Originally Posted by
yanrair
I like you don't like semantics, like "was the STAB TRIM" actually "continuous".
Y
Is that really how you imagine troubleshooting on the flight deck of an airliner to work?
"Hey, the airplane is trimming repeatedly in a direction I don't like, but we cannot use this procedure here because it says the trim needs to be 'continuous'. Drat!"
The problem is not semantics, although that is an important concept and I don't like people using the word to imply "it is just splitting hairs". It is not. It is about what we mean by words.
The problem is identifying the issue in the first place. Identifying that the trim movements are in fact pathological. Automatic trim inputs are normal and expected on the 737, mostly from the STS, and in situations where high angle of attack values are delivered (valid or not), a lot else is going on that requires your immediate attention, such as stick shaker and IAS disagree. Trimming occasionally to remove stick forces is second nature to any pilot, from light GA singles to large airliners (Airbus FBW autotrim notwithstanding), for a while you wouldn't even think about it. And then there is the problem of perhaps throwing the baby out with the bathwater, i. e. the evaluation of what functions are lost when electric trim is completely disabled. Remember that there is no way to disable MCAS only.
The
symptoms are significantly different from runaway trim, which is a trained procedure precisely because the time in which the pilots need to react may be very short for a real runaway, to a large part because manual trim inputs may not stop it. But manual trim inputs
do stop MCAS trim inputs. So it is substantially different from a runaway and is much harder to diagnose, and this has nothing whatsoever to do with "just semantics".
Bernd