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Ethiopia Reveals Initial Boeing 737 MAX Crash Findings

The Ethiopian Ministry of Transport’s Aircraft Accident Investigation Bureau released its Interim Investigation Report regarding the 2019 Ethiopian Airlines 737 MAX crash. The report goes over the crash and the events leading up to it in excruciating detail. ( 기타...

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Think for a minute that instead of a possible bird strike disabling the left AOA vane allowing it to give false information, a flock of birds damages both left and right AOA vanes and they both erroneously send info back to the aircraft that is in a stall scenario? However the aircraft attitude, speed, rate of climb are all normal but both stick shakers are firing, the aircraft is trying to trim itself downwards because of known/unknown MCAS...thrust is at climb power! The crew finally turn off the trim cut-out switches while manually trimming but do not reduce power. The aircraft still about 7000’ above ground and now in 100’ fpm descent and almost under control.....the crew decides to turn the cut-out switches back on (probably because they are uncomfortable hand flying) to get the autopilot back and the aircraft dives into the ground at over 5000’ fpm. Bad design for sure, poorly trained crew probably, sign of the times by pushing both aircraft and pilots out the door without adequate testing......definitely. Just an opinion.
Where do you get the idea of the plane being 7000' above the ground? The Addis airport is at nearly 7000' elevation. This explains the continued take-off thrust, the rapid acceleration and the very short duration of the flight.
The aircraft reached 6,200’agl which translates into approx. 13,200’ asl using your stats. The crew had set 14.000 into their altitude alerter.
Flightradar 24 tracker shows highest altitude was about 8500' AMSL. Field elevation is actually 7625'. You can do the math.
875 feet above ground level.
NTSB Report - abbreviated

At 5:42:12, the crew requested a vector to return to the airport.

At 5:42:15, the F/O requested “Radar Ethiopian three zero two request vector to return to home » Following ATC instruction to turn to 260°, a new target heading of 262 ° was set.The aircraft heading at that time was 102 degrees.

At 5:42:47, the captain said « Ok, what was it? Master Caution? The F/O says« Master caution? » The captain asked the F/O to verify. The F/O answered “Master Caution Anti Ice”. The captain said “Left Alpha Vane”. The F/O acknowledged“Left Alpha Vane” the FDR data at this time is consistent with the crew pressing the MASTER CAUTION recall button to review the existing faults.

During this phase, the crew was applying an average force of 94 lbs for a long time.

From 5 h 41 min 25 s, bank angle progressively increased to the right and heading increased towards the new selected heading.

At the end of the phase:

- The airplane was at an altitude of 6,200 ft above the airfield elevation (computed from the RH pressure altitude). LH altitude values were 1,250 ft lower.
- Computed airspeed was around 367 kt (RH value), LH erroneous value was 344 kt.
- The pitch angle of the airplane was lower than 1°
- The vertical speed was around + 125 ft/min and decreasing
- The bank angle was around 21° right, with a slight trend to increase.

Phase 5: Stab trim cut out switches back in normal position until the end of the flight (from 5h 43 min 11 s until 5h 43 min 44 s)

At 5:43:11, the crew tried to engage the A/P. A/P warning sounded for 3 s.

At the time of the A/P engagement attempt, 2 short-time manual electrical trim up inputs were recorded , from which it can be concluded that the stabilizer cutout switches had been restored to the normal position6; at this time, the stabilizer position was 2.3 units.

At 05:43:21, approximately five seconds after the last manual electric trim up input, automatic nose-down trim triggered for about 5 s. The stabilizer moved from 2.3 to 1 unit. 3 seconds after the automatic nose-down trim activation, the vertical speed decreased and became negative.

One second before the end of the automatic trim nose-down activation, the average force applied by the crew decreased from 100 lbs to 78 lbs in 3.5 seconds.

In these 3.5 seconds, the pitch angle dropped from 0.5° nose up to -7.8° nose down and the descent rate increased from -100 ft/min to more than -5,000 ft/min.Following the last automatic nose-downtrim activation and despite recorded force of up to 180 lbs, the pitch continued decreasing. The descent rate and the airspeed continued increasing.

At 05:43:36 the EGPWS sounded: “Terrain, Terrain, Pull Up, Pull up”
The recordings stoped 23 seconds after the activation of the 4th automatic nose down trim.

At the end of the recording:

- Computed airspeed values reached 500 kt
- Pitch values were greater than 40° nose down
- Vertical speed values were greater than 33,000 ft/min.

