Boeing 777-222 N216UA and Cessna 182R N9870E incident near San Francisco, California

Probable cause

The local controller's issuance of a takeoff clearance to the Boeing 777 without ensuring that approved separation would exist with the Cessna 182. Contributing to the incident were tower procedures that permitted transitioning aircraft to cross the runway 28 departure corridor at low altitude while runways 28L/R were in use.

NTSB analysis

An operational error occurred when a Boeing 777 and a Cessna 182 transiting the Class B surface area passed within approximately 480 feet laterally and 300 feet vertically of each other. Both airplanes were under control of air traffic control at the time of the incident.

Postincident investigation determined that the local controller issued a takeoff clearance to the Boeing 777 without resolving a potential conflict with the Cessna, which was southbound just west of the airport. The controller attempted to establish approved separation between the two airplanes after the Boeing departed, but was unable to do so. The pilot of the Cessna took evasive action to pass behind the Boeing. Review of tower procedures revealed deficiencies that permitted aircraft to cross the runway 28L/R departure corridor while the runways were active, facilitating conflicts of this nature.

Text from the NTSB. Open the NTSB docket for OPS10IA020 for the full record.