BBC news here.
Jet fighter crashes into the A27 in the south of England, killing 7 people.
The road is near my company’s HQ, I drive it on a few times a year. Would have been busy with holidaymakers and such headed for the south coast.
Mass, you have to remember the mass. Get it going and it wants to keep going that same direction when you really wish you could change directions faster.
Some F-4, F-105 & other pilots in Vietnam forgot that.
There is a good shot of a F-16 Thunderbird pilot that ejected just before his plane impacted that you have probably seen on the net.
This Brit pilot may also had some other problems, compressor stall, top of the maneuver looked really slow. Bad about all the human suffering from this.
Hope they find a definitive cause.
Need to remember that as the weight goes up, the amount of wings needed to change directions goes up and if you add in stalling the wing, you get a very bad day.
Kind of the same problems as a car traveling fast on a road, having to change directions fast , does not always work. 10 X worse in fast fighter jets.
Or I could be totally wrong. Been known to happen. ( I am just an old alive pilot. )
I witnessed this crash at MCAS El Toro, from not to different an angle from the one shown in the video. In the video, you can see where he stalls at the top.
Apparently the pilot survived so there is a small possibility he’ll be able to recall what happened. I don’t know what manoeuvre he was intending to do but the quarter roll on the way up may have robbed him of some height.
This photo is quite remarkable.
LSL Guy, you have fighter time IIRC.
Would like some opinions:
At what point did he probably know he was in deep dodo?
Could he have bailed out of one of those birds? ( no opinion on wither he should or shouldn’t in my question, I know Nada about that particular aircraft. ) Just could he?
At the end, has the ability to pitch up before impact. a) At what point on his decent would he be able to do that? b) What if he thought this out weeks before and decided if it ever happened to him, he would pitch up/go full AB and hope he powered out before ground contact.
If he realized he had goofed, would this fighter or any fighter be able to power out even if you were in a stalled condition even though you are relatively level at the starting instant? How high would the aircraft have to be?
Am I asking the question correctly?
Or, c) Can a fighter jet ( which ones and is this case also ) can power out with or without AB if the pilot can remain at least close to a level condition?
That looked like an old turbo jet engine like in an early T-33 so if he was not already spooled up, how long would it take and from R.P.'s linked picture, I think I see exhaust waves behind his tail pipe, would he, could he have powered out?
d) how likely was a compressor stall and how much time does it take to get power back it it does happen.
I think he had power at thew end but with that particular airplane, he was had before he even got to the top because of lack of altitude necessary for that particular aircraft. IMO
Big iron & fighter pilots, please respond along with anyone else of course. I am really curious, especially about some hanger flying that I have heard over the years, both pro & con.
In other forums there has been a very negative reaction to doing these acrobatics over a busy highway.
England is a populated country, airports tend to be close to highways.
Hard to tell what the actual altitude is at that point. And a still gives us no info about speed and not much about vector. Looking at the whole image the shot was taken from a goodly distance away with a very high telephoto and later enlargement. So he might have been level at 500 feet just flying along nicely, or in a severe high sink rate descent at 100 feet. Just can’t tell.
@Gus: That’s real insightful, but quite a laundry list of questions 
I’m assuming you’re asking mostly ref the Hawker Hunter accident, not the F/A-18 accident **Johnny **linked to. Although they’re similar in many respects. Here goes, with a bit of comparison between them:
We see the pitch rate really accelerate a bunch shortly after he passes through straight down. That’s him having his *Oh Shit *moment and doing the only thing he could think of: pull back harder. Note that’s the moment he figured it out; he was actually screwed about 60 degrees earlier when he was about 30-40 degrees nose low inverted. That was his last chance to unload, roll upright, and pull upwards and still clear the trees. The big delay between when you *are *screwed vs. when it *looks like *you’re screwed has killed many a fighter (and airshow) pilot. As you alluded to in your first post about mass & speed.
I know zippo about Hawker Hunter ejection systems specifically. But it was a 1950s design, and for seats that old I’d bet he was trapped well before he realized he was in a crack. Even the modern so-called “zero-zero” ejection seats are talking about zero altitude and zero airspeed. Unstated in there is also “zero sink rate.” Being at 2-3000 thousand feet above the ground & descending at 300+ knots is very far from zero sink rate. The F/A-18 guy did have a zero-zero seat and he too was trapped well before he realized his predicament; although not trapped as early as I believe the Hunter guy was.
That famous T-birds F-16 ejection was a different scenario plus a case of perfect timing. He had an engine failure in a dive, then stayed with it until he got the velocity vector (not just the nose) going upwards or nearly so. Then he bailed and just barely got a chute before the ground arrived. Had he jumped earlier at higher altitude but with greater sink rate he’d have hit the ground with no chute yet despite the greater altitude. By waiting to a lower altitude with a better vector he improved his hand. Clear signs of a man who’d done his headwork on the ground and was also very, very cool under pressure. An ounce of preplanning is worth several pounds of Yeagerism. Or so us ordinary fighter schlubs told ourselves.
