7 ms·

But presumably the pilots of both downed MAXs were pulling back as hard as possible.

by tus88 7y ago

bookofjoe 7y ago
>Suneja hauled his control column all the way back, giving full up elevator to no avail. The nose dropped farther as the stabilizer prevailed. The crew of an offshore oil platform saw the airplane in a nearly vertical dive before it hit the water.(Lion Air Flight 610) >As the speed shot through 450 knots, the pilots hauled back on their control columns to no effect. Six minutes after takeoff, the airplane hit the ground doing approximately 600 miles an hour. It buried itself into a 30-foot-deep crater in farmland about 32 miles southeast of the airport. Within a week, the Boeing 737 Max was grounded worldwide. (Ethiopian Airlines Flight 302) From: https://www.nytimes.com/2019/09/18/magazine/boeing-737-max-crashes.html https://www.nytimes.com/2019/09/18/magazine/boeing-737-max-c...
kart23 7y ago
So scary. It's like driving a car, trying to slow down, slamming on the brake, but it just keeps accelerating. Cant imagine everyone's feelings on those flights.
- blattimwind 7y ago
  The good thing with cars is that the time to avert a crash is generally very low (<1 second - <10 seconds), so while you're bending the supports of your seat pushing down on the brake pedal in panic, that state is not going to last very long.
  - toss1 7y ago
    Well also with a car, you can jut put it in Neutral and let the engine rev and throw a piston while you coast off to the side
    - PhantomGremlin 7y ago
      I don't know if it works that way any more. Nowadays with CVT or with PDK it seems to me that you're merely making a "suggestion" to put the transmission into Neutral. If the transmission software is borked, you're screwed? But I'm not sure, maybe there is some fail safe override that occurs when you physically move the transmission control stalk into the neutral position? I'd say that you could always turn the engine off. But Toyota made a mockery of that. Q: Who knew that you needed to press and hold the OFF button for a full five seconds before the car decided to comply? A: Not everyone knew --- people died!
      - toss1 7y ago
        Agree, I'm not happy with the electronics just taking it as a suggestion to go to N or shut off engine while rolling. Sure, it's got risks, but it is a key element of driver control. At least with my Mazda, I couldn't get a manual transmission, but the thing will go to N while rolling (haven't yet tried Off). And yes, even with lots of experience, I'm not sure I'd figure out to hold the OFF button for 5 full seconds in a unintended acceleration scenario -- that's damn deadly!!
      - blattimwind 7y ago
        > Nowadays with CVT or with PDK it seems to me that you're merely making a "suggestion" to put the transmission into Neutral. If the transmission software is borked, you're screwed? Nice thing about a standard transmission is that unless the linkage breaks you can always pull it out of gear, even under load. > I'd say that you could always turn the engine off. You can't necessarily turn a Diesel off [1], and I would not be surprised if modern very-high compression gasoline engines are able to pull the same runaway off. [1] Big Diesel generators have countermeasures for runaway, but cars don't.
    - gonzo 7y ago
      You can turn off the key, too.
- sokoloff 7y ago
  Though no doubt terrifying, the crew of ETH302 failed to reduce thrust; doing so may have allowed them to save the airplane.
  - EdwardDiego 7y ago
    Do you have something I can read on that "may"? I don't disagree that the throttles weren't moved, but the part about it maybe having saved them is new information.
    - sokoloff 7y ago
      I'll give you the short explanation and then an article reference supporting. That might give you other terms to further research. The trim is driven by a jackscrew. That jackscrew is driven by a mechanism in the cockpit (a large double wheel near each flight crew station). At low and moderate airspeeds, the jackscrew turns relatively easily. At high airspeeds and low elevator deflections (meaning "when the aircraft is approximately in trim"), the jackscrew turns relatively easily. At high airspeeds and high elevator deflections, the forces on the tail make the jackscrew difficult to turn due heavy forces. This would be the case where the aircraft is trimmed heavily nose down and the crew is holding large amounts of up elevator to compensate. (You're basically cranking the tail into a different position against the air loads on it.) Slowing the airplane down would almost surely have helped the crew by reducing these loads. If you're going too fast (information the crew had available to them both in cockpit and confirmed by radio after they inquired while fighting), 94% N1 is not where you want the engines set. It's not a popular or comfortable position to look into the actions of the crew and find areas for improvement in light of the fact that they were dealt a very difficult situation that morning. Even with that, it appears that they correctly diagnosed the root of the issue, correctly disabled the electric trim [memory item on the checklist], for some reason left the engines at takeoff power [possibly just overlooked them, though overlooking engine power setting is like overlooking breathing to pilots], and when even knowing it was part of the problem, they correctly re-enabled the electric trim system in order to help them manage the situation, they then failed to command continuous nose up electric trim [which would have cut out MCAS and given them assistance in trimming the aircraft nose up]. The only reason to have the malfunctioning electric trim back on is to command nose up trim. Why turn it on, immediately command nose up, then stop and leave the faulty system engaged? That crew was so close to saving the aircraft that it's frustrating as a pilot and a human. Slight adjustments to the above sequence and they're rightly heroes alongside Captains Sullenberger and Haynes. https://www.reuters.com/article/us-ethiopia-airplane-procedures-explaine/explainer-ethiopia-crash-raises-questions-over-handling-of-faults-on-boeing-737-max-idUSKCN1RG2PP https://www.reuters.com/article/us-ethiopia-airplane-procedu...
chawco 7y ago
Even more than that, you pick up speed due to the nose down configuration. This means the forces on the control surfaces are so great that you can no longer manually trim via the trim wheels. This was, apparently, a well known handling characteristic of the 737, with original versions describing a "roller coaster" maneuver where you dive briefly to relieve the forces on the control surfaces and incrementally trim. Unfortunately, because of how MCAS was set up, it was inactive while flaps were set, but kicked in immediately upon flaps up, meaning that they essentially had no altitude to work with. See: https://www.youtube.com/watch?v=aoNOVlxJmow&t=1008s https://www.youtube.com/watch?v=aoNOVlxJmow&t=1008s for a flight sim recreation of this situation on an NG. Everything here seems to be that exceptional pilots can (and did) save the situation, but that it's not straightforward even with training.
- rainbowzootsuit 7y ago
  The "roller coaster" manoeuver: It's like reeling in a marlin, but everyone's life is dependent upon your success.

