Originally Posted by
yanrair
Hi guys
A few points being missed here I think so far. Now some of these are of course just opinion but here goes.....
1 the 737 can fly with everything turned off. It’s a mechanical plane. That is it’s great virtue. So to crash one you have to forget that it’s actually a real ordinary plane and you are meant to be in total control! Always.
2 that being so, if STAB moves unexpectedly, turn off STAB SWITCHES as generations of pilots have done ,and fly straight and level. Why not take control of the plane? You can.
3 MACS only works with autopilot out at high AoA slow speed
4 the fact MACS malfunctions or maybe is not we’ll designed which we don’t know yet, is not the cause of the crash. although it would be desirable if it worked in a sensible manner. Eg two AoA inputs, doesn’t repeatedly incrementally trim nose down and a limit on the number of trim wheel turns etc etc as postulated here.
5 this nose down trim goes back to the 707 which had a stick pusher- it’s not really a new idea at all
6 the cause here? Looks to me like we’re forgetting the basics and the accumulated knowledge of 50 years of operating the 737.
as someone said, the MAX is like a cart (or perhaps a 707)with a couple of computers and glass screens, but underneath it’s a very simple uncomplicated plane. Fly it 6/60 and it will fly. 6 deg nose up. 60% power. Like any other plane.
7 the stabilizer trim switches on the yoke-the ones you use all the time, cannot apparently override (apply automatic brake) against MACS. Now- That’s something very different from the previous models and if true an important issue. But not the cause.
Thats my ten pence worth for today
i would fly a Max in a heartbeat. Provided the pilots
A couple of responses to your points:
1. True, but you don't truly get everything turned off until you use the stabilizer cutout switches. Handling qualities are not certifiable in that configuration.
2. Fully agree.
3. MCAS can operate at any Mach number less than 0.84.
4. Fully agree. Hopefully the MCAS update to be fielded soon addresses all that you raise in this point.
5. There is a fundamental difference between a stick pusher and a system that uses stabilizer. The pitch command increment provided by a pusher is gone as soon as you override and move the column where you want it. The increment of stabilizer motion inserted automatically is not removed via the column and takes either returning to low AOA or pilot commanding the trim in the other direction. Running the stabilizer back takes time.
6. Pitch and power per book recommendations - yes!
7. Pilot operated pitch trim switches on the yoke will temporarily override MCAS. If the conditions for MCAS activation persist, it will come back active 5 seconds after the pilot stops trimming. Lion Air pilot demonstrated this for several minutes. The column cutout switches (not available to the pilot, but tripped when the column is far enough out of neutral) do override the legacy STS function, but do not override MCAS when pulling with MCAS commanding airplane nose down stabilizer.
Cheers