Interesting. With something like this maybe there should be a reminder that the controls had gone unreliable.
When the Pilot Flying (PF) makes an input on the sidestick, an order (an electrical signal) is sent to the fly-by-wire computer. If the Pilot Not Flying (PNF) also acts on the stick, then both signals/orders are added.Note that despite the "dual input" warning on AF447, neither pilot exercised control by pressing the sidestick priority button. Which further underscores the "nobody really took command" CRM argument.
Therefore, as on any other aircraft type, PF and PNF must not act on their sidesticks at the same time.
If the PNF (or Instructor) needs to take over, the PNF must press the sidestick takeover pushbutton, and announce: "I have control".
Despite the gap in seniority and experience, the captain leaves Bonin in charge of the controls.It reminded me too much of this:
In spite of the fact that the weather was very poor (wet with low visibility, causing the cancellation of many flights that day at La Guardia), Captain Martin permitted First Officer Constantine Kleissas to make the takeoff on a short, wet runway, even though he would be conducting his first non-supervised line takeoff in a 737, and had not conducted any takeoffs during the last 39 days.Only two people died that time. RIP aunt Ayles and cousin Betsy.
02:11:37 (Robert) Commandes à gauche!Neither pilot understood the situation or what to do to correct it.
Left seat taking control!
At last, the more senior of the pilots (and the one who seems to have a somewhat better grasp of the situation) now takes control of the airplane. Unfortunately, he, too, seems unaware of the fact that the plane is now stalled, and pulls back on the stick as well. Although the plane's nose is pitched up, it is descending at a 40-degree angle. The stall warning continues to sound. At any rate, Bonin soon after takes back the controls.
Pilots who fly sidesticks think they're the greatest thing since sliced bread, and pilots who fly yokes say there's no other way to go. In fact, both systems are excellent methods of connecting a pilot to an airplane.The notion that the cause of this crash was that Robert did not realize that Bonin had the stick back is simply unsupported by the transcript.
In any case, I put the disaster squarely on the shoulder of the people who designed the flight control system. Letting the pilots operate the controls in a conflicting manner like this where they have no idea what the other is doing is a disaster waiting to happen. I'm only surprised it took this long.The plane is designed with the expectation the pilots should know how to use it. It's not like a car where we don't really expect users to have much understanding or awareness. They should have both realized the correct thing to do was nose down rather then continuing to pull back in hope of gaining speed.
How about an alarm that sounds when the two pilots' stick input is divergent to a significant degree for, say, three sustained seconds. The computer would then say, "Divergent stick inputs." This would tell the two pilots that they are dealing with the situation differently (and so might have two different ideas as to what is happening).As it's been established, they had that. A "Dual Input" warning.
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posted by nathancaswell at 2:39 PM on December 7, 2011 [18 favorites]