This February 2009 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
Aircraft: Cessna 172N, Cessna 172S. Injuries: None. Location: Olathe, Kan. Aircraft damage: Substantial.
What reportedly happened: The two airplanes were taxiing to the run-up area. The Cessna 172S, piloted by a private pilot, was cleared to taxi and crossed the active runway. The student pilot aboard the N-model did not obtain proper clearance to depart the ramp for the parallel taxiway, but taxied anyway. The private pilot, who had his attention diverted to the run-up area to his left, did not look right as he approached the parallel taxiway, and he did not see the 172N. The student pilot saw the 172S but thought the other plane would stop. The tower controller was monitoring a different area of the field and did not see the airplanes converging. The student pilot did not take any action to avoid the other airplane and the Cessnas collided.
Probable cause: The failure of the private pilot to see and avoid the student pilot’s airplane, and the failure of the student pilot to avoid the approaching airplane.
For more information: NTSB.gov