Originally Posted by
737 Driver
If I recall correctly, the "5 second" remark was specifically in reference to a certain set of steps on the runaway stab trim checklist. Apparently there is a "demo" video on YouTube that gives the impression that it takes longer, and someone was under the impression that this length of time was one of the things working against the crew. I was simply pointing out that it could have been done quicker. In another post, however, I also pointed out that the crew could take all the time they needed to get the aircraft back to neutral trim as long as one of the pilots was, yes, FLYING THE AIRCRAFT and managing the trim using the yoke switch.
I recall it a bit differently. It was a longer exchange starting with a comment about the first step in your mantra. I claimed that "turning off the magic" is made more difficult on the MAX, because it contains an additional bit of magic that can't be turned off without losing manual electric trim as well. As a solution I proposed introducing a software update (since a hardware change like rewiring the cutout switches differently would be more costly), which would allow the pilots to disable MCAS and other types automatic electric trim without losing manual electric trim. You replied that the new feature would involve more troubleshooting, and the philosophy is that pilots should not troubleshoot problems, and procedurally they shouldn't fiddle with the cutout switches. I replied that the runway stabilizer memory items already look a bit like troubleshooting, saying "do this, if that doesn't work do that, if that doesn't work finally do that". What I meant was that a bit more troubleshooting in addition to the existing troubleshooting steps wouldn't be the end of the world. For example the "fiddling" part could be added as deferred items. Especially since two sets of pilots experiencing MCAS did just that. They fiddled with the cutout switches after initially disabling stabilizer trim.
Then you replied that those "troubleshooting" steps in the memory items can be done in "
under 5 seconds". I felt that sounded a bit like an exaggeration. First of all the pilot flying would have to hold firmly the control column. This means he would have to rely on the pilot not flying to actually execute rest of the memory items, since his hands are busy. I assumed the pilot not flying will not just do the rest of the items blindly and hastily, without confirming them with the pilot flying first, so I didn't see how that that can be done in under 5 seconds. So I replied with a partial transcript of a Mentour video, demonstrating the execution of the memory items, where the "troubleshooting" part took
43 seconds. Mentour is a captain with over 10000 hours experience on the 737. He is also a line training captain, type rating instructor, and type rating examiner.
I agree that in the demo video they were not executing the memory items as fast as possibile, and in a real emergency it would probably be wise to execute them faster. What I didn't mention was that, including problem identification, it actually took them
83 seconds between the start of the runaway and using the cutout switches, including the time needed to identify the problem. The full transcript and the link to the video by Mentour is in one of my older posts in this thread, here:
Ethiopian airliner down in Africa
It is possible Mentour was exaggerating by making the execution of the memory items too long and too formal. Or you were exaggerating with your "under 5 seconds" claim. Or both. Alternatively there may be some misunderstanding on my part.
After your "don't tell me how to fly the plane" post I took a break from posting yesterday to allow the things to calm down. Even if I don't agree with everything you say, I appreciate your informed contributions to this forum, and that you are trying not to let the discussion go "into the weeds". As for me, I'm just a passenger that is interested in this MAX saga. I only post when somebody makes claims that are clearly wrong without anybody contradicting him (for example the "the pilots allowed the plane to reach 500 knots without doing anything" post, or the "pilots in the previous Lion Air flight immediately used the cutout switches"), or when I feel that the facts or opinions I post are valuable to the discussion.
Unfortunately I'm not very good at interacting with people, and I'm sorry if my posts may seem disrespectful, I am just giving my honest opinion.
Now to different topic, the AoA disagree light. First, we have the revelation that Boeing didn't know that it doesn't work if the AoA display optional feature was not installed. OK, that's understandable, it's a bug that has slipped through testing. It happens. Then they say they analyzed the impact and they concluded it doesn't affect the safety. OK, fair enough, a lot of pilots have expressed similar opinions.
But then there is decision to not inform either the FAA or the airlines about the problem. Hiding this information IS actually a safety issue, in my opinion. OK, let's say 95% of the pilots don't care about the AoA disagree light. But the remaining 5% might be confused in a AoA disagree situation, assuming the disagree light works correctly and there is nothing wrong with the angle of attack vanes. Instead those pilots may suspect issues with the pitot probes the static ports or some other issues when they get a false stick shaker.
And even the part about the disagree indicator itself not being a safety feature is debatable. For example, after the previous Lion Air flight, if this indicator worked properly its activation might have been recorded in the flight and maintenance log, and the maintenance crew might have tested replaced the faulty vane, and we wouldn't have the Lion Air accident.
But then, the cherry on top is Boeing not even knowing how their planes work. First claiming that when the related option is installed AoA disagree light can activate on the ground, then realizing after a few months that actually you need to be at least 400 feet above ground level for it to activate. I don't even know what to say about that. They didn't give the contractor that implemented that piece of software exact specifications about how it should work? If they did, how is it possible they didn't know? Did somebody later assume it works just like on the NG, without checking the documentation before telling the airlines? I assume it works on the ground for NGs, during the takeoff roll, otherwise I can't find any reasonable explanation for this surreal display of incompetence on Boeings part.