L-29 crash at Argentine Airshow 12/11/23
 

Another low pass and roll goes wrong...

https://aviation-safety.net/wikibase/347812

The L29 seems to have suffered quite a few accidents over the years in civilian use.
Suffering the same fate as the Hunter perhaps. Fast ship in the wrong hands?

Pilots have very likely missed or failed to compute the "enegy gates" to execute the maneuver. I dont know what they intended to do, if it was a barrel roll ( probably not as they interrupted it while inverted unless they were disoriented or incapacitated) or more likely a reverse cuban 8 ( Pull to 45 degrees up pause then pull through then level off) .

For a normal roll even with the "pause" while inverted would have been a non event, they would have ended up upright though nose low with plenty of height available, they had plenty of energy available after that high speed low pass.

But -and here lies the risk- with this same energy to spare on the reverse cuban 8 after inverted the "energy gate" was busted: way too low and fast. Closing that portion of the loop while inverted was impossible, the radius arc ( It increases at the square of the velocity, double the speed quadruple the radius) was too large and there was not enough room to allow for it other than stall under g while pulling to avoid hitting the ground.

When "energy gates" are not considered in advance, any non compliance or improvisation is a big risk, then the maneuver should be aborted; From inverted complete the half roll and recover straight and level. You may well have luck in a light aerobatic Extra aircraft with his quick roll rate and ligher wing loading, but no chance on a heavy underpowered military jet trainer.

The laws of physics are non negotiable. Speed and height did not permit that closure of the maneuver. It should have been aborted.

There is a similar, very similar incident of an italian eurofighter which hit the sea in the same fashion,in Pratica di Mare some years ago, just google for it.

It was much higher that this L29 probably in excess of 10'000 feet but with much higher closing speed it 3-400 knots I would assume, the radius to close the maneuver was immense, and while pulling out agressively with the sea appraching the Eurofighter stalled under heavy G and pancaked, The L29 likewise stalled dropped a wing and flipped.

More than" fast ship in the wrong hands", fast ship without proper training and improvisation.

that is a bit odd. The control authority is there at all times, they convert a simple upward vector aileron roll into a.... whatever that was. The attitude was never high enough to consider doing a half roll and pull through reversal, part of a cuban, but, then they drop the nose and run out of ideas. The last video segment suggests there may have been a very late short duration stall or it was hesitation by the pilot who was seeing the planet coming up quickly in his windshield. Assuming the pilot had any competency in aerobatics, it is a strange flight path. It isn't G-LOC, and if there was an aileron restriction early on while inverted, that cleared prior to impact, so seems odd, unless a harness/control interference may have occurred. Sad outcome.

Wouldn't say it's odd, rather just another in a sad litany of low passes and rolls that have seen the nose drop while inverted followed by an unintentional dive with no way out. Most notorious I can recall is the Biggin Hill Invader in 1980.

Hurricane at Shoreham being another.

Hunter?

The hunter was a slightly different situation, being an unrecovered loop, rather than roll, but similar theme....

DAR, DT2 is referring to a Hurricane crash at the show in 2007, there used to be a video of the event but all I can find now is post crash, occurred during a mock dog fight with a few other participants.


Accident report extract.

I was present at the Hurricane accident but didn't see it, but the video clip I saw looked nearly identical to the Firefly crash at Duxford which I did witness. Both aircraft were being flown fairly conservatively.

I used to feel a bit uneasy watching one pilot loop a vintage fighter apparently somewhat slower than Ray Hanna, Brian Smith, et al tended to do. I'm sure he had speed in hand and probably his mostly flatter displays didn't require quite as much energy management as the other exponents did but it still made me look away. Glad to say he and his aeroplanes are still with us, though he no longer flies displays.

Fair enough, another low level aerobatic crash I did not know about!

Now we are at it, there was a similar SAAB Gripen crash in Thailand a few years ago.

You could also add the Duxford P38 crash although that one goes firmly in the `unexplained` category. Outcome the same.

There was yet another similar looking crash of a T28 in Hungary earlier this year.

The deadliest airshow crash of all time, 77 killed, including 28 children, 543 injured, 100 0f whom were hospitalised, the two pilots survived with minor injuries.

Megan correct me if I'm wrong but did North America and Europe establish more stringent rules regarding no flight paths directly over the crowds.

The pilots stated that the airbase map they had received differed from the actual layout they found at Sknyliv airfield, where they had been also denied an extra rehearsal flight before the show for financial reasons. Although the root cause of the crash was found into the pilots violating the plan and performing “difficult maneuvers they had not done before”, other factors, including a small flying zone and inappropriate zoning by the show organizers who had allowed spectators to gather so close to the flight line were blamed for the tragedy.

The court found the two pilots and three other military officials guilty of failing to follow orders, negligence, and violating flight rules. Two of the three officials were sentenced to up to six years in prison; the third received up to four years, a military court sentenced pilot Volodymyr Toponar and co-pilot Yuriy Yegorov to fourteen and eight years in prison, respectively.

I think the Frecce Tricolari crash at Ramstein tightened up a lot of rules regarding overflights of or manoeuvres towards crowd lines. As far as I know, the Red Arrows still start their display with an overflight from behind the crowd but at 500' or whatever. I recall a foreign Jungmann flying in towards the crowd at a display and pulling up into a stall turn well inside the safety line, commentator Brendan O'Brien saying something like "please don't do that there...". Believe it was the same pilot who died flying the same aircraft during a display in France the following weekend.

The Biggin Hill Invader crash (pilot plus six passengers) triggered a ban on passengers being carried at air displays - nevertheless I've seen two back seaters die in subsequent accidents whose presence may not have been necessary.

Maybe it would be the right thing to think about what these displays are good for? Showing off by individuals? Scare the crowds? Get spectacular pictures for marketing or news? Show aircraft outside of their normal envelope?
These mostly are veteran aircraft and sometimes veteran pilots, some not with military background and not current like say flight instructors on type. The airframes can be old and fatigued and engines limited or just too precious to risk crashing (well, not an L-29).
From my point of view it would be wiser to limit displays to more moderate manoeuvres like takeoff and landings low flybys fast and slow and some moderate turns. Even during their day many military types had their limits and risks why trigger extreme manoeuvres today when the same frames are worn out and old? Look how Shuttleworth's Edwardians got so old.
Without wanting to spoil the fun but with so many historic aircraft crashing and lost I'd prefer a more moderate style. This should be made a regulation. If not by the authorities then by the insurers. I know somebody privately owning (and keeping) a Mustang and what kind of training and experience the insurance requires before a single pattern.

What examples are there of old aircraft crashing because they are old or 'worn out'? The most common single factor appears to be misjudgement of speed and/or altitude at low level, and this can happen to current military pilots as much as anyone else. EG The Mountain Home Thunderbirds crash.