Mark James Boyd wrote:
One flat skidding turn, the others were in a bank. At least one
looks like an aileron spin (this can be done with feet off the rudders
completely, but is very hard to time correctly). Several don't
look like spins at all, but overbanking that led to a steep spiral
close to the ground. In others, it seems possible the steep bank was
after the spin entry, perhaps not before it.

I've witnessed three stall/spin accidents over the years, two gliders
turning base to final, and one power plane during departure. At the
end, all of them looked like a steeply banked turn into the ground.
Most eyewitnesses, particularly non-pilots, aren't going to notice
anything is wrong until after the spin has started, at which point it
will look very much like an abnormally steep turn.

I've also been in a G103 that was about to depart into a spin from a low
shallow left turn after a botched low finish at a contest. I was PIC,
but a CFIG (!) in back was flying. I noticed things were getting a bit
quiet, the left wing was starting to drop, and the stick was moving
toward the right. I reflexively slammed the stick forward, which was
probably what prevented us from making like a cartwheel.

In most gliders (and there are exceptions), when you stall in a turn the
inner wing is going to start dropping. If you release back pressure at
this point, you'll be fine. But, the natural reaction of too many
pilots is to try to pick up the low wing with aileron, which increases
the angle of attack on the already stalled wing, increasing drag and
decreasing lift, resulting in more bank, until the nose drops and you're
spinning for real.

Marc