One 2-seat glider at our club is owned by a syndicate with one member who lost his medical. So I get the occasional PIC flight when his partners are unavailable.
In his glider he finds and works the thermals better than I can -- and he does the landings.
The risk of his incapacitation and messing up on the controls in a way I could not remedy is the about the same as with anybody who shows up as an intro or trial flight passenger.
That's what the parachute is for
