Probably compulsory in competition aerobatics, but I certainly have done Stearman and Pitts loops and rolls without. It would almost certainly be a rule of the governing authority rather than the CAA.

The Yak had bucket seats so you had to wear a military chute or you had nowhere to sit. Can’t say I ever relished the thought of jumping out though.

Can’t see one being much use in a C152 Aerobat. :confused:

Moggy