In non-thrust vectoring aircraft the vast majority of turning force is from the wings. Inward directed thrust at high AOA is nice, but is a pittance by comparison. Where fighters differ from low-speed low-G airplanes is in being able to be (fairly) well-controlled in a partially stalled condition. And in having a wing which stalls gradually rather than all at once. So there’s a pretty big operating envelope while partly stalled; its not the binary stalled/not-stalled world you’re used to.
The key aerodynamic innovation of the F-18 & subsequent fighters is exactly in this very high AOA regime. The Hunter, being a 1950s design, is not nearly so capable in the partial-stall AOA regime & would instantly go into an ape-shit roll/yaw departure if it was fully stalled. We graphically see the difference in the two pilots’ Oh Shit maneuvers. See how much more the F/A-18 was able to rotate his nose versus his flight path at the end game? Neither one was able to alter flight path enough to matter though.
Se this post http://boards.straightdope.com/sdmb/showpost.php?p=17984608&postcount=11 for a discussion of radial G and corner velocity, albeit in a different context. Once those terms make sense …
Typically you’re below corner velocity at the top and will end well above corner velocity at the bottom. So your turn radius will be increasing through most of the maneuver due to that. As well, radial G will be at its most helpful while you’re at the top of the maneuver, and be getting continuously less helpful until you bottom out (ideally before the ground arrives). So radial G also continuously increases your turn radius as the maneuver proceeds.
These two additive factors explain why how these scenarios are so insidious and how highly skilled guys & gals screw up and die. The first 45-60 degrees of the maneuver look like they’re proceeding fine. The next 45-60 degrees look OK, but maybe deteriorating. The last 45-60 degrees look like shit, but you’re already doomed.
For any given aircraft type, altitude, and airspeed at the top of the loop we can calculate how the rest of the maneuver will go if flown perfectly. IIRC after the Thunderbirds fell out of the bottom of a T-38 formation loop en masse they set a limit of 8000 AGL and corner - 50 knots over the top. So that’s probably a decent ballpark for the Hunter.
I’ve never flown an airshow, but I imagine they plan for less than max G, and plan to bottom out at say, 800 feet, planning to actually soften the pull near the bottom to actually bottom out lower, be that 100, 300, or 500 feet as dictated by the show’s rules.
I don’t think it’s really sensible to think of a last-ditch recovery maneuver as distinct from the normal maneuver. You’re doing the same thing in either case, the difference is much more one of degree than of kind. The big thing is to have some pre-decided abort parameters and stick to them.
Up through about 75-80 degrees nose low inverted the optimal recovery is unload, roll upright, then max-G upwards. Past 75-80 degrees nose low the optimal recovery is max G. In either case, you want either idle & max speedbrakes or else max thrust (including max AB if installed) depending on your speed vs. corner. If your nose is damn near straight down and you’re only, say 50 knots below corner, you’re probably better off w idle & speedbrakes since you’re gonna blast through corner pretty quickly anyhow.
Assuming you find yourself in the very last stages of a not-gonna-make-it pullout at max G while holding speed above but near corner, then yes, going full thrust to get some inwardly-directed thrust vector *might *be helpful. But that’s pretty Yeagertastic thinking, and engines aren’t instantly responsive and you’re only a handful of seconds from bottoming out, for good or ill.
A big difference between airshows in 1950s jets and 1990s-or-later jets is the difference in thrust to weight. To put on a good show in a 1950s jet you need to stay fast, well above corner all the time to have enough energy to fly one maneuver after another. The F-16 & later crowd are much more able to rebuild energy quickly between maneuvers and hence can fly a lot more of their show at or below corner. Which make for a more compact show with higher crowd-pleasing angle rates.
The limit case of this is shows in things like Extra 300s & their successors. Insane power to weight, very high G-limits, and low corner speeds produce a show that’s all about high angle rates, continuous high energy maneuvers, and hanging on the prop/thrust.
Once you get into the latest jets, the SU-29s, the Gripen, Typhoon, etc, things get different again. Now they have controllability well past any notion of stall or lift. And with thrust vectoring and high thrust-to-weight (at least with little fuel & no weapons / tanks) they’re almost more of a rocket than they are an airplane. In these jets the same ideas apply, but they’re much more capable of simply pointing the nose where they want to go and using engine thrust to alter their flight path to match where they’re pointed. But they too still have a minimum turn radius achievable and if that curved path doesn’t clear the ground, a smokin’ hole results.
1950s tech, so probably 6-9 seconds from idle to max dry thrust, plus a second or two to light the AB if there is one. Wiki says the Hawker Hunter did not have an AB. As I said in my prior post to RP, we really can’t tell from that still pic where he was in the maneuver. His vertical speed / sink rate is much more important than his altitude / attitude.
A compressor stall is unlikely to be caused by the maneuver and recovery attempt as such. If the whole goof started due to an engine hiccup near the apex he was screwed as soon as he didn’t roll upright. Clearing a developed compressor stall takes anywhere from 10 seconds to a couple minutes. If one was due to engine damage (e.g. blade failure, bird ingestion) it may be unrecoverable even given infinite time.
