4 ms·
In theory, nothing here is obscure. Trim is a control that airplanes have that cars don't. It's a very basic control, it's right there on the control column.
by cjbprime 8y ago
In theory, nothing here is obscure. Trim is a control that airplanes have that cars don't. It's a very basic control, it's right there on the control column. A mechanical or computer failure could cause the plane to mistrim itself, so one of the most basic emergency responses that every airliner pilot knows is how to disable the auto-trim and fix it manually. MCAS is a new way for mistrim to happen, but there were already many others before.
It sounds like the main issue is that Boeing didn't predict that MCAS would mistrim at such low altitude that you don't have time to disable the trim motor and perform the recovery before the ground intervenes.
- miketery 8y ago> nothing here is obscure Boeing chose to have the indicators that show the trim is on as a separate add on, not as a default feature (i.e. an indicator showing the trim is enabled). This is beyond unsafe, and unethical by all measures. For a car it would be like having cruise control turn on automatically and accelerating (without telling you), and worse yet, when you brake to try to control your speed, it doesn't disable or do anything (pulling on the steering column did nothing). To disable you need to do something totally different (which is unnatural for a human). I hope this error is costly to Boeing, and that the FAA learns from this experience. This should have never been certified.
- cjbprime 8y ago> Boeing chose to have the indicators that show the trim is on as a separate add on, not as a default feature (i.e. an indicator showing the trim is enabled). This is nonsense. The optional light was just an AoA disagree sensor. It doesn't provide any information about trim.