A witness said the two planes that crashed midair over southern San Diego County, killing five people, took no apparent action to avoid each other, according to a preliminary report from the National Transportation Safety Board released Thursday.
The twin-engine Sabreliner jet and the single-engine Cessna 172 collided Aug. 16 near Brown Field.
All four people on the Sabreliner were killed, as was the pilot in the Cessna.
The NTSB report says that a witness saw the two "flying toward each other" but that they "did not appear to have made any avoidance actions" to avert a collision. The report did not provide a reason for the lack of action.
The Cessna was being flown by a private pilot, an employee of Qualcomm. The Sabreliner, registered to defense contractor BAE, had three company employees and a contractor aboard.
The Sabreliner was returning to Brown Field after completing a test of a radar system for the Navy, officials said. The Cessna was flying away from Brown Field. The general aviation airport is 1.5 miles north of the Mexican border and 13 miles southeast of downtown San Diego.
Debris from the collision was spread over a wide area. The Cessna broke into pieces, and the Sabreliner exploded when it hit the ground, according to the NTSB report.
The wreckage caused a two-acre brush fire near California 125 that was quickly extinguished. No structures were damaged or threatened in the crash, which occurred about 11 a.m.