2 ms·
“…The documentation provided to the pilots did not therefore allow them to reasonably envisage that, in the event of antagonistic control inputs exceeding the b
by K0balt 3y ago
“…The documentation provided to the pilots did not therefore allow them to reasonably envisage that, in the event of antagonistic control inputs exceeding the breakout mechanism's activation threshold, the controls would be desynchronized and the control surface would react according to the mean control positions. The behaviour of the aeroplane during this phase of simultaneous control inputs could not be anticipated.”
It is unconscionable that the training for this aircraft does not include a thorough examination of competence in interpreting multiple control inputs/control jamming.
The fact that under these conditions the aircraft defaults to responding to -neither- control input, but rather the mean of the two, without any master caution or obvious alarm condition seems like a dubious engineering decision at best, and certainly should merit significant training to recognize the conditions under which the -aircraft would decide not to respond fully to ANY control input- .
Of course, cockpit discipline is paramount, and this near-accident was a direct result of CRM failure, but by design the control system makes this forseeable eventuality much more insidiously dangerous and disorienting to pilots. At the very least, significant training on the specific possibility is merited, and an alarm condition for this specifically out of parameter situation should exist.
If I didn’t know better, I would suspect that Boeing was intentionally engineering their flight control automation systems to exploit foreseeable pilot errors and exacerbate them, and then maliciously forgoing trading requirements on those features.
- masklinn 3y agoTBF the behaviour of averaging dual inputs is exactly what Airbus does as well.
- K0balt 3y agoHopefully that decision is based then on sound engineering and aviation principles. I can certainly see that as a “better than nothing “ approach, and I can imagine some failure scenarios where it might even be the -best- solution… but it would seem that that operating mode would at least merit enough training so that pilots would recognize the operating mode, as well as some kind of obvious indication that the airplane was electing to algorithmicly synthesize the control outputs. Wouldn’t it be better to simply hard-lock the controls together, with a release switch for each control to allow either pilot to unlock their controller from the other in case of a stuck control system or an uncooperative pilot? That would seem to capture the benefits of de synchronizable controls while avoiding the empirically problematic downside.