ºÃÉ«tv

There had been no coordination of altitudes in briefings before the flight or while the planes were in the air, the NTSB said. The report said that the Kingcobra was the third in a formation of three fighters and the B-17 was the lead of a five-ship bomber formation.

Eric Weiss, an NTSB spokesperson, said the agency is trying to determine the sequence of maneuvers that led to the crash. It is also examining whether such air shows normally have altitude deconfliction plans.

“Those are precisely the types of questions our investigators are asking,� Weiss said. “What was the process? What’s the correct process? And what happened?�

John Cox, a former airline captain with more than 50 years’ experience, was surprised that the NTSB found there wasn’t an altitude deconfliction brief before or during the flight. He said these take place in other air shows, but he’s not certain whether they’re standard for the Commemorative Air Force, which put on the Wings over Dallas show.

A person familiar with the show’s operations that day said the air crews were given general altitude direction in their morning pre-show briefing. However, there was not a discussion of specific altitudes for each pass the aircraft were going to perform, said the person, who was not authorized to discuss the matter publicly and did so on condition of anonymity.

Typically fighters fly above bombers, and when a group is called to make a pass that could put planes at the same or nearly the same altitudes, they maintain a lateral separation from each other, the person said. In general, the person continued, it's the responsibility of the air boss to set out a plan for maintaining either vertical or lateral separation.

Wings Over Dallas was the group’s last show of the season, the person said.

The NTSB said the fighter formation had been told by the air boss to proceed to a line that was 500 feet (152 meters) from where the audience was lined up at Dallas Executive Airport, while the bomber formation was told to fly 1,000 feet (304 meters) from the audience viewing area.

The NTSB said a navigation device on the bomber “contained position information relevant to the accident� but a device on the fighter didn’t record during the flight.

The Commemorative Air Force, which put on the show for Veterans Day, said Wednesday that they're continuing to work with the NTSB and are grateful for that agency's “diligence in looking into anything that could have been a factor to cause the accident." The group said they can’t speculate on the crash’s cause.

The Commemorative Air Force previously identified the victims as: Terry Barker, Craig Hutain, Kevin “K5� Michels, Dan Ragan, Leonard “Len� Root and Curt Rowe.

All the men were volunteers who had gone through a strict process of logging hours and training flights and were vetted carefully, Hank Coates, CEO of Commemorative Air Force, said after the crash.

Cox said the planes were flown by experienced pilots and that it’s “virtually certain� the pilot of the smaller, more maneuverable fighter didn’t see the bomber. He said understanding how this happened will be a central challenge for investigators.

"What happened for two pilots of this skill level to end up in the same airspace at the same time?" said Cox, the founder of Safety Operating Systems, which helps smaller airlines and corporate flight services around the world with safety planning.

The air show collision came three years after the that killed seven, and about the safety of shows involving older warplanes.

The B-17, a cornerstone of U.S. air power during World War II, is an immense four-engine bomber that was used in daylight raids against Germany. The Kingcobra, a U.S. fighter, was used mostly by Soviet forces during the war. Most B-17s were scrapped at the end of World War II and only a handful remain today, largely featured at museums and air shows, according to Boeing.

___

Associated Press writer Tara Copp in Washington contributed to this report.

___

Follow AP's full coverage of plane crashes: