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As far as I'm aware, it would glide as well as any other 737 if both engines were cut. It merely had a slightly lower maximum nose-up because of the increased e

by jquery 4y ago

As far as I'm aware, it would glide as well as any other 737 if both engines were cut. It merely had a slightly lower maximum nose-up because of the increased engine thrust or something like that.

mc32 4y ago
I'm not in aeronautics obviously and I overstated the case, but my understanding is that the MAX series have different flight characteristics (behaves differently) due to bigger engines which also were moved forward both of which resulted in altering the aerodynamics and flight characteristics --making it different to non MAX 737s... so far, so good. They fly different and you have to treat them differently. But in order to make the pre MAX 737 pilots pre-crosstrained for the new MAXes they installed MCAS systems that made the controls feel like they would respond in a pre MAX 737. In other words computerized compensation. But due to the new flight characteristics you could not exactly fly it like a ore MAX 737 and so if you did bad things could happen if you were not being attentive.
- coredog64 4y ago
  This isn’t correct. There’s one portion of the flight regime where the new engines result in different characteristics. To counter that, the MAX has an automated stick pusher. What’s the alleged fix? Pull the breaker on the overhead panel. There’s a similar failure mode in pre-MAX 737s called “runaway trim”. The giant trim wheels on the center pedestal spin in a loud and attention-getting fashion. The fix? Pull the breaker on the overhead panel.
  - inferiorhuman 4y ago
    > To counter that, the MAX has an automated stick pusher. The MAX does not have a stick pusher. MCAS works on the position (trim) of the stabilizer. The elevator feel system (which the NGs have as well) works by creating additional resistance at the yoke (which is hydraulically assisted). Neither are stick pushers. > There’s a similar failure mode in pre-MAX 737s called “runaway trim”. That's a thing that can happen on any plane with a similar horizontal stabilizer setup. I'm sure even a plane with a flying stabilizer (e.g. L-1011) has similar failure modes. > The giant trim wheels on the center pedestal spin in a loud and attention-getting fashion. The "giant" trim wheels were reduced in size on the NG (and MAX?) reducing their leverage. > The fix? Pull the breaker on the overhead panel. There are two switches (whose function was subtly changed with the MAX) that control the trim motors and they're located behind/below the thrust levers.
- ncmncm 4y ago
  Wrong again. The design goal for the software was to make it fly like other 737s. The software did not actually do that, but did "something" that inspectors allowed was just enough different from without to certify. And, in case of equipment failure, or various other circumstances, the software failed completely, because it was just really badly designed. If you knew about the system, you could turn it off in case of trouble, and then the plane would fly fine, just not enough like a real 737 that you could completely ignore the difference. Then they made it hard to know that the system was there. People who knew how to turn it off could prevent disaster.
  - neor 4y ago
    Correct, switch it off and the plane can fly fine. Thing is though the pilots of the second MAX crash took all the right steps. Just too slow. There was like 10 seconds to turn off mcas, after that a crash was inevitable.
chippiewill 4y ago
> It merely had a slightly lower maximum nose-up because of the increased engine thrust or something like that. It wasn't the engine thrust. There were a bunch of subtle design changes because newer, fuel efficient engines are much larger than the style of engine when the 737 was first designed. Unlike the competing A320, the 737 didn't have the necessary clearance under the wing to fit the new engines. They had to make a bunch of tweaks like moving the engine higher up, further forward, tweak the wings etc. to make it fit with the necessary ground clearance. These subtle differences added up so they added MCAS to make it handle closer to the original design.
- Ekaros 4y ago
  My take on it has been that it might have been fine as it was if it was considered a new plane. Just not software patched modified-737 that it really wasn't. If the pilots were certified with the new characteristic and there wasn't system over riding them, it would have been fine. But instead they wanted to handle like something it wasn't and then made buggy fix for it to do so.
rocqua 4y ago
There was a specific part of the flight envelope where a higher angle of attack would lead to less pressure on the stick. This was a result of the engines being further forward, and thus at high angles of attack having more 'leverage' trying to pitch up the plane. This had two problems. Firstly, this flight characteristic (more AoA gives less stick pressure) is considered risky, because it can trick pilots into thinking the AoA is decreasing. Secondly, and apparently more importantly to Boeing and American Airlines, this meant that pilots certified to fly the old 737 would need to go through new training. This new training was required because of a significant change in flight characteristics and would be very expensive to airlines. So Boeing created MCAS, and tried their best to hide the change so no one would question whether new training might be required. If I recall correctly lion air (the airline of the second MAX crash) had actually asked Boeing if they should do some new simulator training for the 737 max in an e-mail and had been ridiculed for even asking that.

