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Posted by avestura 2 days ago

If a pilot ejects, what is the autopilot programmed to do? (2018)(aviation.stackexchange.com)
81 points | 67 comments
jcul 2 days ago|
> The only victim of the accident was Wim Delaere, a computer science student reported to have been either 18 or 19 years old.[4][5][1] He was sleeping alone after celebrating the end of his university exams the previous day when the MiG crashed and killed him at 10:30 am. His mother and brother were shopping for groceries in Kortrijk, and his father was working in Ypres.[4]

From the linked Wikipedia article on one of the answers.

What an unlucky kid.

https://en.wikipedia.org/wiki/1989_Belgium_MiG-23_crash

ortusdux 2 days ago||
I recently learned about the Green Ramp disaster, where the crew ejected from an F-16 under full afterburner, and the jet continued on to collide with several parked airplanes, resulting in 24 fatalities.

"As of 2025, this incident has the largest number of ground fatalities for an accidental crash of an aircraft on U.S. soil. It was also the worst peacetime loss of life suffered by the division since the end of World War II."

https://en.wikipedia.org/wiki/Green_Ramp_disaster

Spooky23 2 days ago||
This thread is a great example of how engineers by nature are tempted to add complexity to nearly any scenario.
hex4def6 2 days ago||
It seems like the sensible thing to do would be to fry / erase any IFF and encryption related stuff, but otherwise continue as before.

E.g, if it's already been programmed to fly straight and level, continue to do that. If it's deactivated, stay deactivated.

Just seems like a whole 'nother set of characteristics to test otherwise, as well as adding extra unpredictability. The aircraft is probably damaged / on fire, so its flight characteristics are already going to be extremely different to normal. The best thing in the moment may be to let the aircraft lawn-dart in a field, rather than attempt to get straight and level, and in the process potentially fly over inhabited area or towards a friendly set of aircraft / buildings / vehicles.

pdonis 2 days ago|
If the autopilot is engaged, the pilot won't be ejecting, because the aircraft will be in some kind of controlled flight. Autopilots will be disengaging and lighting up a big red light in the cockpit well before the aircraft gets to the point where the pilot would consider ejecting. Remember that ejecting is an absolute last resort, since the pilot is quite likely to be injured and runs a significant risk of being killed in the process of ejecting.
LorenPechtel 1 day ago|||
Disagree--it can be entirely sane to eject from a fully functional aircraft.

1) Something is going catastrophically wrong with the plane. It's flying now, but soon that fire will burn through the hydraulics, safer to punch while it's still in controlled flight.

2) There is not enough fuel to put it on a runway. Once again, punch while it's still stable. We've even seen a civilian do that--ferry flight with one of those planes with an integrated parachute. He had a fancy rig with extra fuel in the cabin, it wouldn't feed. Without it he wasn't going to make Hawaii.

3) We have seen a Navy pilot correctly punch from a fully functional aircraft. He was on final when somebody launched an SM-2 at him. Low, slow, defenses off--no chance, he punched. He was pointed right at the carrier at the time, having an autopilot do something else would be a good idea. (There would always be a chance that the missile was destructed in time.)

And with semi-functional planes:

4) We have seen an Israeli pilot bring their bird back with one wing. He had to land very hot but there was a long enough runway, he was able to do it. But what if it's even worse? There can be enough damage that your minimum airspeed is above any runway you can reach or above what your wheels can handle. Or maybe the Navy would prefer the pilot to eject rather than risking a major mishap on the deck.

5) What if the problem is elsewhere? We have seen a pilot punch from an apparently-functional F-35. The problem was actually in his controls. (Yes, he has been found wrong--the first two investigations cleared him (if the plane is not responding properly to pilot inputs below 6,000' AGL, eject), they finally found a panel that would declare him wrong. Doesn't make him wrong.)

trenchpilgrim 1 day ago|||
In re: 4 - during desert storm Lt Patrick Olson managed to bring a damaged A-10 back to base. He attempted to land, but his damaged hydraulics were insufficient and the plane cartwheeled, landing upside down resulting in pilot death. It is likely Lt Olson would have survived by ejecting near the base in a designated area, and this became SOP for that category of failure afterwards.

I also recall reading about another damaged A-10 in the same conflict that managed to touch down only to discover the brakes didn't work. Pilot overran the runway but survived. Can't recall pilot's name off the top of my head.

cluckindan 2 days ago|||
About one in 20 ejections results in death, usually due to low altitude, or being hit/crushed by the seat.

Compare to 20 in 20 jet airplane crashes resulting in death and suddenly pulling that lever might seem a worthwhile risk to take

pdonis 2 days ago||
> About one in 20 ejections results in death

But more than that result in injury. The possible injuries are pretty severe.

