7 ms·

The reason this preliminary report is so damning is that it's evident that the pilots on flight 302 knew this - they realised what was happening, took the neces

by makomk 8y ago

The reason this preliminary report is so damning is that it's evident that the pilots on flight 302 knew this - they realised what was happening, took the necessary steps to disable MCAS, and still couldn't stop the plane from crashing and killing everyone on board.

treis 8y ago
The took the necessary steps and it was working until they went off script. Whether or not their hand was force because the script stopped working remains to be seen. IMHO, there's little to do except to wait for the full report to come out. The speculation about the crash was wildly wrong and the preliminary report coming out didn't really stop that.
- msbarnett 8y ago
  > The took the necessary steps and it was working until they went off script. Whether or not their hand was force because the script stopped working remains to be seen The script required them to manually crank in the stabilizer, which wasn't possible. The script was manifestly not "working". That doesn't "remain to be seen" -- it's in the transcript of the cockpit
  - treis 8y ago
    Yes, people are speculating this and like the previous speculation they're probably wrong.
    - msbarnett 8y ago
      > At 05:40:35, the First-Officer called out “stab trim cut-out” two times. Captain agreed and First- Officer confirmed stab trim cut-out. > At 05:41:46, the Captain asked the First-Officer if the trim is functional. The First-Officer has replied that the trim was not working and asked if he could try it manually. The Captain told him to try. At 05:41:54, the First-Officer replied that it is not working. I guess the First-Officer must have been speculating...
      - kayfox 8y ago
        Its not clear if the pilots meant trimming it manually with the switches or with the trim wheel.
      - treis 8y ago
        Pilots are often wrong about what their aircraft is doing. In fact, that's a big reason why they crash. So yes, the First Officer said that but that is not conclusive proof that they couldn't manually trim. He may have misinterpreted the question and tried the electric trim again. Or maybe he tried turning the wheel and didn't do it right. Or maybe he needed to try again. Or maybe he needed the pilots help. Or maybe the manual trim system was broken. There's any number of explanations for that statement. Until someone sits down and calculates the torque needed to manually trim it's all just speculation.
        cjbprime 8y ago
        Bear in mind that they're at low altitude and the pilot is busy supplying maximum pull on the yoke, and therefore likely unavailable to help crank a stiff trim wheel.
        treis 8y ago
        >Bear in mind that they're at low altitude They weren't >the pilot is busy supplying maximum pull on the yoke, Probably not true either >and therefore likely unavailable to help crank a stiff trim wheel Runaway trim should be a recoverable situation. If that's impossible then that means there is a distinct and major issue beyond MCAS.
        ddalex 8y ago
        I wouldn't feed the troll, but I don't want your misinformation to spread. > They weren't They just took off, max height of the airplane was 1000 feet above the ground. That's a definely low altitude. > Runaway trim should be a recoverable situation. The trim pointed the nose down. The aerodynamic forces were so high on the elevator that the trim wheels could not be moved by a single person. This was confirmed in 737 simulator.
- ambicapter 8y ago
  Why are you speaking authoritatively about what the pilot's did and in the same breath admonishing people for not waiting for the "full report"?
  - treis 8y ago
    Because the preliminary report contains data showing that electric trim was re-engaged.
    - msbarnett 8y ago
      Why are you dismissing the data the report contains indicating that the flight crew was unable to trim manually, that the column forces were incredibly high, and that the captain repeatedly indicated he could not maintain elevator trim without the co-pilot's aid, then? Your responses have been incredibly selective about which parts of the report you take as gospel and which you handwave away as "speculation". From where I'm sitting it appears you've started out by picking a contrarian conclusion you like ("the plane was safe once STAB CUTOUT was set cutout, and the crew could have maintained altitude indefinitely at that point, but fatally fucked up by re-engaging electronic trim to try to trim the stabilizer"), and to maintain that a priori conclusion you've consistently ignored the data and parts of the transcript that indicate that was very likely impossible.
