Lion Air 737 Max Accident
11-23-2018, 02:02 PM
#81
On Reserve
Joined APC: Mar 2014
Posts: 15
Some excerpts from Indonesian NTSC's exposition to the parliament...Here they presented some relevant data they'd extracted from the FDR on the plane's last flight and on its penultimate one.
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source:
- http://avherald.com/files/lionair_b3..._knkt_data.pdf
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Page 7
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Page 8
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Page 9
source:
- http://avherald.com/files/lionair_b3..._knkt_data.pdf
11-23-2018, 06:49 PM
#82
Gets Weekends Off
Joined APC: Jul 2007
Position: 767 Captain
Posts: 3,988
If you can actually read those graphs on your screen and know what they’re telling us (plus define penultimate 
)..... maybe you could just give us the readers digest version if there’s some kind of relevant info to help explain events leading to the crash.
)..... maybe you could just give us the readers digest version if there’s some kind of relevant info to help explain events leading to the crash.
11-23-2018, 08:34 PM
#83
On Reserve
Joined APC: Mar 2014
Posts: 15
Originally Posted by Adlerdriver
If you can actually read those graphs on your screen and know what they’re telling us (plus define penultimate )..... maybe you could just give us the readers digest version if there’s some kind of relevant info to help explain events leading to the crash.
)..... maybe you could just give us the readers digest version if there’s some kind of relevant info to help explain events leading to the crash.
had the MCAS [color: purple] being shut off. The left stick shaker was ON the whole time. The CAPT & FO AOA sensors disagreed by about 20 Deg. They managed to stay at around FL260-FL280 for the entire flight before landing safely at CGK. For the "ultimate" flight
, the situation was almost similar. The CAPT & FO AOA also had the 20 Deg discrepancy. The stick shaker was on immediately after the take off. However, MCAS [color: purple] went into action immediately after FLAP 0, then it stopped when the plane had gone to FLAP 5 [??] , but MCAS went ballistic again when the plane was back at FLAP 0. PF countered MCAS by manual trim up throughout. The plane managed to stay at FL50 give and take but with the speed of 300+knts[??]. Stabilizer ran close to zero. The plane hit the speed in the excess of 400knts before it crashed to the sea.For clearer pictures...
- http://i.piccy.info/i9/f2d217f2acc4f...ta_Page_07.jpg
- http://i.piccy.info/i9/4f9940a8e5e27...ta_Page_09.jpg
11-24-2018, 08:44 PM
#84
On Reserve
Joined APC: Jan 2008
Posts: 18
Here's what it looks like to me:
From takeoff, the Right AoA sensor consistently reported about 20 degrees higher than the Left AoA sensor. The stick shaker went off almost the entire flight, and the MCAS system was applying periodic nose down trim and the pilots were periodically reacting by applying nose up trim. They're able to maintain a fairly stable situation until what looks like the last little bit. For whatever reason, at the end, there are fewer manual nose up trim inputs, and more automated nose down trim inputs, and the stabilizer eventually reaches full nose-down trim. At the end, it appears that right side pilot is pulling back on the yoke hard and there are fewer trim inputs. The stab trim is going to win over the elevator, and at the end it does.
Total supposition: It's possible they switched flying pilots and the right seat pilot focused more on elevator pressure and didn't apply trim as much as the left seat pilot had, which means that the near-stable situation the left-seat pilot had maintained was lost.
From takeoff, the Right AoA sensor consistently reported about 20 degrees higher than the Left AoA sensor. The stick shaker went off almost the entire flight, and the MCAS system was applying periodic nose down trim and the pilots were periodically reacting by applying nose up trim. They're able to maintain a fairly stable situation until what looks like the last little bit. For whatever reason, at the end, there are fewer manual nose up trim inputs, and more automated nose down trim inputs, and the stabilizer eventually reaches full nose-down trim. At the end, it appears that right side pilot is pulling back on the yoke hard and there are fewer trim inputs. The stab trim is going to win over the elevator, and at the end it does.
Total supposition: It's possible they switched flying pilots and the right seat pilot focused more on elevator pressure and didn't apply trim as much as the left seat pilot had, which means that the near-stable situation the left-seat pilot had maintained was lost.
11-25-2018, 05:37 AM
#85
Gets Weekends Off
Joined APC: Feb 2018
Posts: 579
Originally Posted by 314159
Here's what it looks like to me:
From takeoff, the Right AoA sensor consistently reported about 20 degrees higher than the Left AoA sensor. The stick shaker went off almost the entire flight, and the MCAS system was applying periodic nose down trim and the pilots were periodically reacting by applying nose up trim. They're able to maintain a fairly stable situation until what looks like the last little bit. For whatever reason, at the end, there are fewer manual nose up trim inputs, and more automated nose down trim inputs, and the stabilizer eventually reaches full nose-down trim. At the end, it appears that right side pilot is pulling back on the yoke hard and there are fewer trim inputs. The stab trim is going to win over the elevator, and at the end it does.
Total supposition: It's possible they switched flying pilots and the right seat pilot focused more on elevator pressure and didn't apply trim as much as the left seat pilot had, which means that the near-stable situation the left-seat pilot had maintained was lost.
From takeoff, the Right AoA sensor consistently reported about 20 degrees higher than the Left AoA sensor. The stick shaker went off almost the entire flight, and the MCAS system was applying periodic nose down trim and the pilots were periodically reacting by applying nose up trim. They're able to maintain a fairly stable situation until what looks like the last little bit. For whatever reason, at the end, there are fewer manual nose up trim inputs, and more automated nose down trim inputs, and the stabilizer eventually reaches full nose-down trim. At the end, it appears that right side pilot is pulling back on the yoke hard and there are fewer trim inputs. The stab trim is going to win over the elevator, and at the end it does.
Total supposition: It's possible they switched flying pilots and the right seat pilot focused more on elevator pressure and didn't apply trim as much as the left seat pilot had, which means that the near-stable situation the left-seat pilot had maintained was lost.
11-25-2018, 07:06 AM
#86
Gets Weekends Off
Joined APC: Jul 2007
Position: 767 Captain
Posts: 3,988
Is the solution going to be turning off the stab cutout switches?
That's the burning question in my mind. Would that have solved this issue (switches off, don't exceed current airspeed), or is it a deeper problem?
That's the burning question in my mind. Would that have solved this issue (switches off, don't exceed current airspeed), or is it a deeper problem?
11-25-2018, 01:22 PM
#89
In a land of unicorns
Joined APC: Apr 2014
Position: Whale FO
Posts: 6,465
Originally Posted by pangolin
It’s a stab.
25.255, 25.655 and I think 25.161, and AC25-7B (or whatever the current revision was today).
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