Originally Posted by
silverstrata
Clearly MCAS is not a runnaway trim condition, otherwise we would be reaching for the cut-out switches every time the speed-trim operated. I think some people here do not realise that the trimmer doing its own thing is operations normal.
And the auro-trim systems are always mis-trimming the aircraft (the trim inputs by the speed-trim system are always wrong, and you always have to re-trim manually). So at what point does ‘operations normal’ become ‘operations abnormal’? At what point do you assume that the trimmer has gone awry..??
Silver
I am going to disagree with you. You are technically correct, but the captain on the Lion aircraft that crashed manually corrected for MCAS input 21 or so times. 21 times there was a 10 second trim input by MCAS, followed by 21 times a 10 second ( I assume pilot electric trim and MCAS trim at the same rate but I can be wrong about that) electric trim input by the captain. I know there were 5 second breaks without trim, but I would have to think this is not even close to normal. Of course they had all sorts of other bells and whistles going off, but the captain was able to keep the aircraft in trim, so he must have known there was a trim issue too. I am on brand A, but I have a few hundred hours in the 737 cockpit as
JS/non working crew. I have been paying attention, and have never seen STS doing anything close to a 10 second trim run, and it will generally trim ANU after take-off, as the pilot is trying to accelerate, and STS wants to keep the speed constant, whereas MCAS was continuously AND.