3 ms·

There needs to be a button on the console of every airplane which is "return the airplane to straight and level".

by WalterBright 11mo ago

ryandrake 11mo ago
All modern autopilot systems I've flown have have a LVL (or equivalent) button.
- WalterBright 11mo ago
  When did that happen? I recall the Air France crash over the Atlantic where the pilots got disoriented. And many others, like JFKjr's crash.
  - filleduchaos 11mo ago
    What does the AF 449 crash have to do with the existence of a button to return the aircraft to wings level + zero vertical speed? To answer your question though, LVL has been around for close to two decades now. IIRC there was a Cirrus/Garmin partnership that added it to the latter's G1000/GFC 700 and it's since trickled out to other consumer-grade autopilots.
    - WalterBright 11mo ago
      The AF 449 was in a stall, and the pilots panicked and did exactly the wrong thing. The pilot came out of the lavatory and immediately realized what was wrong, and pushed the stick forward. But it was too late. If the captain could figure it out, so could the computer. I recall another crash, not so long ago, of a commuter plane where the wings iced up a bit and the airplane stalled. The crew kept trying to pull the nose up, all the way to the ground. They could have recovered if they pushed the stick forward - failing basic stall recovery training. There are many others - I've watched every episode of Aviation Disasters. Crew getting spatially disoriented is a common cause of crashes.
      - sseagull 11mo ago
        > a commuter plane where the wings iced up a bit and the airplane stalled. The crew kept trying to pull the nose up, all the way to the ground. There’s probably a lot that match, but sounds like Colgan Air 3407 in 2009 (the last major commercial airline crash in the US before the mid-air collision earlier this year in DC) https://en.wikipedia.org/wiki/Colgan_Air_Flight_3407 https://en.wikipedia.org/wiki/Colgan_Air_Flight_3407
        WalterBright 11mo ago
        Yes, that's the one. Nice work finding it!
      - manarth 11mo ago
        > "If the captain could figure it out, so could the computer." The autopilot had disengaged, most likely because the pitot tubes had iced over. The aircraft system entered ALT2 mode, where bank-angle protection is lost. Protection for angle-of-attack is also lost when 2 or more input references are lost. You might describe these circumstances as the computer saying "I don't know what the heck's going on, you humans figure it out please".
        WalterBright 11mo ago
        As a former engineer who worked on the 757 flight control system, I am not terribly impressed with that design. Having 3 pitot tubes iced over means they read 0 velocity. It is reasonable for the computer to be designed to recognize that if all three pitot tubes read 0, then the pitot tubes are the problem. With the altimeter unwinding, it should be able to recognize a stall. With the turn and bank indicator, and the AOA indicator, it should be able to return to straight and level. Recall that the captain figured it out at a glance and knew exactly what to do.
        manarth 11mo ago