> Compare to 20 in 20 jet airplane crashes resulting in death

Crashes if the plane is totally uncontrollable, probably yes.

But there's a lot of gray area in between "totally uncontrollable" and "controllable enough that an autopilot can fly the plane". There are plenty of cases where a pilot was able to make a controlled enough crash that they walked away from it, even though the plane itself was totalled.

And once we get to the point of "controllable enough that an autopilot can fly the plane", the pilot would have no reason to eject--because the plane is controllable enough that the autopilot can fly it. Which means whatever problems exist can't be very severe--or the autopilot would be disengaging, because it needs things to be working pretty well to fly the plane at all. That was the point of my response in the GP to this post.

SoftTalker 2 days ago||
A pilot would only eject if the aircraft was uncontrollable with no reasonable hope for recovery. Unlikely the autopilot can do anything deliberate at that point.
RobotToaster 2 days ago||
Planes that keep flying after an ejection do happen

https://en.wikipedia.org/wiki/Cornfield_Bomber

https://www.marinecorpstimes.com/news/your-marine-corps/2024...

tekla 2 days ago||
These are not equivalent.

The first one, the Airplane was in an uncontrolled spin, the ejection happened to fix it.

tgsovlerkhgsel 2 days ago|||
At the very least, something to keep the flight path predictable would make sense, to give the pilot a chance to point the plane at a "safe" area to crash in before pulling the lever. I remember reading several stories of pilots taking "where is the plane going to crash" into account for their ejection decision or last moves before ejection.

There were also several incidents where a pilot ejected because the plane was somewhat controllable but it was clear it couldn't be landed safely. At least one of them where they had tens of minutes of controlled flight before ejecting (they flew it over the ocean to minimize the risk of collateral damage).

bravoetch 2 days ago|||
Unlikely, you say? That's why it's being discussed. Like, if a pilot ejected because the engines stop, but the control surfaces still work... Maybe the plane avoids a kindergarten on its dive to the earth-sky interface.
the__alchemist 2 days ago|||
Not necessarily. For example, you'd eject if unable to get as safe landing configuration.
quotemstr 2 days ago|||
Yes, but the autopilot should have some kind of contingency programming in case the pilot is mistaken about the aircraft being unflyable.
appreciatorBus 2 days ago|||
If this was possible it would just be part of regular flight control laws and would be used to avoid becoming uncontrollable in the first place.
quotemstr 2 days ago||
Huh? If I'm the human pilot, I can pull the ejection lever for multiple reasons, including my just being an idiot. The plane, after I eject, should do something reasonable. Maybe it

* starts broadcasting a mayday?

* crashes into the nearest large body of water?

* attempts to fly itself back to base (we have the technology)?

I mean, it has to do something and flying straight and level until it runs out of fuel is unlikely to be the optimal value of "something"

Why would it be controversial to say "Look, guys, we should decide what the plane does after the pilot ejects. Maybe the best policy is just flying same course and speed until fuel exhaustion, but we should choose this policy, not default into it without consideration."

dragonwriter 2 days ago|||
> The plane, after I eject, should do something reasonable.

There’s a good chance that it can't, and its not impossible that trying to do something reasonable combined with damage that led to and/or resulted from ejection could make things worse.

> starts broadcasting a mayday?

Great idea for peacetime over the homeland, maybe a very bad idea for military operations over contested or enemy territory.

> crashes into the nearest large body of water?

> attempts to fly itself back to base (we have the technology)?

If either of these are useful in a nontrivial share of ejections (except perhaps the former in conditions where it takes no special effort), then there is a serious problem with the training of the people pulling ejection handles and that needs to be fixed, rendering the action not valuable.

> Why would it be controversial to say "Look, guys, we should decide what the plane does after the pilot ejects. Maybe the best policy is just flying same course and speed until fuel exhaustion, but we should choose this policy, not default into it without consideration."

Because ejection is an action chosen when you can no longer meaningfully say what the plane does in any significant way. That’s the whole purpose. If it it is useful to address this question then you have a bigger problem that you need to urgently fix first.

SoftTalker 2 days ago||||
Ejecting for for no reason would end the pilot's flying career. Ejecting for any reason will result in an investigation, at minimum. Pilots are expected to fly the airplane until the last extremity.

