2 ms·

How does a pilot switch between the three modes? Just switches on the dash?

selectodude 1y ago
It automatically downgrades modes as sensors break. You can force into alternate law by pulling some fuses if you really want to.
ahartmetz 1y ago
As I understand it, there are no switches because pilots aren't supposed to switch modes, but if necessary, pulling certain circuit breakers will disable subsystems whose failure triggers alternate law. And AFAIU it is documented which breakers are "least unsafe" to use that way.
foxyv 1y ago
This is a very "Don't do this" kind of situation but you can force the computer to switch to a different law by pulling circuit breakers for certain instruments. Typically though it will happen automatically when the computer detects sensor failures. Changing the law of the aircraft is something you REALLY do not want to do. It's a "The Airplane broke real bad, do that pilot thing!" situation. Especially on a fighter jet with relaxed stability. https://www.airliners.net/forum/viewtopic.php?t=748133 https://www.airliners.net/forum/viewtopic.php?t=748133 Some fighters have an "EFCS" switch which will switch laws. This can be used during "I'm going to fly into the ground" or "I'm losing this dogfight" situations. Typically this means you are going to be scrapping the airframe soon one way or another.
- megaloblasto 1y ago
  Very interesting. Reminds me of 2001 a space odyssey when the pilot unplugs parts of Hals brain in order to regain control over the ship.
- mikrotikker 1y ago
  Ah is this what the "cobra button" is effectively?
  - foxyv 1y ago
    Yeah, in the Su-27 Flanker that is exactly what it is. You change the flight controls to direct control so you can do things that will put the airplane in an unsafe condition. I think it's a switch in the Flanker as well. In jets like the F-22 Raptor it will just "cobra" with stick input. They will dump the wing controls automatically to unload the wings, and use thrust vectoring to reach absurd angles of attack. The F-18 Hornet uses a paddle switch which will increase the G-limiter and allow spin recovery.
ssalazar 1y ago
This blog post (and blog in general) has some detailed descriptions of different control laws, how they are activated, and how they contributed to the conditions of this particular crash: https://admiralcloudberg.medium.com/trial-by-fire-the-crash-of-aeroflot-flight-1492-ee61cebcf6ec https://admiralcloudberg.medium.com/trial-by-fire-the-crash-... The above post is focused on a Sukhoi jet, with some comparison to Airbus' design, but they also cover Airbus in another post: https://admiralcloudberg.medium.com/the-long-way-down-the-crash-of-air-france-flight-447-8a7678c37982 https://admiralcloudberg.medium.com/the-long-way-down-the-cr...

It automatically downgrades modes as sensors break. You can force into alternate law by pulling some fuses if you really want to.

ahartmetz 1y ago

As I understand it, there are no switches because pilots aren't supposed to switch modes, but if necessary, pulling certain circuit breakers will disable subsystems whose failure triggers alternate law. And AFAIU it is documented which breakers are "least unsafe" to use that way.

foxyv 1y ago

This is a very "Don't do this" kind of situation but you can force the computer to switch to a different law by pulling circuit breakers for certain instruments. Typically though it will happen automatically when the computer detects sensor failures. Changing the law of the aircraft is something you REALLY do not want to do. It's a "The Airplane broke real bad, do that pilot thing!" situation. Especially on a fighter jet with relaxed stability. https://www.airliners.net/forum/viewtopic.php?t=748133 https://www.airliners.net/forum/viewtopic.php?t=748133 Some fighters have an "EFCS" switch which will switch laws. This can be used during "I'm going to fly into the ground" or "I'm losing this dogfight" situations. Typically this means you are going to be scrapping the airframe soon one way or another.

megaloblasto 1y ago
Very interesting. Reminds me of 2001 a space odyssey when the pilot unplugs parts of Hals brain in order to regain control over the ship.
mikrotikker 1y ago
Ah is this what the "cobra button" is effectively?
- foxyv 1y ago
  Yeah, in the Su-27 Flanker that is exactly what it is. You change the flight controls to direct control so you can do things that will put the airplane in an unsafe condition. I think it's a switch in the Flanker as well. In jets like the F-22 Raptor it will just "cobra" with stick input. They will dump the wing controls automatically to unload the wings, and use thrust vectoring to reach absurd angles of attack. The F-18 Hornet uses a paddle switch which will increase the G-limiter and allow spin recovery.

ssalazar 1y ago

This blog post (and blog in general) has some detailed descriptions of different control laws, how they are activated, and how they contributed to the conditions of this particular crash: https://admiralcloudberg.medium.com/trial-by-fire-the-crash-of-aeroflot-flight-1492-ee61cebcf6ec https://admiralcloudberg.medium.com/trial-by-fire-the-crash-... The above post is focused on a Sukhoi jet, with some comparison to Airbus' design, but they also cover Airbus in another post: https://admiralcloudberg.medium.com/the-long-way-down-the-crash-of-air-france-flight-447-8a7678c37982 https://admiralcloudberg.medium.com/the-long-way-down-the-cr...