See "swiss mishap"
https://www.youtube.com/watch?v=dLBJA8SlH2w
It would seem that this mistake is not as uncommon as many of us would like to believe. I see that the comments below the video run the gamut that we would expect--a lot of armchair quarterbacks, of course, and many deserved kudos to the passenger.
Lawrence
Tandem glider failure to hook in passenger
Re: Tandem glider failure to hook in passenger
I remember while learning HG years ago they also did tandems . One of the things they ALWAYS did was did a hang check with both participants hooked in before launching, someone holding the nose, and both participants lying prone, hanging, full weight on the hang strap(s). This was required every launch (among a few other things) before even thinking of launching.