A federal investigation into the crash of a vintage military jet during a July 4 celebration in Tehachapi, Calif., is trying to determine if the pilots violated altitude requirements and improperly passed over densely populated areas.
Federal Aviation Administration officials said Tuesday that three Soviet bloc trainers had been flying in formation during the celebration when one suddenly veered off, flew over a park and slammed into Old Town Road, missing nearby houses.
The impact killed pilots David Zweigle 42, the city's airport manager, and Robert Chamberlain, 63, of Morrison, Colo., a retired airline pilot and former U.S. Air Force test pilot, who set numerous records in the B-1B bomber. Zweigle owned the restored Aero Vodochody L-29 Delfin, a 1960s-era jet built in Czechoslovakia.
Ian Gregor, an FAA spokesman in Los Angeles, said the pilots had not applied for nor received clearances to fly over populated areas for the Tehachapi celebration that was attended by hundreds of people.
Gregor said special permission may have been required for the L-29s because they are designated by the FAA as "experimental, exhibition" planes, which generally are prohibited from flying over densely populated areas except for takeoffs and landings.
The designation is a safety measure and assigned to aircraft that are neither built to U.S. standards nor assembled at FAA certified factories.
As part of the agency's investigation, Gregor also said FAA officials are interviewing witnesses and reviewing a videotape to determine whether the pilots were flying below the minimum required altitude of 1,000 feet.
"Speaking generally, both these things are serious," Gregor said. "Violations of this nature would merit a penalty on the higher end of the scale." Those penalties include suspensions and revocations of pilot's licenses.
Douglas E. Gilliss, a veteran pilot who flew one of the L-29s at Tehachapi, defended the flights, saying the planes avoided populated areas and flew between 1,200 and 1,500 feet, well above the minimum required altitude. Gilliss flies with the Thunder Delfins, a group of L-29 enthusiasts.
Gilliss said the L-29s flew along the area's railroad tracks and not directly over the city of about 35,000. "This is a standard display up there. We've done them without a gripe from anyone," said Gilliss, who lives in San Diego County.
"We didn't present any hazard to the public and the flights were in the spirit of FAA regulations that encourage the exhibition of experimental aircraft."