[HN Gopher] If a pilot ejects, what is the autopilot programmed ...
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If a pilot ejects, what is the autopilot programmed to do? (2018)
Author : avestura
Score : 68 points
Date : 2025-10-30 21:27 UTC (1 days ago)
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(TXT) w3m dump (aviation.stackexchange.com)
| ortusdux wrote:
| 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
| tekla wrote:
| TLDR: It does nothing and it should never do anything
| darkhorn wrote:
| I think the most proper thing for the jet should be to destroy
| itself. In a war enviornment I would not like my enemy to gain
| intel about my military jets.
| yjftsjthsd-h wrote:
| Not my wheelhouse, but doesn't that involve packing the
| aircraft with explosives, and wouldn't that involve risk of
| blowing up if someone else shoots you? Or is there some better
| way to self-destruct?
| SoftTalker wrote:
| Impacting the ground usually does it.
| DonHopkins wrote:
| Jets are usually full of jet fuel that can blow up if someone
| else shoots you, or they run into the ground.
| klysm wrote:
| Assuming there is an autopilot present, nose diving at max
| afterburner straight down is probably going to yield a
| similar result
| estimator7292 wrote:
| One could calculate the amount of energy in a given amount of
| explosive and smashing into the ground at high velocity. I'm
| too lazy to do so, but I can tell you they're on the same
| scale.
|
| A heavy object moving fast has a _shocking_ amount of energy.
| When such an object impacts the ground, all that energy has
| to go somewhere.
| cosmicgadget wrote:
| There are probably a number of clever and failsafe ways to
| divert jet fuel somewhere that would destroy the plane on
| command.
| miki123211 wrote:
| You could self-destruct just the software / computers by
| encrypting everything with a few keys that are easy to
| destroy.
|
| This is a standard technique for quick and secure data wipes,
| particularly on e.g. modern SSD drives where a traditional
| wipe might be incomplete due to wear leveling algorithms.
| jojobas wrote:
| Would you go near a plane that's an electronic signal away from
| blowing itself up?
|
| Even if mechanical, warplanes get combat damage, and having a
| system like that could make a difference between survivable and
| sure death.
| dylan604 wrote:
| Maybe bring some strong jamming equipment to prevent the
| electronic signal from being received?
| jojobas wrote:
| The signal can originate on the plane itself due to a
| software glitch, stray currents in the grounding skin or
| whatever. If anything, jammers tend to interfere with the
| carrier's electronics itself.
| crazygringo wrote:
| I think its high-speed collision with the ground or ocean
| generally takes care of destroying it. Especially with no pilot
| attempting to keep it level and slow it down and minimize
| damage.
| mikkupikku wrote:
| You could erase computer memory, but blowing up the plane won't
| stop them from gaining intel about the materials, mechanism,
| and whatnot that make up the plane. An explosion won't vaporize
| the airplane, just break it into smallish pieces. Those can be
| collected and analyzed to reconstruct most any detail about the
| construction of the airplane. They even do this with missiles
| and bombs. Even shell fragments. When artillery shells packed
| full of high explosives go off, their intricate fuse mechanisms
| are left remarkably intact.
| the__alchemist wrote:
| 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.
| hex4def6 wrote:
| 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 wrote:
| 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.
| cluckindan wrote:
| 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 wrote:
| _> 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.
| LorenPechtel wrote:
| 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.)
| SoftTalker wrote:
| 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.
| quotemstr wrote:
| Yes, but the autopilot should have some kind of contingency
| programming in case the pilot is mistaken about the aircraft
| being unflyable.
| appreciatorBus wrote:
| 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 wrote:
| 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. "
| SoftTalker wrote:
| 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 wrote:
| 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.
| mikkupikku wrote:
| My understanding is they're automatically retired from
| flight after the second (or maybe third?) ejection, not
| automatically after the first.
| appreciatorBus wrote:
| It feels like a good chunk of the comments here imply
| that ejection is a pretty common activity, hence the
| interest in what happens next, both to the pilot and the
| jet. I don't have any ready statistics, but if ejection
| was a commonplace activity then the world's air forces
| would be depleted of planes in very short order. It
| wouldn't shock me if there's a policy about pilots who
| ejected more than x times, but I would be shocked if the
| policy was ever actually enforced, simply due to the
| rarity of it even being an issue.
| throwup238 wrote:
| The Martin Baker homepage shows 7802 lives saved using
| just their brand of ejection seat so it's not exceedingly
| rare.
|
| I'd estimate less than 5% of fighter jet pilots eject
| during their career.
| WheatMillington wrote:
| Do you realise we're dealing with humans? Humans who make
| decisions based on a multitude of factors, or sometimes
| none at all?
| SoftTalker wrote:
| 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.
| ratelimitsteve wrote:
| 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.
| jvanderbot wrote:
| 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.
| justsomehnguy wrote:
| To add:
|
| If the flight happens in the Grand Canyon?
|
| A tightly populated Grand Canyon?
|
| Tightly populated, divided by multiple not-so-friendly
| nations? Which have nuclear weapons?
| Merad wrote:
| 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.
| dragonwriter wrote:
| > 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_.
| throwaway173738 wrote:
| Yeah it's equivalent to asking what a car should do after
| a 60mph collision. Probably sit still and try not to
| catch fire.
| appreciatorBus wrote:
| 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.
| jon-wood wrote:
| 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.
| RobotToaster wrote:
| 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 wrote:
| These are not equivalent.
|
| The first one, the Airplane was in an uncontrolled spin, the
| ejection happened to fix it.
| whycome wrote:
| 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?
| bravoetch wrote:
| 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.
| LorenPechtel wrote:
| The plane doesn't know this. But this is part of why the ACES
| II seats are capable of zero-zero ejections. One of the
| scenarios in mind is allowing the pilot to steer for the open
| space without making it a suicide mission.
| tgsovlerkhgsel wrote:
| 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).
| the__alchemist wrote:
| Not necessarily. For example, you'd eject if unable to get as
| safe landing configuration.
| cosmicgadget wrote:
| Thinking about this one
| (https://theaviationist.com/2025/02/12/ea-18g-growler-
| crashes...), it seems like after ejection you'd want the plane to
| lawn dart whenever possible. It allows the pilot to know if it is
| an okay place to ditch and it minimizes the reverse engineering
| risk.
|
| I imagine there is a good reason this isn't the way things are
| though.
| Spooky23 wrote:
| This thread is a great example of how engineers by nature are
| tempted to add complexity to nearly any scenario.
| bragr wrote:
| 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 wrote:
| 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.
| ffb7c5 wrote:
| 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
| jcul wrote:
| > 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
| deadbabe wrote:
| His death later inspired the movie Donnie Darko, about a kid in
| 1988 who is killed by a jet engine in similar circumstances.
| PNewling wrote:
| I can't find anything that would suggest this is true, but I
| would love if you were able to link me something proving me
| wrong, as I loved that movie growing up and like reading
| about it still.
| ternus wrote:
| 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 wrote:
| 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.
| varjag wrote:
| You don't really get a rando who would be unaware of that in
| the pilot seat of a fighter jet very often.
| dang wrote:
| 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)
| jayd16 wrote:
| I wonder if dumping the fuel ASAP is a good idea or bad idea.
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