      - treis 8y ago
        >Why are you dismissing the data the report contains indicating that the flight crew was unable to trim manually, that the column forces were incredibly high Where is that data in the report?
        msbarnett 8y ago
        > At 05:40:44, the Captain called out three times “Pull-up” and the First-Officer acknowledged. > At 05:41:30, the Captain requested the First-Officer to pitch up with him and the First-Officer acknowledged. > At 05:43:04, the Captain asked the First Officer to pitch up together and said that pitch is not enough. Take a look at the chart of control column position deflections. They're jolting around like crazy at +10 to +15 aft starting immediately at the first big MCAS trim event through to the end of the recording. That's because the stabilizer mis-trim is exerting considerable force on the elevator. The captain wasn't calling for aid on the column for shits and giggles.
ams6110 8y ago
Read the narrative in the report. Why do you suppose that after they got the same initial signs of trouble that the Lion Air flight had (stick shaker on left side, disagreement in airspeed values, etc. immediately after takeoff) that the captain tried to engage autopilot and instructed the first officer to retract flaps and inform controllers they were proceeding to climb to FL 320 (32,000 ft). Why not instead turn back and land and hand the aircraft over to maintenance? From the report: At 05:38:44, shortly after liftoff, the left and right recorded AOA values deviated. Left AOA decreased to 11.1° then increased to 35.7° while value of right AOA indicated 14.94°. Then after, the left AOA value reached 74.5° in ¾ seconds while the right AOA reached a maximum value of 15.3°. At this time, the left stick shaker activated and remained active until near the end of the recording. Also, the airspeed, altitude and flight director pitch bar values from the left side noted deviating from the corresponding right side values. The left side values were lower than the right side values until near the end of the recording. ... At 05:39:06, the Captain advised the First-Officer to contact radar and First Officer reported SHALA 2A departure crossing 8400 ft and climbing FL 320. ... 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. 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. Bear in mind stick shaker and divergent instrument readings all this time. Why not just return and land, leave the flaps configuration alone (which would have inhibited MCAS), especially since this is exactly how the Lion Air flight started. I know this is easy to critique from the comfort of my chair, and the pilots are not here to defend themselves, but some things in this narrative just don't make sense.
- cjbprime 8y ago
  Of course they would have tried to land after getting the plane under control. They didn't have airspeed or altitude under control, and were following the checklists they were supposed to be following. IAS Unstable tells them to leave thrust high and flaps alone to avoid a wing stall.
- cmurf 8y ago
  Stick shaker activation isn't a rare event. Quite a lot of stick shaker events happen in low risk situations. And quite a lot of them are false positives. http://www.atsb.gov.au/publications/2012/ar-2012-172.aspx http://www.atsb.gov.au/publications/2012/ar-2012-172.aspx Experience sounds like a good thing on the face of it, but it also adds noise where all of these indications sound familiar enough, and yet nothing in particular stands out and tells you to leave flaps alone. That suggestion isn't even in the emergency airworthiness directive. And still at the time of this event there's no simulator that can be configured for MCAS upset so that pilots can experience it in various phases of flight. Also, the priority in a flight control problem is to fly the plane, get it stabilized, understand the problem, and turning back to the airport is inconsistent with that. Fly runway heading is the proper thing to do, it's less complicated. A turn increases angle of attack, increases drag, it makes a high angle of attack situation worse, and if you're trying to climb it reduces your rate of climb.

