Originally Posted by
coaldemon
Have a look at the data released in the preliminary report for ET302 and see if you can work out what they were doing in the 2 minutes before MCAS came in. That would also be the MCAS they were supposed to have been informed about after the release of the bulletin by Boeing. There are a lot of factors to this one and although MCAS is a flawed concept and has to be fixed the aircraft around it is fine and actually very nice to operate.
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OK. here is my take, where possible times are from the text of report, assumed to be more accurate than reading the chart:
Takeoff roll began from runway 07R at a field elevation of 2333.5 m at approximately 05:38,
Everything looks nominal.
At 05:38:44, shortly after liftoff, the left and right recorded AOA values deviated
This was first indication of trouble, stick shaker and UAS indications.
Although the prelim report does not contain details it is possible the crew determined the UAS to be due to AoA; from Boeing flow chart someone posted a while back. Double quoted so my comments stand out better:
If AoA sensor is failed high,stick shaker on failed side will activate on rotation accompanied by IAS/ALT disagree warning flags
If the pitch power and config are consistent with takeoff and the good side ASI agrees with the Standby ASI,then it is a false warning ----------- >If in any doubt execute the UAS NNC
The symptoms match exact;y and there was not a huge difference in airspeed so they likely did not have a doubt. Anyone know what the standby ASI would show?
The pilot with good side data becomes PF
That did not happen as shown by pilot side AP warnings. The 360 total hours FO just might have something to do with that.
Appears they were not planning an immediate landing, although some of the ATC requests might have been from an 'automatic script' they were used to following.
There were a couple of attempts to engage auto pilot. ending in success at:
At 05:39:22 and about 1,000 feet the left autopilot (AP) was engaged (it disengaged about 33 seconds later),
At this point one could say they were
flying the aircraft as they were trained/used to doing. Whether that is a good thing is a different discusion.
At 05:39:42, Level Change mode was engaged. The selected altitude was 32000 ft. Shortly after the mode change, the selected airspeed was set to 238 kt.
More normal procedure, this is probably the last time anyone thought about airspeed, at least until the clackers went off.
At 05:39:45, Captain requested flaps up and First-Officer acknowledged. One second later, flap handle moved from 5 to 0 degrees and flaps retraction began.
Still a surprisingly 'normal day at the office, although they would not be the first crew to ignore stick shaker and complete a flight, and no I am not referring to Lion air but a US crew report in safety database.
At 05:39:55, Autopilot disengaged,
And this is when MCAS kicked in 5 seconds later. So about 75 seconds from first fault to MCAS, with about half of that with a working autopilot leading them to believe things were basically OK, which in a 737NG they would have been. They were possibly even intending to complete flight for 'commercial' reasons.