Aviat S2 N15TA and Cessna 172 - S N698SP accident near Livermore, California

Probable cause

Failure of the pilots of the Pitts airplane to maneuver the airplane as necessary to observe the taxi route and avoid the Cessna airplane ahead. Contributing to the accident was the local controller's failure to provide the required warning of traffic ahead to the pilots of the Pitts airplane when clearing the Pitts to taxi.

NTSB analysis

While taxiing after landing at a controlled airport, a Pitts tailwheel-equipped airplane collided with a Cessna that was standing with its engine operating. Both airplanes were on instructional flights with a flight instructor and a rated pilot who was receiving instruction aboard.

The airport was equipped with two parallel runways, designated as 25L and 25R. Taxiway G was situated at the end of 25L, was oriented perpendicular to the runways, and extended slightly south of 25L where it terminated at a parallel taxiway. The air traffic control tower (ATCT) was staffed by four persons serving three positions. One person was serving as controller in charge (CIC), one person was serving as local controller (LC), and two people were assigned to the ground controller (GC) position. A controller-in-training (CIT) was actively performing the GC duties, and he was being trained by a full performance level controller.

The Cessna landed on 25L and, as instructed by the LC, exited south onto taxiway G, stopped, and called the GC to obtain clearance to taxi; however, the GC did not respond to the taxi request. The Pitts then landed on runway 25R, and the LC instructed the pilots to turn the airplane left onto taxiway G, hold short of 25L, and remain on the LC's frequency, which the pilots of the Pitts did. At that point, the two airplanes were facing in the same direction, separated by runway 25L and at least 300 feet.

About 50 seconds after the Cessna made its taxi request to the GC, the LC cleared the Pitts to cross 25L, and although required to do so, she did not advise the Pitts of the Cessna in its path. The pilots of the Pitts were unaware of the Cessna's presence until the propeller of the Pitts struck the empennage of the Cessna.

The pilots of the Pitts did not see the Cessna due to the limited forward visibility of tailwheel-equipped Pitts, their failure to S-turn while taxiing, and the limited tail-on visibility of the Cessna. Had the pilots of the Pitts performed S-turns while crossing runway 25L, the collision likely would not have occurred. In addition, the pilots of the Pitts had no expectation that the Cessna was in their path because they were operating in the movement area of a controlled airport and had not been warned of the Cessna by the LC.

Text from the NTSB. Open the NTSB docket for WPR14LA025 for the full record.