So while yes it's possible, it's unlikely, and the return on investment of making the plane able to do something like "return to base" in that circumstance would be a large negative number.

throwup238 2 days ago|||
Even ejecting with good reason is enough to end a fighter pilot’s career. The rates for significant back injury are between 1 in 3 and 1 in 2 depending on the design.
WheatMillington 2 days ago|||
Do you realise we're dealing with humans? Humans who make decisions based on a multitude of factors, or sometimes none at all?
SoftTalker 2 days ago||
Yes, but flying aircraft with ejection seats is demanding work and few humans are capable or qualified to do it. Most people can barely manage to drive cars safely.
Merad 2 days ago||||
I dunno, the current approach seems quite reasonable. In the grand scheme of things the overwhelming majority of the Earth's surface is empty space where a plane crash is unlikely to cause much damage. You also have the complication that military pilots usually try to make sure their plane will crash in a "safe" area before they eject - many have died because they waited too long to eject trying to avoid a populated area. Giving the plan a mind of its own after they pull the handle would be unlikely to go over very well. I believe the scenario of a pilot ejecting from a perfectly good plane that keeps flying for more than a few seconds has only happened perhaps a dozen times in the entire history of aviation? Not really worth worrying about.
jvanderbot 2 days ago||||
I'll do my best. So you want to dedicate probably the rest of your career to automated diagnosis and recovery from crash conditions after ejection? Just so we can say we did a reasonable thing? Oh just the one case where the pilot rejects during level controlled flight you're saying we should be careful to let it continue on same course and speed? And if it's slightly changing course speed or altitude? Did we want to level out or continue the climb and turn? Do we attempt to maintain rate of climb even if it means throttling up? Descent?

The whole thing is so wildly ambiguous and niche that it's a black hole. When a pilot ejects the controller is gone. The controls are slack and it's just physics until fire.

appreciatorBus 2 days ago||||
If we had the technology to fly the aircraft back to base then there wouldn't be an ejection handle, there would be a "fly the aircraft back to base" button.
ratelimitsteve 2 days ago|||
remember that part of optimization is the amount of resources spent developing a solution for a problem that just doesn't come up that often. in the microcosm of a single ejection there's probably a better way to handle it than to just let the plane continue on its course. in the macrocosm, there's probably better problems to deal with than the one that results from the relatively rare situation in the military and unheard of in the civilian sphere. it's also worth noting that ejector seats are explosive-assisted and any plane that's been ejected from is rendered structurally unreliable, and usually is so close to crashing that nothing can be done to save it even if saving it is viable. So most of what you do "in response" to an ejection isn't actually in response, it's about planning ahead. outside of a wartime situation where factors beyond your control tell you where you'll be flying, don't be in a place where it would be dangerous to bail if you think you might have to bail.
jon-wood 2 days ago|||
Even in that case this is a military aircraft, one of the most highly prized secrets many nations hold. Probably the most reasonable response to an ejection the aircraft could take is to nose dive into the ground and slam the throttle to afterburners, which isn’t far of what will happen naturally as soon as the pilot isn’t asking the plane to stay straight and level.
yetihehe 1 day ago||
Maybe the best case would be to disintegrate into small mostly harmless pieces, that won't travel too fast.
whycome 2 days ago||
This is silly. And not true. There is no “would” other than your own prediction. What if the pilot deliberately wanted to crash the plane but not do it intentionally?
the__alchemist 2 days ago||
If it's a controlled ejection scenario, you try to fly to a specific location, airspeed, heading, and altitude, then pull. It will be in your local-area in-flight guide. The intent is, the plane ends up somewhere away from civilization. This if, of course, only suitable for scenarios where you have this luxury.
ternus 2 days ago||
I was astonished at the claim that pilots ejecting can lose half an inch of height due to spinal compression induced by the G-forces. Claims seem to be borne out:

https://www.forcesnews.com/news/can-ejecting-aircraft-make-p... https://www.quora.com/Do-pilots-lose-height-when-they-eject-...

ern 2 days ago|
Making sure that the consequences are well-publicized also has the useful side-effect of making sure that ejection is regarded as a last resort.
ffb7c5 2 days ago||
I think we should make an API call to an LLM with the current GPS location to decide what to do, bonus points if we can mount a forward facing camera and upload the picture as well
bragr 2 days ago||
The analysis and conclusions of the responders here (2018) seem pretty invalidated by the 2024 F-35B ejection incident. Maybe more thought should be put into what the autopilot should do?

https://www.marinecorpstimes.com/news/your-marine-corps/2024...

appreciatorBus 1 day ago|
A single incident doesn’t invalidate anything. No one has argued that it’s impossible for a fighter to fly on for a significant period of time in good shape after a pilot ejects, or the pilot has never ejected mistakenly out of an air worthy aircraft. Rather the argument is that this is a vanishing rare occurrence and the complexities of trying to implement an unmanned auto pilot of a potentially damaged aircraft are probably not worth the handful of times it might be used. One incident doesn’t disprove that it’s vanishingly rare.
dang 1 day ago|
Discussed at the time (of the article):

If a pilot ejects, what is the autopilot programmed to do? - https://news.ycombinator.com/item?id=17391550 - June 2018 (76 comments)

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