Smoke haze in area
Rumour has it (in the spirit of PPRUNE) that it was as a result of poor visibility on approach.
There had been much autumn burning off in the area with smoke haze.
Possible case of slant visibility problem.
A Grob 109 is a motor glider.
Not sure why a go around and divert/ precautionary landing elsewhere was not done.
Hopefully for those lost, a cause can be determined and lessons learned.
it won’t bring them back, I know.