But presumably the pilots of both downed MAXs were pulling back as hard as possible.

by tus88 7y ago

But presumably the pilots of both downed MAXs were pulling back as hard as possible.

>Suneja hauled his control column all the way back, giving full up elevator to no avail. The nose dropped farther as the stabilizer prevailed. The crew of an offshore oil platform saw the airplane in a nearly vertical dive before it hit the water.(Lion Air Flight 610) >As the speed shot through 450 knots, the pilots hauled back on their control columns to no effect. Six minutes after takeoff, the airplane hit the ground doing approximately 600 miles an hour. It buried itself into a 30-foot-deep crater in farmland about 32 miles southeast of the airport. Within a week, the Boeing 737 Max was grounded worldwide. (Ethiopian Airlines Flight 302) From: https://www.nytimes.com/2019/09/18/magazine/boeing-737-max-crashes.html https://www.nytimes.com/2019/09/18/magazine/boeing-737-max-c...

kart23 7y ago

So scary. It's like driving a car, trying to slow down, slamming on the brake, but it just keeps accelerating. Cant imagine everyone's feelings on those flights.

blattimwind 7y ago
The good thing with cars is that the time to avert a crash is generally very low (<1 second - <10 seconds), so while you're bending the supports of your seat pushing down on the brake pedal in panic, that state is not going to last very long.
- toss1 7y ago
  Well also with a car, you can jut put it in Neutral and let the engine rev and throw a piston while you coast off to the side
  - PhantomGremlin 7y ago
    I don't know if it works that way any more. Nowadays with CVT or with PDK it seems to me that you're merely making a "suggestion" to put the transmission into Neutral. If the transmission software is borked, you're screwed? But I'm not sure, maybe there is some fail safe override that occurs when you physically move the transmission control stalk into the neutral position? I'd say that you could always turn the engine off. But Toyota made a mockery of that. Q: Who knew that you needed to press and hold the OFF button for a full five seconds before the car decided to comply? A: Not everyone knew --- people died!
    - toss1 7y ago
      Agree, I'm not happy with the electronics just taking it as a suggestion to go to N or shut off engine while rolling. Sure, it's got risks, but it is a key element of driver control. At least with my Mazda, I couldn't get a manual transmission, but the thing will go to N while rolling (haven't yet tried Off). And yes, even with lots of experience, I'm not sure I'd figure out to hold the OFF button for 5 full seconds in a unintended acceleration scenario -- that's damn deadly!!
    - blattimwind 7y ago
      > Nowadays with CVT or with PDK it seems to me that you're merely making a "suggestion" to put the transmission into Neutral. If the transmission software is borked, you're screwed? Nice thing about a standard transmission is that unless the linkage breaks you can always pull it out of gear, even under load. > I'd say that you could always turn the engine off. You can't necessarily turn a Diesel off [1], and I would not be surprised if modern very-high compression gasoline engines are able to pull the same runaway off. [1] Big Diesel generators have countermeasures for runaway, but cars don't.
  - gonzo 7y ago
    You can turn off the key, too.
sokoloff 7y ago
Though no doubt terrifying, the crew of ETH302 failed to reduce thrust; doing so may have allowed them to save the airplane.
- EdwardDiego 7y ago
  Do you have something I can read on that "may"? I don't disagree that the throttles weren't moved, but the part about it maybe having saved them is new information.