by makomk 8y ago

treis 8y ago

The took the necessary steps and it was working until they went off script. Whether or not their hand was force because the script stopped working remains to be seen. IMHO, there's little to do except to wait for the full report to come out. The speculation about the crash was wildly wrong and the preliminary report coming out didn't really stop that.

msbarnett 8y ago
> The took the necessary steps and it was working until they went off script. Whether or not their hand was force because the script stopped working remains to be seen The script required them to manually crank in the stabilizer, which wasn't possible. The script was manifestly not "working". That doesn't "remain to be seen" -- it's in the transcript of the cockpit
- treis 8y ago
  Yes, people are speculating this and like the previous speculation they're probably wrong.
  - msbarnett 8y ago
    > At 05:40:35, the First-Officer called out “stab trim cut-out” two times. Captain agreed and First- Officer confirmed stab trim cut-out. > At 05:41:46, the Captain asked the First-Officer if the trim is functional. The First-Officer has replied that the trim was not working and asked if he could try it manually. The Captain told him to try. At 05:41:54, the First-Officer replied that it is not working. I guess the First-Officer must have been speculating...
    - kayfox 8y ago
      Its not clear if the pilots meant trimming it manually with the switches or with the trim wheel.
    - treis 8y ago
      Pilots are often wrong about what their aircraft is doing. In fact, that's a big reason why they crash. So yes, the First Officer said that but that is not conclusive proof that they couldn't manually trim. He may have misinterpreted the question and tried the electric trim again. Or maybe he tried turning the wheel and didn't do it right. Or maybe he needed to try again. Or maybe he needed the pilots help. Or maybe the manual trim system was broken. There's any number of explanations for that statement. Until someone sits down and calculates the torque needed to manually trim it's all just speculation.
      - cjbprime 8y ago
        Bear in mind that they're at low altitude and the pilot is busy supplying maximum pull on the yoke, and therefore likely unavailable to help crank a stiff trim wheel.
        treis 8y ago
        >Bear in mind that they're at low altitude They weren't >the pilot is busy supplying maximum pull on the yoke, Probably not true either >and therefore likely unavailable to help crank a stiff trim wheel Runaway trim should be a recoverable situation. If that's impossible then that means there is a distinct and major issue beyond MCAS.
        ddalex 8y ago
        I wouldn't feed the troll, but I don't want your misinformation to spread. > They weren't They just took off, max height of the airplane was 1000 feet above the ground. That's a definely low altitude. > Runaway trim should be a recoverable situation. The trim pointed the nose down. The aerodynamic forces were so high on the elevator that the trim wheels could not be moved by a single person. This was confirmed in 737 simulator.
ambicapter 8y ago
Why are you speaking authoritatively about what the pilot's did and in the same breath admonishing people for not waiting for the "full report"?
- treis 8y ago
  Because the preliminary report contains data showing that electric trim was re-engaged.
  - msbarnett 8y ago
    Why are you dismissing the data the report contains indicating that the flight crew was unable to trim manually, that the column forces were incredibly high, and that the captain repeatedly indicated he could not maintain elevator trim without the co-pilot's aid, then? Your responses have been incredibly selective about which parts of the report you take as gospel and which you handwave away as "speculation". From where I'm sitting it appears you've started out by picking a contrarian conclusion you like ("the plane was safe once STAB CUTOUT was set cutout, and the crew could have maintained altitude indefinitely at that point, but fatally fucked up by re-engaging electronic trim to try to trim the stabilizer"), and to maintain that a priori conclusion you've consistently ignored the data and parts of the transcript that indicate that was very likely impossible.
    - treis 8y ago
      >Why are you dismissing the data the report contains indicating that the flight crew was unable to trim manually, that the column forces were incredibly high Where is that data in the report?
      - msbarnett 8y ago
        > At 05:40:44, the Captain called out three times “Pull-up” and the First-Officer acknowledged. > At 05:41:30, the Captain requested the First-Officer to pitch up with him and the First-Officer acknowledged. > At 05:43:04, the Captain asked the First Officer to pitch up together and said that pitch is not enough. Take a look at the chart of control column position deflections. They're jolting around like crazy at +10 to +15 aft starting immediately at the first big MCAS trim event through to the end of the recording. That's because the stabilizer mis-trim is exerting considerable force on the elevator. The captain wasn't calling for aid on the column for shits and giggles.

ams6110 8y ago

Read the narrative in the report. Why do you suppose that after they got the same initial signs of trouble that the Lion Air flight had (stick shaker on left side, disagreement in airspeed values, etc. immediately after takeoff) that the captain tried to engage autopilot and instructed the first officer to retract flaps and inform controllers they were proceeding to climb to FL 320 (32,000 ft). Why not instead turn back and land and hand the aircraft over to maintenance? From the report: At 05:38:44, shortly after liftoff, the left and right recorded AOA values deviated. Left AOA decreased to 11.1° then increased to 35.7° while value of right AOA indicated 14.94°. Then after, the left AOA value reached 74.5° in ¾ seconds while the right AOA reached a maximum value of 15.3°. At this time, the left stick shaker activated and remained active until near the end of the recording. Also, the airspeed, altitude and flight director pitch bar values from the left side noted deviating from the corresponding right side values. The left side values were lower than the right side values until near the end of the recording. ... At 05:39:06, the Captain advised the First-Officer to contact radar and First Officer reported SHALA 2A departure crossing 8400 ft and climbing FL 320. ... 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. 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. Bear in mind stick shaker and divergent instrument readings all this time. Why not just return and land, leave the flaps configuration alone (which would have inhibited MCAS), especially since this is exactly how the Lion Air flight started. I know this is easy to critique from the comfort of my chair, and the pilots are not here to defend themselves, but some things in this narrative just don't make sense.

cjbprime 8y ago
Of course they would have tried to land after getting the plane under control. They didn't have airspeed or altitude under control, and were following the checklists they were supposed to be following. IAS Unstable tells them to leave thrust high and flaps alone to avoid a wing stall.
cmurf 8y ago
Stick shaker activation isn't a rare event. Quite a lot of stick shaker events happen in low risk situations. And quite a lot of them are false positives. http://www.atsb.gov.au/publications/2012/ar-2012-172.aspx http://www.atsb.gov.au/publications/2012/ar-2012-172.aspx Experience sounds like a good thing on the face of it, but it also adds noise where all of these indications sound familiar enough, and yet nothing in particular stands out and tells you to leave flaps alone. That suggestion isn't even in the emergency airworthiness directive. And still at the time of this event there's no simulator that can be configured for MCAS upset so that pilots can experience it in various phases of flight. Also, the priority in a flight control problem is to fly the plane, get it stabilized, understand the problem, and turning back to the airport is inconsistent with that. Fly runway heading is the proper thing to do, it's less complicated. A turn increases angle of attack, increases drag, it makes a high angle of attack situation worse, and if you're trying to climb it reduces your rate of climb.