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I guess the correlation here is the stalling problem often happens during this height range. Both 737 were in the ascending process, while the 767 is during no

by xmly 8y ago

I guess the correlation here is the stalling problem often happens during this height range. Both 737 were in the ascending process, while the 767 is during normal flying. For me, the 767 hit with some kind of strange turbulence then the engines went to max and caused a typical stall crash. You could google about the stall crash, such as : https://www.dw.com/en/why-do-airplanes-stall-and-why-is-it-so-dangerous/a-47869837 https://www.dw.com/en/why-do-airplanes-stall-and-why-is-it-s... For both 737 max, their MCAS system thought they had a stall potential and triggered on nose dive while the airplanes were actually in the perfectly normal situation. For 767, they do not have this autonomous system and the stall warning was not even triggered. So it was a purely manual operation. If they have a perfectly functioned MCAS like the 737 max has, they may have survived. So a working MCAS could save plane from crash like 767 had. Just the MCAS on 737 max was not working correctly and MAY potentially have caused the tragedy.

drawkbox 8y ago
> Both 737 were in the ascending process, while the 767 is during normal flying. It might not have anything to do with ascent/descent but the range / altitude and how systems react at that altitude. Maybe the systems are designed to be more reactive at this height because there is less chance to recover than if you are cruising at 30k feet. What is most interesting to me is how the Amazon cargo plane 767 crash made almost zero news and has quickly been replaced in the news with the 737 Max 8/9 issues. Though all situations are very similar, straight nose dives that were sudden at the 6000-8500 feet range. There has to be something to that. 767 crashes and emergencies are EXTREMELY rare [1]. Most are related to human intervention such as terrorism, pilot error, fuel error and only a very small amount are mechanical errors. Of the 12 problems, only 5 were mechanical error. [1] https://en.wikipedia.org/wiki/Category:Accidents_and_incidents_involving_the_Boeing_767 https://en.wikipedia.org/wiki/Category:Accidents_and_inciden...
- xmly 8y ago
  That is probably because 767 is a plane with quite a long history without any major upgrade. And it is cargo, so no passengers. The first 737 Max crashed in Indonesia, it did not have quite media coverage as well. The second one got much more attention because that is quite rare that two brand new flights crashed in such a short period. Everyone suspected it is caused by design or system flaws.
  - drawkbox 8y ago
    > That is probably because 767 is a plane with quite a long history without any major upgrade. And it is cargo, so no passengers. 767 is a passenger and cargo plane. I assume you mean the Amazon 767 was a cargo plane [1], in which case yes it got less attention as only the pilots/cargo crew were on board. However, a 767 crashing in the US seems like it would have gotten more focus. Other 767s are passenger planes including two infamous ones American Airlines Flight 11 (Boeing 767-223ER) and United Airlines Flight 175 (Boeing 767-200) that were the two planes that crashed into the World Trade Center tower 1 & 2 on 9/11 [2][3]. For the most part these planes don't crash and a straight nose dive is a freak occurrence. Most of the other issues that weren't crashes with 767 were landing gear, short fuel related and terrorism. It is very strange and eerie that this 767 from Amazon crashed almost similarly to the 737 Max 8/9 in Indonesia and Ethiopia recently, with such a long history of nothing like this. [1] https://en.wikipedia.org/wiki/Atlas_Air_Flight_3591 https://en.wikipedia.org/wiki/Atlas_Air_Flight_3591 [2] https://en.wikipedia.org/wiki/American_Airlines_Flight_11 https://en.wikipedia.org/wiki/American_Airlines_Flight_11 [3] https://en.wikipedia.org/wiki/United_Airlines_Flight_175 https://en.wikipedia.org/wiki/United_Airlines_Flight_175
- AnimalMuppet 8y ago
  > There has to be something to that. Well, no, there doesn't have to be something to that. Random data often exhibits clusters. However, it is unwise to assume that there isn't something to that. It just also is unwise to assume that there is. Keep an open mind and investigate.
  - drawkbox 8y ago
    The only way a plane would need to pitch down -49 degrees is if the plane thinks it is, or is, 40-50 degrees or more pitched up. The only thing I can think of why that would happen is a software error. Possibly the common occurrence of these planes where the nose is pitching up 4 degrees repeatedly to an almost turbulent state, then possibly the software on the plane thinks it is additively pitched up if there were 10-15 incorrect nose adjustments up of 4 degrees. Could be a race condition, lock or some other issue where it only happens at that altitude because it has to adjust faster to prevent crashes and the lower you are the harder it is to recover. My guess is the software acts more decisively at lower altitudes under 9-10k because that is closer to the ground and where some areas of the US have peaks in elevation to, so the aircraft must act quicker because it is less recoverable at that stage. Another possibility is since it was a cargo plane there was shifting during the turbulent state but the plane was stabilized and moved up 100 feet before the -49 degree nose down state so that seems unlikely. Pilot error seems unlikely as well as the pilots were skilled. Mechanical failure seems rare as 767s just do not have nose down errors like this and almost no mechanical causes of emergencies or crashes. There is always the possibility of sabotage as well, there are reasons groups might want to take down an Amazon owned plane. Though most likely this is a software error or something exploited.
cmurf 8y ago
I'm not certain that particular 767 has a stick shaker but I'd be surprised if it didn't. My concern with any cargo airplane crash is weight and balance, was center of gravity in the normal envelope, and did anything shift during turbulence? That shouldn't happen, but if it does, it can really adversely affect stall avoidance and recovery. From the look of the grainy surveillance video of that crash, it could be stall crash, it does vaguely look like they might have been recovering but flat out had insufficient altitude. Also with respect to MCAS, it's not a factor when the autopilot is enabled, as the autopilot shouldn't permit approaching the edges of the normal envelope with such a high angle of attack that the MCAS routine would apply. I haven't read any report about whether the autopilot was enabled or not; let alone the exact sequence of modes enabled and disabled. So the autopilot itself can't be excluded as a suspect until there's evidence it was a non-factor.
- gonesilent 8y ago
  The Amazon leased 767 that crashed was a full on cargo version. Cargo is stored in large containers. And the aircraft filled with them. Things shifting in those tend to only shift inside the container. Unless Amazon was shipping lead bricks I don't think any cargo escaped the containers.

