The pilot of a vintage biplane who died at a Northern California air show was making his second attempt at an upside-down stunt 20 feet off the ground when he crashed, the National Transportation Safety Board said in a report released Monday.

Eddie Andreini, 77, died May 4 in the crash at Travis Air Force Base in Fairfield during the Thunder Over Solano air show before a crowd of about 85,000 people. In the stunt, he had had a knife attached to his plane and was trying to cut a ribbon suspended between two poles held by a ground crew.