Many flight manuals of newer gliders say that a spin will turn in to a spiral dive on its own after a few turns. Spin and spiral dive recovery are, of course, quite different. If you've lost situational awareness enough to inadvertently spin, not noticing the subtle transition from spin to spiral dive might happen too. Also, reading flight manuals, a few of them recommend somewhat different recovery than "standard" that we were all taught.

This has little to do with speculation about this accident, but it's an interesting related fact. Reading the flight manual about spins is a useful winter pastime.

John Cochrane