by xmly 8y ago

drawkbox 8y ago

> Both 737 were in the ascending process, while the 767 is during normal flying. It might not have anything to do with ascent/descent but the range / altitude and how systems react at that altitude. Maybe the systems are designed to be more reactive at this height because there is less chance to recover than if you are cruising at 30k feet. What is most interesting to me is how the Amazon cargo plane 767 crash made almost zero news and has quickly been replaced in the news with the 737 Max 8/9 issues. Though all situations are very similar, straight nose dives that were sudden at the 6000-8500 feet range. There has to be something to that. 767 crashes and emergencies are EXTREMELY rare [1]. Most are related to human intervention such as terrorism, pilot error, fuel error and only a very small amount are mechanical errors. Of the 12 problems, only 5 were mechanical error. [1] https://en.wikipedia.org/wiki/Category:Accidents_and_incidents_involving_the_Boeing_767 https://en.wikipedia.org/wiki/Category:Accidents_and_inciden...

xmly 8y ago
That is probably because 767 is a plane with quite a long history without any major upgrade. And it is cargo, so no passengers. The first 737 Max crashed in Indonesia, it did not have quite media coverage as well. The second one got much more attention because that is quite rare that two brand new flights crashed in such a short period. Everyone suspected it is caused by design or system flaws.
- drawkbox 8y ago
  > That is probably because 767 is a plane with quite a long history without any major upgrade. And it is cargo, so no passengers. 767 is a passenger and cargo plane. I assume you mean the Amazon 767 was a cargo plane [1], in which case yes it got less attention as only the pilots/cargo crew were on board. However, a 767 crashing in the US seems like it would have gotten more focus. Other 767s are passenger planes including two infamous ones American Airlines Flight 11 (Boeing 767-223ER) and United Airlines Flight 175 (Boeing 767-200) that were the two planes that crashed into the World Trade Center tower 1 & 2 on 9/11 [2][3]. For the most part these planes don't crash and a straight nose dive is a freak occurrence. Most of the other issues that weren't crashes with 767 were landing gear, short fuel related and terrorism. It is very strange and eerie that this 767 from Amazon crashed almost similarly to the 737 Max 8/9 in Indonesia and Ethiopia recently, with such a long history of nothing like this. [1] https://en.wikipedia.org/wiki/Atlas_Air_Flight_3591 https://en.wikipedia.org/wiki/Atlas_Air_Flight_3591 [2] https://en.wikipedia.org/wiki/American_Airlines_Flight_11 https://en.wikipedia.org/wiki/American_Airlines_Flight_11 [3] https://en.wikipedia.org/wiki/United_Airlines_Flight_175 https://en.wikipedia.org/wiki/United_Airlines_Flight_175
AnimalMuppet 8y ago
> There has to be something to that. Well, no, there doesn't have to be something to that. Random data often exhibits clusters. However, it is unwise to assume that there isn't something to that. It just also is unwise to assume that there is. Keep an open mind and investigate.
- drawkbox 8y ago
  The only way a plane would need to pitch down -49 degrees is if the plane thinks it is, or is, 40-50 degrees or more pitched up. The only thing I can think of why that would happen is a software error. Possibly the common occurrence of these planes where the nose is pitching up 4 degrees repeatedly to an almost turbulent state, then possibly the software on the plane thinks it is additively pitched up if there were 10-15 incorrect nose adjustments up of 4 degrees. Could be a race condition, lock or some other issue where it only happens at that altitude because it has to adjust faster to prevent crashes and the lower you are the harder it is to recover. My guess is the software acts more decisively at lower altitudes under 9-10k because that is closer to the ground and where some areas of the US have peaks in elevation to, so the aircraft must act quicker because it is less recoverable at that stage. Another possibility is since it was a cargo plane there was shifting during the turbulent state but the plane was stabilized and moved up 100 feet before the -49 degree nose down state so that seems unlikely. Pilot error seems unlikely as well as the pilots were skilled. Mechanical failure seems rare as 767s just do not have nose down errors like this and almost no mechanical causes of emergencies or crashes. There is always the possibility of sabotage as well, there are reasons groups might want to take down an Amazon owned plane. Though most likely this is a software error or something exploited.

cmurf 8y ago

I'm not certain that particular 767 has a stick shaker but I'd be surprised if it didn't. My concern with any cargo airplane crash is weight and balance, was center of gravity in the normal envelope, and did anything shift during turbulence? That shouldn't happen, but if it does, it can really adversely affect stall avoidance and recovery. From the look of the grainy surveillance video of that crash, it could be stall crash, it does vaguely look like they might have been recovering but flat out had insufficient altitude. Also with respect to MCAS, it's not a factor when the autopilot is enabled, as the autopilot shouldn't permit approaching the edges of the normal envelope with such a high angle of attack that the MCAS routine would apply. I haven't read any report about whether the autopilot was enabled or not; let alone the exact sequence of modes enabled and disabled. So the autopilot itself can't be excluded as a suspect until there's evidence it was a non-factor.

gonesilent 8y ago
The Amazon leased 767 that crashed was a full on cargo version. Cargo is stored in large containers. And the aircraft filled with them. Things shifting in those tend to only shift inside the container. Unless Amazon was shipping lead bricks I don't think any cargo escaped the containers.