I've read it in reference to helicopter flight. I think it is the period
when you are just starting to gain forward speed and altitude. It's where
you don't have enough of either to autorotate to landing in case of an
engine failure, I think.

mike

"karl gruber" wrote in message
...
I've never heard it about a helicopter......and I'm rated. But I suppose
it could be since everything is weird about helicopter aerodynamics.

"Coffin corner" refers to the narrow band of airspeed between stall and
mach buffet in a jet.