        The FAA report[1] gives a more comprehensive description of events. The pitot tubes had differential icing, and didn't all read 0kts – they reported different velocity against each tube, such as 40kts or 60kts (against an expected baseline of ~ 275kts). The computer correctly recognised the data was invalid and rejected it. It's a common narrative that the captain immediately figured out the issue. The report and transcript of the cockpit recording[2] notes that the captain's interventions showed that he had not identified the stall, nor had the copilots. ~ cockpit recording ~ 0:00 autopilot disconnects 0:01 [copilot right] "I have the controls" 0:11 [copilot right] "We haven't got a good display of speeds" 1:26 captain enters cockpit 1:30 [copilot right] "I don’t have control of the airplane at all" 1:38 [captain] "Er what are you doing?" 3:37 [captain] "No no don't climb" 4:00 [captain] "Watch out you’re pitching up there" 4:02 [copilot right] "Well we need to we are at four thousand feet" 4:23 ~ recording stops ~ [1] https://www.faa.gov/sites/faa.gov/files/AirFrance447_BEA.pdf [2] https://bea.aero/uploads/tx_elyextendttnews/annexe.01.en.pdf
  - CamperBob2 11mo ago
    IIRC, they were dealing with frozen pitot tubes or other sensors that were keeping the air data computing hardware from getting valid input. An automated "Get me out of trouble" button might have had the opposite effect.
    - WalterBright 11mo ago
      As I mentioned elsewhere, the captain figured out what was wrong immediately, but he was too late. BTW, my dad taught instrument flying in the AF. He said it was simple - look at the instruments. Bring the wings level, then the pitch level. Although simple, your body screams at you that it's wrong. He carried with him a steel pipe, so he could beat a student unconscious who panicked and would not let go of the controls. This was against regulation, but he wasn't going to let a student pilot kill him. When JFKjr's crash was on the evening news, he said two words - "spacial disorientation". Months later, that was the official cause.
      - tjohns 11mo ago
        > He carried with him a steel pipe, so he could beat a student unconscious who panicked and would not let go of the controls. Most flight instructors just keep a spare pen in their pocket to jab an uncooperative student in thigh with. (Thankfully almost never used.)
        WalterBright 11mo ago
        His jets were tandem, so he was behind the student. A steel pipe was the only way.
  - deleted 11mo ago
    [deleted]
  - prmoustache 11mo ago
    they were disoriented because a sensor was frozen or something like that and the readings were not correct if I remember correctly, an automatic system would have received the same wrong information.
    - WalterBright 11mo ago
      Since the captain recognized the problem and took corrective action immediately, the avionics could have done so, too.
Mawr 11mo ago
Let go of the controls.
DarmokJalad1701 11mo ago
Most modern avionics stacks have one. Examples: - https://www.garmin.com/en-US/blog/aviation/blue-button-helping-keep-blue-side/ https://www.garmin.com/en-US/blog/aviation/blue-button-helpi... - https://pilotsupport.avidyne.com/kb/article/50-dfc90-wings-level/ https://pilotsupport.avidyne.com/kb/article/50-dfc90-wings-l...