by jquery 4y ago

As far as I'm aware, it would glide as well as any other 737 if both engines were cut. It merely had a slightly lower maximum nose-up because of the increased engine thrust or something like that.

mc32 4y ago

I'm not in aeronautics obviously and I overstated the case, but my understanding is that the MAX series have different flight characteristics (behaves differently) due to bigger engines which also were moved forward both of which resulted in altering the aerodynamics and flight characteristics --making it different to non MAX 737s... so far, so good. They fly different and you have to treat them differently. But in order to make the pre MAX 737 pilots pre-crosstrained for the new MAXes they installed MCAS systems that made the controls feel like they would respond in a pre MAX 737. In other words computerized compensation. But due to the new flight characteristics you could not exactly fly it like a ore MAX 737 and so if you did bad things could happen if you were not being attentive.

coredog64 4y ago
This isn’t correct. There’s one portion of the flight regime where the new engines result in different characteristics. To counter that, the MAX has an automated stick pusher. What’s the alleged fix? Pull the breaker on the overhead panel. There’s a similar failure mode in pre-MAX 737s called “runaway trim”. The giant trim wheels on the center pedestal spin in a loud and attention-getting fashion. The fix? Pull the breaker on the overhead panel.
- inferiorhuman 4y ago
  > To counter that, the MAX has an automated stick pusher. The MAX does not have a stick pusher. MCAS works on the position (trim) of the stabilizer. The elevator feel system (which the NGs have as well) works by creating additional resistance at the yoke (which is hydraulically assisted). Neither are stick pushers. > There’s a similar failure mode in pre-MAX 737s called “runaway trim”. That's a thing that can happen on any plane with a similar horizontal stabilizer setup. I'm sure even a plane with a flying stabilizer (e.g. L-1011) has similar failure modes. > The giant trim wheels on the center pedestal spin in a loud and attention-getting fashion. The "giant" trim wheels were reduced in size on the NG (and MAX?) reducing their leverage. > The fix? Pull the breaker on the overhead panel. There are two switches (whose function was subtly changed with the MAX) that control the trim motors and they're located behind/below the thrust levers.
ncmncm 4y ago
Wrong again. The design goal for the software was to make it fly like other 737s. The software did not actually do that, but did "something" that inspectors allowed was just enough different from without to certify. And, in case of equipment failure, or various other circumstances, the software failed completely, because it was just really badly designed. If you knew about the system, you could turn it off in case of trouble, and then the plane would fly fine, just not enough like a real 737 that you could completely ignore the difference. Then they made it hard to know that the system was there. People who knew how to turn it off could prevent disaster.
- neor 4y ago
  Correct, switch it off and the plane can fly fine. Thing is though the pilots of the second MAX crash took all the right steps. Just too slow. There was like 10 seconds to turn off mcas, after that a crash was inevitable.

chippiewill 4y ago

> It merely had a slightly lower maximum nose-up because of the increased engine thrust or something like that. It wasn't the engine thrust. There were a bunch of subtle design changes because newer, fuel efficient engines are much larger than the style of engine when the 737 was first designed. Unlike the competing A320, the 737 didn't have the necessary clearance under the wing to fit the new engines. They had to make a bunch of tweaks like moving the engine higher up, further forward, tweak the wings etc. to make it fit with the necessary ground clearance. These subtle differences added up so they added MCAS to make it handle closer to the original design.

Ekaros 4y ago
My take on it has been that it might have been fine as it was if it was considered a new plane. Just not software patched modified-737 that it really wasn't. If the pilots were certified with the new characteristic and there wasn't system over riding them, it would have been fine. But instead they wanted to handle like something it wasn't and then made buggy fix for it to do so.

rocqua 4y ago

There was a specific part of the flight envelope where a higher angle of attack would lead to less pressure on the stick. This was a result of the engines being further forward, and thus at high angles of attack having more 'leverage' trying to pitch up the plane. This had two problems. Firstly, this flight characteristic (more AoA gives less stick pressure) is considered risky, because it can trick pilots into thinking the AoA is decreasing. Secondly, and apparently more importantly to Boeing and American Airlines, this meant that pilots certified to fly the old 737 would need to go through new training. This new training was required because of a significant change in flight characteristics and would be very expensive to airlines. So Boeing created MCAS, and tried their best to hide the change so no one would question whether new training might be required. If I recall correctly lion air (the airline of the second MAX crash) had actually asked Boeing if they should do some new simulator training for the 737 max in an e-mail and had been ridiculed for even asking that.