An error by local air traffic control and possible limitations to the see-and-avoid concept preceded the Aug. 16, 2015 midair between a Rockwell Sabreliner and a Cessna 172 while in the traffic pattern at San Diego Brown Field, according to the just-released NTSB factual report. The accident killed the one person aboard the Cessna and the four persons in the Sabreliner. Weather at the time of the accident was VMC.
The two aircraft collided at about 11 a.m. as the Sabreliner was completing a turn to a right base leg and the Cessna was on an extended right downwind after conducting a touch-and-go. During the time leading up to the collision, the local controller was handling nine aircraft.
Several minutes before the accident, the controller issued a 360-degree turn meant for the Cessna but communicated to the registration number of an aircraft departing the area. When the controller realized the mistake, it was four seconds before the collision and six minutes since any controller had communicated with the Cessna.
The factual report contains a cockpit visual study to examine the ability and limitations of the pilots to see and avoid the other aircraft. It concluded that the aircraft would have been in viewof each other at various moments before the collision, but window posts on both aircraft might have obscured visual observation when the aircraft were 0.1 nm apart. Meanwhile, the Safety Board is holding a hearing today on the safety issues, including the see-and-avoid concept, involved in this accident and another 2015 fatal midair. Both a safety recommendation and a Safety Alert will be released following the hearing.