[Yosemitest]

I disagree. "Pilot Error" started this chain-link of events.

Here's some insight on "Wake Turbulence".

Take a look at this photo, and consider the size of the wake.
Also realize that the wake is behind the aircraft and much larger than the aircraft.
Also realize that the aircraft is probably in level flight at just above landing speed.



Here's another photo to consider.



Realize that the larger vortices at the wingtips are NOT visible in this second photo.




A Mustang P-51 is a CAT III aircraft for wake turbulence. Source is almost at the bottom, after ROCKWELL INTERNATIONAL CORP. (USA)
I don't know what type aircraft were ahead of him, but I assume the similar type aircraft with similar type speeds.
You also know the definition of:
WAKE TURBULENCE- Phenomena resulting from the passage of an aircraft through the atmosphere. The term includes vortices, thrust stream turbulence, jet blast, jet wash, propeller wash, and rotor wash both on the ground and in the air.
You know that a touch and go/low approach (what is closest to the air racing low to the ground) over the same runway requires, When either is a Category III aircraft- 6,000 feet and that's at a normal landing speed.
These racing aircraft were NOT at landing speed.
You're familiar with the AIM, chapter 7, but just in case you want to review it, click here.
But let's review anyway.
... The strength of the vortex is governed by the weight, speed, and shape of the wing of the generating aircraft. The vortex characteristics of any given aircraft can also be changed by extension of flaps or other wing configuring devices as well as by change in speed. However, as the basic factor is weight, the vortex strength increases proportionately. Peak vortex tangential speeds exceeding 300 feet per second have been recorded. ...

1. In rare instances a wake encounter could cause inflight structural damage of catastrophic proportions. However, the usual hazard is associated with induced rolling moments which can exceed the roll-control authority of the encountering aircraft. In flight experiments, aircraft have been intentionally flown directly up trailing vortex cores of larger aircraft. It was shown that the capability of an aircraft to counteract the roll imposed by the wake vortex primarily depends on the wingspan and counter-control responsiveness of the encountering aircraft.

2. Counter control is usually effective and induced roll minimal in cases where the wingspan and ailerons of the encountering aircraft extend beyond the rotational flow field of the vortex. It is more difficult for aircraft with short wingspan (relative to the generating aircraft) to counter the imposed roll induced by vortex flow. Pilots of short span aircraft, even of the high performance type, must be especially alert to vortex encounters.
(See FIG 7-3-2.)



Something else that you probably are aware of is wind's effects on wake turbulence.
But just remember
A crosswind will decrease the lateral movement of the upwind vortex and increase the movement of the downwind vortex. Thus a light wind with a cross runway component of 1 to 5 knots could result in the upwind vortex remaining in the touchdown zone for a period of time and hasten the drift of the downwind vortex toward another runway. (See FIG 7-3-6.) Similarly, a tailwind condition can move the vortices of the preceding aircraft forward into the touchdown zone. THE LIGHT QUARTERING TAILWIND REQUIRES MAXIMUM CAUTION. ... (See FIG 7-3-7.)

The pilot went under someone's wake, when he should have went slightly above that lead aircraft's flight path ("Pilot Error").
It's my guess that when he experienced the roll from the wake, he counter rolled and jerked the plane up.
Then the seat broke, and he let go of the stick, and down it came.
With over 30 years of air traffic control experience, mostly in the military, that's my educated guess.
Never, but never, cross under and inside a high performance aircraft's track.

I'm trying to save lives, here.
Don't get caught up in the "large, heavy" mentality for wake turbulence.
Don't forget about aircraft category classes (CAT I, CAT II, and CAT III).
Also, helicopters can produce some very dangerous wake turbulence, even though they are physically small.
Never, never, NEVER, forget about high performance aircraft. That error will kill you, and your passengers.

What's my point? My point is to consider:

where the "Galloping Ghost was in the race, and how many aircraft were ahead of him.
How many loops had they made around the pylons?
In other words, how tore up was the air where the modified P-51 Mustang first encountered its roll (the point of the wake turbulence encounter)?

[MasterGunner01]

Point is well taken. Wake turbulence does not take mechanical failure into account. There was observed mechanical failure in this case.

I will defer to an experienced retired naval aviator with over 26 years of experience. He saw things happen that were indications of at least one and possibly more mechanical failures.

He saw the P-51 pitch up after it lost its elevator trim tab. It went into a roll that the pilot was not able to stop and he wound-up in a pitch down attitude where he impacted the ground. Game over.