I agree. He didn’t know that he was below the needed altitude / speed at the apex and was mostly doomed the moment he started down the back side. He had a few moments to realize his error and abort, but for whatever reason did not do so in time.
I doubt Col. Caddick (who survived the crash with serious injuries to fly another day, BTW) ever thought about punching out. He might have thought, ‘Aw, hell. Can’t go into the crowd!’ but I suspect his only thoughts were focused on doing everything to save the airplane. Thanks for mentioning the sink rate. It’s a factor I’ve seldom seen discussed.
Regarding the F/A-18 crash, and from the perspective of a General Aviation pilot, I think the Colonel doomed the maneuver right at the beginning. As I watched the jet pull up I thought, ‘Huh? Is he making a square loop?’ He pulled up that sharply. As seen in the video, his energy was quickly used up and he stalled inverted at the top. Almost recovered, but the sink rate was too high for the remaining altitude.
I feel your pain. See the last quote of mine in you post. ::: sigh ::::
Thanks for a great post that I can understand & learn from.
I had no idea that ‘corner’ speed played such a big part.
A great job from you and Richard on explanations.
I do know the effort and time required to make those kinds of posts.
I have a question about something I used to do that I am not sure I understand why it works and could it work in some of the smaller ‘big iron?’
I’ll write it up in the Johnny’s ‘General Aviation’ thread and if I can make it understandable, maybe you could explain it for me.
:smack: 
That’s Asimovian’s thread.
That bit of highway is where he hit apparently so it’s pretty low at that point. Fair call that it’s not obvious from the photo itself though.
Yes, this ^.
I’ve flown a couple of Pitts Special displays at small fly-ins but was never an airshow regular, I spent a lot of time behind the scenes early in my career though.
I used the below when trying to explain to my mother that an airshow loop with an apparent recovery at 50 feet is not as risky as it looks:
You are in a car, approaching a stop light. You need to be stopped before the intersection. Do you wait until the last minute then slam on the brakes putting the ABS into work and just manage to stop in time? Or do you apply the brakes a little early then when you know everything is well under control, modulate them as required so you stop at the intersection in a controlled manner? Most people would do some version of the latter and the second half of an airshow loop is similar in concept. You do the bulk of the pull through and recovery when you are up high, then once you’re established in a relatively shallow dive you can just fly it back down to 50’.
If you’re still pulling significant g at 100’ then you’re not doing it right. Very low level loops shouldn’t be round either. A round loop, while being the ideal in aerobatic competitions, puts the maximum g at the very bottom which means you have very little performance margin when the bottom of the loop is close to the ground.
This all supposes that you’ve done the first half of the loop in a way that leaves ample room for recovery.
As I said, I didn’t do many, but my own display rules were pretty simple.
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I’m not Patty Wagstaff, Ray Hanna, Bob Hoover etc and should fly comfortably within my own limits, not try to emulate someone else’s.
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All vertical manoeuvres and rolls completed by 500’.
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Never roll inverted and pull through.*
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Stick to the plan. if it’s not working for some reason, abort the display.
The Hunter pilot would’ve had his own personal rules. Maybe he broke one, or they were inadequate, or he might’ve had a physiological problem or mechanical issue.
*I saw this accident just after I got my licence.
Good info & I am jealous of your Pitt’s time. Fun fun…
On the one hand, the Pitts was a LOT of fun. On the other, I don’t miss being out of that scene. Regular fatal crashes of people I knew.
The Civil Aviation Authority has said today that vintage jets, such as the Hawker Hunter that crashed, will be limited to flypasts and not able to perform high-energy aerobatics over land until further notice.
I’m not sure if the suggestion is that this is a ban that they don’t intend to lift.
Which crash is that? The only T-bird F-16 crash I’m aware of is this one, which was caused by some confusion regarding altitude (fourth on the list, “14 September 2003”).
I flew a lot with one of our guys who was part of a two-man Extra 300 team back in the 90s. I asked him why he quit, since the money was awesome.
He said he’d scared himself enough times and everybody he knew who didn’t quit before their peak died in a crash not too long after it.
He was the most mild-mannered cost accountant lookin’ guy you would ever meet. But damn he could fly some serious shit.
Lot of cars queuing on the road, probably from rubbernecks trying to look at the show as they pass. Lot of folks standing by the road, too, trying to watch for free. Probably accounts for the high level of casualties.
In March 2017 the UK AAIB has issued their final report on this accident. See Aircraft Accident Report AAR 1/2017 - G-BXFI, 22 August 2015 - GOV.UK for a summary and links to the full report and supporting documents.
As we speculated a couple years ago, the pilot arrived at the apex of the looping maneuver too low and slow to successfully complete it. But he was unaware of that error until much later in the last half of the loop.
The report also indicates that from the apex and as he started down the back side the pilot had about 4 seconds in which to recognize the error and abort the maneuver. Once past that point he was committed to ground impact.