Both recorders stopped recording at around 05 h 43 min 44 s.
Not really possible unless measured over some dramatically lower terrain, which doesn't appear. Not even within the rate of climb capabilities of the 737. Also, pressure altitude is not measured AGL but AMSL.
You're trying to argue a blog post from 2019 has more reliable data than a NTSB report?

The series of events with the accident doesn't even make sense if the airplane was at 875' AGL.
Allan, read this again slowly:
The airplane was at an altitude of 6,200 ft above the airfield elevation (computed from the RH pressure altitude). LH altitude values were 1,250 ft lower.
What I said was that Flightradar24 flight tracking last reported altitude as about 8500' AMSL. That was at 05:41. I do not believe the plane climbed another 6000' in the remaining two minutes of flight with MCAS pointing the nose at the ground. So yes I think the NTSB report has an error. And, to repeat myself, barometric altimeters do not measure the vertical distance from terrain.
I've heard of both AOA sensors being waterlogged before takeoff and freezing in flight, but if two birds got close enough to seriously damage either AOA sensor, it'd be all but guaranteed that other things on the airplane would be damaged as well.
I was just using a flock of birds as an example that if both AOA’s were damaged and giving bad information and the aircraft was flying normally except that MCAS activated, the QRH or memory items for runaway trim are the same....cut out switches to off. It wouldn’t matter if Boeing wired one or two AOA sensors into MCAS as the crew actions are the same. However, they Boeing should never have been allowed to deliver an aircraft with just one warning sensor wired and an optional light?
Yes, there have been many accidents in the past where systems relying on single sensors for information were a factor. But that's my only criticism of Boeing in regards to the 737 MAX.
It strikes me as a pretty significant criticism. This was done to circumvent training and type certification requirements. It is at a bare minimum a moral outrage, with both Boeing and Southwest Airlines to blame.
Lack of training between aircraft variants was a factor in the crash of British Midland Flight 92 in 1989.
Greg S 1
A badly mistrimmed stabilizer can be difficult or impossible to move manually. I've noticed in your other MAX comments that it's clear you never actually read the reports. In this interim report the CVR transcripts suggest that the pilots were unable to get the stabilizer to budge manually. They almost certainly reconnected the trim motor so they could use the electric trim switches, and that was almost certainly the correct decision given the situation at that moment. In fact, that really should have been part of the guidance for MCAS deviations. First fight MCAS by using the electric trim switches to restore proper trim, then quickly engage the cutout switches to prevent MCAS from moving the stabilizer again. There's always a few seconds between MCAS activations during which you can slay the MCAS beast by using the trim cutoff switches.

There is no doubt in my mind that poor pilot decisions played a major role here as well as in the Lion Air case, including inexperienced and inadequately trained pilots. The "captain" of this flight was all of 29 years old, the first officer was 25.
Manually trimming the stabilizer is possible but not when you're at Vmo... I feel it's safe to say if the AC wasn't traveling as fast as it was they would have been able to land after manually trimming.

MCAS at any point could be stopped by the use of electronic trim, once the pilot was done trimming the AC MCAS would wait 5 seconds before trimming the stabilizer if the high AOA condition still existed. The common thread between the Lion Air and this accident is that it seemed that the captains understood that they needed to continually add ANU trim, once the controls were handed off to the FO in both cases no additional ANU trim was added and the FOs tried to overcome the trimming stabilizer via elevator control.
That’s what I would say.
Both 737's had 1 think in common that none in the US have, and that is they only had 1 AOA Vane. In the US, per FAA they ware required to have 2. That is one big difference why ours are safer than theirs.... I still do not believe a Bird Strike caused the damage however. ALL Airline Class world wide should be required to have 2 AOA Vanes. If that had been in place, neither crash most likely would have never happened.
This is utterly wrong in pretty much every respect. All MAX planes had two AOA sensors. All had the MCAS hooked up to one at a time. FAA requirements are not limited to planes "in the US", whatever that is thought to mean by this ill-informed person.
MCAS is unfortunately wired to just one of the two AOA vanes. You really have to feel for these crews on the Max because I’ll bet they had no idea what was happening. Most training is concentrated on engine failures, IRS failures and general flying procedures and a lot of electrical issues are auto switched these days. I wonder if there should be an FAA mandated minimum equipped aircraft standard to prevent some airlines and leasing companies from ordering bare bones/stripped down planes to maximize profit on investment?
sparkie624 -2
I know this report says it has 2, but all the others says it only had 1.
Greg S 7
The 737 has two (2) AoA vanes, one on each side. MCAS only reads from a one of the vanes, but two are available.


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