NTSB begins probe of chopper collision

FLAGSTAFF, Ariz., July 1 (UPI) -- Federal investigators are trying to determine why two helicopter pilots did not spot each other on a calm clear day in Arizona, colliding in a deadly crash.

Only one person survived the in-flight collision Sunday near a Flagstaff hospital, with six people dead. Both helicopters were headed to the Flagstaff Medical Center.

The 13-member team from the National Transportation Safety Board was expected to begin work Tuesday, The Arizona Republic said. The evidence includes wreckage, radio communications and videotape from a surveillance camera in the hospital parking lot, which is being sent to the NTSB forensics lab.

"The question is why they didn't see each other," NTSB Chairman Mark

Rosenker said Monday. "We hopefully will learn that and prevent this sort of thing from happening in the future."

The dead included a 26-year-old Montana firefighter who had been injured fighting a blaze on the North Rim of the Grand Canyon.