PHOENIX (AP) -- Federal accident investigators say two single-engine planes were flying in the same direction but then turned toward each other before colliding May 31 and crashing in the desert in north Phoenix, killing all four people aboard.
A National Transportation Safety Board preliminary report says radar data indicates that the planes were about a mile apart before the collision, both flying northerly at about 900 feet above ground level.
It says the planes collided after they simultaneously turned toward each other.
Those killed were two employees of a hot air balloon company in one plane and two flight instructions who work for another company in the other plane.
NTSB investigator Van McKenny says the planes were flying in uncontrolled airspace where separation of aircraft is the responsibility of pilots.