Thanks for the video posts above. The F-86 crash was Steve Schneider ... the same Steve Schneider who started the new-build Me 262 effort that resulted in the Stormbirds units that fly today.
The other videos make a real statement about people who do airshow aerobatics without practice. The video that doesn't work anymore was of a Bell P-63 that crashed doing a loop. The Spifire was doing EXACTLY the same thing.
The engines are good for so much power, and both the pilots of the Spitfire and the P-63 were attempting low-altitude loops at very reduced power. That is they pulled up into a normal loop, but were flying at half or so power. They got the pull-up they wanted because both had approached the loop from a shallow dive, but didn't use the power required to give them altitude for the pull out.
There is a video of a P-38 crash in the UK where the pilot is doing a fast low pass, starts a roll, and hits the ground.
If you come to see the Chino airshow (first weekend of May, May 3 - 4) you will see a great airshow with safety first as the attitude. For warbirds, we don't allow rolls from other than a climbing attitude unless the aircraft has first completed a vertical half loop. That is, a downward roll from the top of a Cuban eight is allowed since there is sufficient altitude, but a flat roll in a low pass is not allowed. Birds start arriving on Thursday and we fly the practice show on Friday. If the air boss (usually Jim Dale) sees anything he doesn't like, he makes a change and they fly it again until he thinks it is safe. That happens before Saturday.
Most of the above accidents in the videos were caused by people who didn't practice the show in front of the air boss, did rolling or looping maneuvers at reduced power to "conserve" the engine, rolled from a level pass without a pull-up, and were flat out of practice at aerobatics. In Steve Schneider's case, I was not there, but have many friend who were. They said he flew the loop at greatly reduced power. Steve's Sabre had solid leading edges (no slats) and had no extra lift capacity left when he tried to pull up at the last second. In fact, at almost looks like it stalled at the last second as Steve pulled harder.
All these can be easily corrected by having the air boss ask in a pilot's meeting what power settings you will be using before practice. A wrong answer means you get some counsel. If it doesn't look like you are actually USING the adjusted power settings, you don't get to fly the weekend show. You also must acknowledge in the pilot's meeting that all rolling maneuvers below the hard deck altitude will be initiated from a climbing attitude, with at least a 15° climb before the roll starts. These "rules" are NOT for everyone, but apply to warbirds, specifically because warbords are NOT aerobatic planes. They are planes that CAN do aerobatics of the positive type and maybe some mild negative ones, but they are not intended as aerobatic aircraft.
So there IS a safe way to do it and we only wish everyone would take the safe route.
Here is a short video of Steve Hinton at the Hemet-Ryan airshow doing aerobatics in the P-38.
View: https://www.youtube.com/watch?v=gYNhWSt-GXU
Notice there are no rolling maneuvers that are on a down line unless he just completed a half loop and is well above the hard deck. When he initiates a roll from a low pass, he has already pulled up to allow for a safe roll. When he loops notice he flies a considerable vertical up line before pulling back to get to the top of the loop, and he does it at enough power to ensure a safe altitude gain in the first half of the loop.
Warbird aerobatics CAN be safe and still look very good. There is no need to push the envelope as there might be in something like the Paris airshow when millions of dollars of sales hang on the display. The warbirds doing airshows are already owned and there is not a large sales population of them hanging in the balance.
Might was well do it safe and practice enough to do it right before the public sees the airshow in the first place. Good airshows MAKE it happen that way (at least the air bosses do) or you don't get to fly in them.