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Comment by stefan_ | Hacker News Reader

There is a video of what it sounds like:

https://www.youtube.com/watch?v=WkZGL7RQBVw

That automated recover voice is quite eerie.

This is an incredible video. Hearing the pilot gasp for air while a) his wingmates yell on the radio and b) seeing the details on the HUD are amazing.

The airspeed goes above Mach 1 while the altitude drops from about 16,000 ft to 4,000 ft. The pilot sustains over 9G when the automated system pulls him out of the dive.

Wow!

From what I've read in the past, Auto GCAS computes a 5G recovery pull. Speculation was that the pilot came to consciousness at some point during the recovery and applied some extra input to hit 9Gs.

Pilot recovered while pulling 5G? I'd think they would have designed the GCAS to avoid a crash at all costs, regardless of the Gs required. Crashing is worse

It is designed that way. It realizes that by defining a roll to level and +5G climb as a successful recovery, and preventing the aircraft from being flown into a condition where a successful recovery is impossible.

So if you're flying right above terrain and you suddenly fly down, the airplane should accept your inputs and fly towards terrain until the moment recovery is impossible and will then engage.

This video from the Air Force shows this clearly: https://youtu.be/Wf27X73jxlE?t=144

The system allows you to fly low and fast (2300 feet above ground and 500 mph) until a +5G pull wouldn't get you off the ground, then activation.

Agreed, even if he was conscious during that nose dive, pulling 9.1 G’s would send him right back into GLOC before fully recovering.. and likely into the ground as he was already so low...

Only this computer system could’ve pulled off such a save. Awesome!

how can you read that? I look at your comment and look at the HUD and can't match up any of the numbers and axis to your observations? how do you read this?

They probably used to play flight simulators (I did). The vertical ticker on the left is airspeed in knots. Ticker on the right is altitude in feet. Then underneath the left ticker find the word SIM, directly beneath it is the plane's current mach number, and diagonally below and to the left of that is a counter that tracks the highest G load the plane has sustained (it goes to 8.4 right as the pilot passes out then peaks at 9.1 during the pull out).

Yup! And on the left side, the decimal number above the "C" is the current G on the aircraft, so you can see that number increase as he recovers.

For OP, here's a great guide that ChuckOwl of the DCS community did for the F-16C in game. HUD breakdown is on page 35 of the PDF.

https://www.mudspike.com/chucks-guides-dcs-f-16c-viper/

Yeah, he was already booking it.

This looks like it was an air combat exercise. At the very start of the video (0:07) you see a big round circle and some lines that are spread a the top and close together at the bottom. That's the EEGS gunsight, and in the censored portions of the screen is likely the bandit/hostile he was tracking. (Exercise of course.)

Either his target slips out of gun range or he switches to a different mode, but regardless it looks like he pursues, rolls 90 degrees and "buries the stick in his lap" (F-16 has a side stick that doesn't move, but whatever. =). I'm told you have to be careful with this, and probably in the F-16 doubly so. (As C.W. Lemonine has said in a few of his videos, the F-16 will try to kill you.) In the top left of the HUD, straight up from the "C" is a decimal number showing the Gs on the aircraft, and it climbs rapidly from 3-4G up to 9G. He loses about 100knots of airspeed (still pretty fast though!) but then you hear that exhale around 0:18 and he starts to slip off the horizontal and enter that dive. His 9G turn probably is what knocked him out, and yeah, breaks Mach 1 briefly as he heads downward.

Then as ya said, he pulls another 9G when the system pulls him out of the dive.

The "knock it off" calls after are to indicate that they're not fighting anymore. As I understand, that's not slang, that's the actual terminology used.

Crazy stuff.

> The "knock it off" calls after are to indicate that they're not fighting anymore. As I understand, that's not slang, that's the actual terminology used.

Yeah, AIUI that is essentially the safe word (phrase) that anyone can call at any point that says "everyone involved stop now".

You hear SULLY1 call "SULLY knock it off" (command) and then call out his own confirmation/the now conscious pilot calls the confirmation as well.

The automated one is the female "altitude, altitude, pull up, pull up". The screaming dude is his wingman.

I think it was his wing mate

I guess thats possible, but it seems quite.. regular?

The repeated "Recover!" is indeed the formation leader, not an automated warning. It's as regular as it is because pilots, and especially military pilots, are trained to maintain a very strong radio discipline, and also (as Brian Shul notes in Sled Driver, his SR-71 memoir) because as a point of personal and cultural pride everyone wants to sound like Chuck Yeager on the radio. It makes sense, too; things can go wrong very fast in an airplane, and it does no one any good for a pilot to lose their cool in an emergency.

Listen closely, and you'll notice that the formation leader lets that discipline fray a bit in the second and following calls, when some urgency bleeds through. This is because he suspects his trainee is about to die, which is what would indeed have happened if AGCAS hadn't been available.

(You can also tell it's a radio call and not an annunciator by the form of address - the full call is "Two, recover!"; "Two" is what someone else in the formation calls its second member. "One" is the formation leader; in a four-ship formation you'd also have "Three" and "Four", and so on for larger groups.)

edit: corrected some terminology

> Listen closely, and you'll notice that the element leader lets that discipline fray a bit

Actually, the moment I heard him, I thought there was terror/panic in his voice which is warranted because

> because he suspects his trainee is about to die

came very close. Went from over 16,000 ft to under 5,000 ft.

One thing I did not think was "this is a machine talking".

Yep. The actual AGCAS annunciation is the pair of chevrons advancing from the sides of the HUD into the center, and the blinking cross and "FLYUP" indicates that the system has engaged.

For audio, there's a very noticeable horn during recovery, as well as a "Fly up" automatic voice announcement - that's a little hard to pick up due to overlap with a call from the formation leader, but you can catch it if you listen closely.

There's also an automated (and very calm) voice announcement saying "altitude" 2-3 times before the urgent "fly up!" and horn.

I guessed that he probably suspected he's unconscious or something, and therefore warranted shouting.

After all, the leader had probably seen Top Gun, where this almost happened to Cougar :)

Well yeah, formal radio comms have to be. It's not like Top Gun.

Question: What repercussions does a pilot face after an incident like this? Is there more physical training done do the breathing maneuvers, and plane training to prevent excess G’s like this? Is the pilot grounded for a certain period of time?

Could you please translate what they're saying? I can never understand what people say on radio communications.

It’s interesting to note the blacked out parts of the HUD.

wow, this is making me tear up for some reason. thanks for sharing. i guess i've never seen such a clear case of tech making a life saving impact before.

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