The Federal Aviation Administration said on Monday that it was investigating a crash after a stunt that called for two pilots to parachute from nose-diving planes and swap cockpits in midair.
The stunt, which featured the pilots and skydivers, was a success and no one was hurt. They were going to send their single-engine Cessna 182 planes into a nosedive and then switch planes midair.
The F.A.A said in a statement that one of the pilots landed by parachute after his plane spun out of control. The other pilot landed his plane safely after regaining control. The F.A.A. didn't say which pilots landed by parachute.
The Red Bull event was a first-of-its-kind jump. Red Bull did not respond to questions on Monday.
The F.A.A. denied the request for an exemption from federal regulations. During the swap, both aircraft will be empty, so Mr. Aikins requested the exemption.
In a reply dated April 22 and signed by Robert C. Carty, the deputy executive director for flight standards service at the F.A.A., the agency said that granting an exemption would not be in the public interest.
Red Bull said that Mr. Aikins and Mr. Farrington are cousins and third-generation pilots who have completed more than 5,000 jumps together.
Red Bull said the men grew up on an airfield and both took their first solo flights at the age of 16.
The planes were equipped with custom-built autopilot systems so they could remain on the correct trajectory for the stunt. The skydivers could catch up to the planes if they had a speed brake and larger wheels on them.
Red Bull said the autopilot would engage once the pilots entered the nosedives. Red Bull said the men planned to jump from the other plane to 2,000 feet above the ground.
Mr. Aikins has drawn media attention before for his skydiving exploits. He was the first person to attempt a skydive without a parachute or wingsuit.
His dive began at an altitude of 25,000 feet, just short of the summit of Mount Everest. He landed on a net that was half the size of a football field.