  - sokoloff 7y ago
    I'll give you the short explanation and then an article reference supporting. That might give you other terms to further research. The trim is driven by a jackscrew. That jackscrew is driven by a mechanism in the cockpit (a large double wheel near each flight crew station). At low and moderate airspeeds, the jackscrew turns relatively easily. At high airspeeds and low elevator deflections (meaning "when the aircraft is approximately in trim"), the jackscrew turns relatively easily. At high airspeeds and high elevator deflections, the forces on the tail make the jackscrew difficult to turn due heavy forces. This would be the case where the aircraft is trimmed heavily nose down and the crew is holding large amounts of up elevator to compensate. (You're basically cranking the tail into a different position against the air loads on it.) Slowing the airplane down would almost surely have helped the crew by reducing these loads. If you're going too fast (information the crew had available to them both in cockpit and confirmed by radio after they inquired while fighting), 94% N1 is not where you want the engines set. It's not a popular or comfortable position to look into the actions of the crew and find areas for improvement in light of the fact that they were dealt a very difficult situation that morning. Even with that, it appears that they correctly diagnosed the root of the issue, correctly disabled the electric trim [memory item on the checklist], for some reason left the engines at takeoff power [possibly just overlooked them, though overlooking engine power setting is like overlooking breathing to pilots], and when even knowing it was part of the problem, they correctly re-enabled the electric trim system in order to help them manage the situation, they then failed to command continuous nose up electric trim [which would have cut out MCAS and given them assistance in trimming the aircraft nose up]. The only reason to have the malfunctioning electric trim back on is to command nose up trim. Why turn it on, immediately command nose up, then stop and leave the faulty system engaged? That crew was so close to saving the aircraft that it's frustrating as a pilot and a human. Slight adjustments to the above sequence and they're rightly heroes alongside Captains Sullenberger and Haynes. https://www.reuters.com/article/us-ethiopia-airplane-procedures-explaine/explainer-ethiopia-crash-raises-questions-over-handling-of-faults-on-boeing-737-max-idUSKCN1RG2PP https://www.reuters.com/article/us-ethiopia-airplane-procedu...

chawco 7y ago

Even more than that, you pick up speed due to the nose down configuration. This means the forces on the control surfaces are so great that you can no longer manually trim via the trim wheels. This was, apparently, a well known handling characteristic of the 737, with original versions describing a "roller coaster" maneuver where you dive briefly to relieve the forces on the control surfaces and incrementally trim. Unfortunately, because of how MCAS was set up, it was inactive while flaps were set, but kicked in immediately upon flaps up, meaning that they essentially had no altitude to work with. See: https://www.youtube.com/watch?v=aoNOVlxJmow&t=1008s https://www.youtube.com/watch?v=aoNOVlxJmow&t=1008s for a flight sim recreation of this situation on an NG. Everything here seems to be that exceptional pilots can (and did) save the situation, but that it's not straightforward even with training.

rainbowzootsuit 7y ago
The "roller coaster" manoeuver: It's like reeling in a marlin, but everyone's life is dependent upon your success.