undefined | Better HN

0 pointsinferiorhuman7y ago0 comments

> In theory then, solving the stabilizer problem that caused the crash is as simple as flipping both switches to cutoff, then using the wheel to set the stabilizer back to a sane value.

https://www.youtube.com/watch?v=rxPa9A-k2xY

The issue for the Lion Air pilots was time. At 5,000 ft you don't have time to adjust the trim before you hit the ground. While I think that the stabilizer trim can be adjusted more quickly than the video shows you'd still be looking at somewhere around the order of 30 seconds end to end.

0 comments

VBprogrammer7y ago

The elevators still have some authority, you don't have to wind it from end to end to regain control. Also, the full range of mechanical motion is only available via the trim wheel, the electronic trim doesn't drive it to either extreme (although it can move it back to the centre from an extreme).

inferiorhumanOP7y ago

> The elevators still have some authority, you don't have to wind it from end to end to regain control.

If you're at a low altitude and managing other problems will you have enough time to even recognize the problem and then wind the cranks and recover before you hit the ground?

> Also the full range of mechanical motion is only available via the trim wheel, the electronic trim doesn't drive it to either extreme (although it can move it back to the centre from an extreme).

Can MCAS drive the trim full down? What I've read suggests that if you give it time, it can.

VBprogrammer7y ago

> If you're at a low altitude and managing other problems will you have enough time to even recognize the problem and then wind the cranks and recover before you hit the ground?

My suspicion is that it would probably have required a well drilled crew to have handled the problem correctly. But I don't think we're up there with the extraordinary levels of piloting which we've seen demonstrated previously e.g. Flight 1549 (the miracle on the Hudson).

> Can MCAS drive the trim full down? What I've read suggests that if you give it time, it can.

I'd be surprised if it can drive it outside the normal range of electronic motion. There aren't really enough details out there for me to be sure though.

inferiorhumanOP7y ago

Yeah. I suspect that if MCAS played a deciding role in JT 610 the flight would have been survivable if the pilots were made aware of how the plane handles with faulty AoA data.

Although it may simply turn out that the MAX is a much more delicate plane to fly, something along the lines of DC-10 vs MD-11.

> I'd be surprised if it can drive it outside the normal range of electronic motion. There aren't really enough details out there for me to be sure though.

Yep. There are a lot of questions (at least in my mind) including why the Brazilians and Europeans (LOT, TUI) knew about MCAS and the Americans (US + Canada) and Indonesians did not.

1 more reply

j / k navigate · click thread line to collapse

0 comments

VBprogrammer7y ago

inferiorhumanOP7y ago

> The elevators still have some authority, you don't have to wind it from end to end to regain control.

If you're at a low altitude and managing other problems will you have enough time to even recognize the problem and then wind the cranks and recover before you hit the ground?

> Also the full range of mechanical motion is only available via the trim wheel, the electronic trim doesn't drive it to either extreme (although it can move it back to the centre from an extreme).

Can MCAS drive the trim full down? What I've read suggests that if you give it time, it can.

VBprogrammer7y ago

> If you're at a low altitude and managing other problems will you have enough time to even recognize the problem and then wind the cranks and recover before you hit the ground?

> Can MCAS drive the trim full down? What I've read suggests that if you give it time, it can.

I'd be surprised if it can drive it outside the normal range of electronic motion. There aren't really enough details out there for me to be sure though.

inferiorhumanOP7y ago

Yeah. I suspect that if MCAS played a deciding role in JT 610 the flight would have been survivable if the pilots were made aware of how the plane handles with faulty AoA data.

Although it may simply turn out that the MAX is a much more delicate plane to fly, something along the lines of DC-10 vs MD-11.

> I'd be surprised if it can drive it outside the normal range of electronic motion. There aren't really enough details out there for me to be sure though.

Yep. There are a lot of questions (at least in my mind) including why the Brazilians and Europeans (LOT, TUI) knew about MCAS and the Americans (US + Canada) and Indonesians did not.

1 more reply

j / k navigate · click thread line to collapse