What happened
On the day of the accident, a Convair CV-990-30A-5, registered N711NA, was completing a test mission over Monterey Bay. The aircraft, operated by NASA, carried three crew members and eight scientists. As the flight approached Moffett Air Force Base, air traffic control initially cleared the aircraft to land on runway 32R while it was seven miles from the field.
Simultaneously, another aircraft was conducting a local training flight with six people on board. The crew of this second aircraft notified air traffic control that they were joining the approach path for runway 32L. Following this notification, the controller issued a landing clearance for the N711NA to use runway 32L instead of its original assignment.
While descending at approximately 300 feet, the nose gear of the Convair CV-990-30A-5 made contact with the tail section of the training aircraft. The impact caused both planes to lose control, leading them to crash into the Sunnyvale golf course roughly 0.3 miles before the runway threshold. The accident resulted in 16 fatalities and one serious injury.
Findings
Investigations revealed that the collision was driven by multiple errors made by the approach controller. The controller had assigned different landing runways to the two aircraft but subsequently cleared the NASA crew to land on the same runway (32L) as the training flight. The investigation noted that the crew of the Convair did not seek clarification regarding the change in landing assignment, and neither flight crew was able to visually identify or avoid the other aircraft before the impact.