There needs to be a button on the console of every airplane which is "return the airplane to straight and level".

ryandrake 11mo ago

All modern autopilot systems I've flown have have a LVL (or equivalent) button.

WalterBright 11mo ago
When did that happen? I recall the Air France crash over the Atlantic where the pilots got disoriented. And many others, like JFKjr's crash.
- filleduchaos 11mo ago
  What does the AF 449 crash have to do with the existence of a button to return the aircraft to wings level + zero vertical speed? To answer your question though, LVL has been around for close to two decades now. IIRC there was a Cirrus/Garmin partnership that added it to the latter's G1000/GFC 700 and it's since trickled out to other consumer-grade autopilots.
  - WalterBright 11mo ago
    The AF 449 was in a stall, and the pilots panicked and did exactly the wrong thing. The pilot came out of the lavatory and immediately realized what was wrong, and pushed the stick forward. But it was too late. If the captain could figure it out, so could the computer. I recall another crash, not so long ago, of a commuter plane where the wings iced up a bit and the airplane stalled. The crew kept trying to pull the nose up, all the way to the ground. They could have recovered if they pushed the stick forward - failing basic stall recovery training. There are many others - I've watched every episode of Aviation Disasters. Crew getting spatially disoriented is a common cause of crashes.
    - sseagull 11mo ago
      > a commuter plane where the wings iced up a bit and the airplane stalled. The crew kept trying to pull the nose up, all the way to the ground. There’s probably a lot that match, but sounds like Colgan Air 3407 in 2009 (the last major commercial airline crash in the US before the mid-air collision earlier this year in DC) https://en.wikipedia.org/wiki/Colgan_Air_Flight_3407 https://en.wikipedia.org/wiki/Colgan_Air_Flight_3407
      - WalterBright 11mo ago
        Yes, that's the one. Nice work finding it!
    - manarth 11mo ago
      > "If the captain could figure it out, so could the computer." The autopilot had disengaged, most likely because the pitot tubes had iced over. The aircraft system entered ALT2 mode, where bank-angle protection is lost. Protection for angle-of-attack is also lost when 2 or more input references are lost. You might describe these circumstances as the computer saying "I don't know what the heck's going on, you humans figure it out please".
      - WalterBright 11mo ago
        As a former engineer who worked on the 757 flight control system, I am not terribly impressed with that design. Having 3 pitot tubes iced over means they read 0 velocity. It is reasonable for the computer to be designed to recognize that if all three pitot tubes read 0, then the pitot tubes are the problem. With the altimeter unwinding, it should be able to recognize a stall. With the turn and bank indicator, and the AOA indicator, it should be able to return to straight and level. Recall that the captain figured it out at a glance and knew exactly what to do.
        manarth 11mo ago
        The FAA report[1] gives a more comprehensive description of events. The pitot tubes had differential icing, and didn't all read 0kts – they reported different velocity against each tube, such as 40kts or 60kts (against an expected baseline of ~ 275kts). The computer correctly recognised the data was invalid and rejected it. It's a common narrative that the captain immediately figured out the issue. The report and transcript of the cockpit recording[2] notes that the captain's interventions showed that he had not identified the stall, nor had the copilots. ~ cockpit recording ~ 0:00 autopilot disconnects 0:01 [copilot right] "I have the controls" 0:11 [copilot right] "We haven't got a good display of speeds" 1:26 captain enters cockpit 1:30 [copilot right] "I don’t have control of the airplane at all" 1:38 [captain] "Er what are you doing?" 3:37 [captain] "No no don't climb" 4:00 [captain] "Watch out you’re pitching up there" 4:02 [copilot right] "Well we need to we are at four thousand feet" 4:23 ~ recording stops ~ [1] https://www.faa.gov/sites/faa.gov/files/AirFrance447_BEA.pdf [2] https://bea.aero/uploads/tx_elyextendttnews/annexe.01.en.pdf
- CamperBob2 11mo ago
  IIRC, they were dealing with frozen pitot tubes or other sensors that were keeping the air data computing hardware from getting valid input. An automated "Get me out of trouble" button might have had the opposite effect.
  - WalterBright 11mo ago
    As I mentioned elsewhere, the captain figured out what was wrong immediately, but he was too late. BTW, my dad taught instrument flying in the AF. He said it was simple - look at the instruments. Bring the wings level, then the pitch level. Although simple, your body screams at you that it's wrong. He carried with him a steel pipe, so he could beat a student unconscious who panicked and would not let go of the controls. This was against regulation, but he wasn't going to let a student pilot kill him. When JFKjr's crash was on the evening news, he said two words - "spacial disorientation". Months later, that was the official cause.
    - tjohns 11mo ago
      > He carried with him a steel pipe, so he could beat a student unconscious who panicked and would not let go of the controls. Most flight instructors just keep a spare pen in their pocket to jab an uncooperative student in thigh with. (Thankfully almost never used.)
      - WalterBright 11mo ago
        His jets were tandem, so he was behind the student. A steel pipe was the only way.
- deleted 11mo ago
  [deleted]
- prmoustache 11mo ago
  they were disoriented because a sensor was frozen or something like that and the readings were not correct if I remember correctly, an automatic system would have received the same wrong information.
  - WalterBright 11mo ago
    Since the captain recognized the problem and took corrective action immediately, the avionics could have done so, too.

Mawr 11mo ago

Let go of the controls.

DarmokJalad1701 11mo ago

Most modern avionics stacks have one. Examples: - https://www.garmin.com/en-US/blog/aviation/blue-button-helping-keep-blue-side/ https://www.garmin.com/en-US/blog/aviation/blue-button-helpi... - https://pilotsupport.avidyne.com/kb/article/50-dfc90-wings-level/ https://pilotsupport.avidyne.com/kb/article/50-dfc90-wings-l...