This article is from the Aviation Aerobatics FAQ, by Dr. Guenther Eichhorn with numerous contributions by others.
Wearing parachutes for aerobatics flying is regulated in FAR 91.307. It
specifies that whenever you carry a passenger, you may not exceed 60 degrees
of bank or 30 degrees of pitch up or pitch down unless both occupants wear an
approved parachute. This means that you do not have to wear a parachute when
you fly alone. It does not say anything about aerobatics, it just specifies
the bank and pitch limits. So any maneuver that exceeds these limits falls
under this rule and requires you and your passenger to wear a parachute.
 
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