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Old 1st May 2019, 21:11
  #4720 (permalink)  
dingy737
 
Join Date: Aug 2008
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Originally Posted by slacktide
Yes, it was. The "automatics" failed by providing undesired and uncommanded control inputs, but this was not the initiating failure that the pilots failed to react to. MCAS did not become a factor until a full minute and fifteen seconds into the flight. The inital failure that was presented to the pilots was stickshaker on takeoff with UAS. Rather than manually flying the aircraft using pitch and power as required by the memory items on the UAS NNC checklist, the accident pilots tried to re-engage the autopilot multiple times, and relied on the autothrottle to manage power, which put them above VMo. This directly contradicts the UAS NNC checklist which has the pilots disengage the autopilot, autothrottle, and flight director as memory items for the first three steps, and further goes on to state "Do not use the the autopilot, autothrottle, or flight directors." Look at the timeline:

5:37:34 ATC clears flight for takeoff
5:38:44 (just after liftoff) AOA disagree, airspeed disagree, altitude disagree, and stickshaker are indicated in FDR
5:38:46 Master Caution light illuminates.
5:38:58 Pilots attempt to engage autopilot
5:39:00 Pilots attempt to engage autopilot
5:39:22 Pilots successfully engage autopilot
5:39:45 Flap retraction begins
5:39:55 Autopilot disengages
5:40:00 MCAS begins MCAS-ing

So, it was a minute and fifteen seconds between the initial indication of a failure, and the undesired, uncommanded trim input. During that time, the pilots did not execute a single step of the UAS NNC checklist that they should have been following from memory. But they sure spent a lot of time heads-down button-pushing that autopilot. It's clear that they were not comfortable manually flying the aircraft as the checklist requires. To be noted, until 5:40:00, the airplane would have been behaving exactly as an NG would during the same type of AOA vane failure, and the procedure to follow during UAS is identical.


1. Excerpt from Boeing FCOM Philosophy and Assumptions; “• the full use of all automated features (LNAV, VNAV, autoland, autopilot, and autothrottle). This does not preclude the possibility of manual flight for pilot proficiency where allowed” in other words become masters of automation.

2. “startle Factor” + prolonged confusion = Panic

3. Panic = return to comfort Zone.

4. Hence at 50’ LNAV selected and 400’ VNAV selected and Autopilot attempted, “HAL” will fix it.

5. What would that comfort zone be? Automation of course. That’s what the industry teaches.

6. Manual flight with a flight director ON does little to solve the issue, it must be flight director and autothrottle off to achieve the familiarity and thus comfort zone. Do we want pilots flying commercial jets as if in a Cessna 152? Catch 22.

Question

1. At 100’ what was the difference in IAS Left vs Right? Is it clear which is erroneous? Could your Trim sheet/ Load sheet be wrong?

2. At what timeline should they have identified UAS and not an approach to stall?

3. If UAS identified should they have powered back to 80% N1 and Pitch 10”?

4. How much does the stick shaker noise, vibration, low altitude and low time FO affect you, and when was the last time you trained for this?

5. Hundreds of hours and discussion on this thread and no consensus, but this flight lasted 6 minutes and was doomed by 3 minutes.

With what we know now, all on this thread could survive the same scenario, how about before?

Pilots are so trained to follow the memory items; it doesn’t allow them to fly on instinct in panic mode. Panic Mode starts with wings level, pitch and power and let the brain settle.


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