What happened
On a Saturday at Calgary International Airport, a Cessna 172, registration C-GVLO, was cleared to backtrack on runway 25. The Calgary Tower air controller informed the pilot of the Cessna 172 that he was number one for departure. Simultaneously, an Air Canada Airbus A319, flight ACA185, was holding on runway 16 and was subsequently cleared for take-off.
Without receiving take-off clearance, the pilot of C-GVCO began the take-off roll. Upon hearing the pilot announce he was rolling, the controller instructed the pilot to abort; however, the pilot continued the roll. The controller then had to instruct the Air Canada Airbus A319 to abort its take-off at approximately 120 knots. The large aircraft came to a stop with roughly half of the runway remaining. Emergency Response Services were called to the scene as a precaution against potential brake overheating.
The investigation
The investigation examined the actions of the pilot, the air traffic controller, and the communication procedures in place. The pilot of C-GVLO was a relatively inexperienced private pilot with approximately 75 to 80 hours of flight experience. The controller was experienced, with ten years in the field, but was performing duties that included administrative tasks usually handled by a tower coordinator due to Saturday staffing levels.
Investigators looked into the specific phraseology used during the clearance. The controller had asked the pilot how far back he required for backtracking, and the pilot focused on answering that specific question. Furthermore, the investigation reviewed the controller's use of non-standard phraseology, as he had incorrectly told the pilot he was number one for departure when he was actually second in the sequence.
Findings
- The pilot of C-GVLO initiated the take-off without authorization and without verifying that it was safe to proceed.
- The use of non-standard phraseology by the air controller failed to communicate that the aircraft was actually second in the departure sequence.
- The controller's attention was diverted from runway monitoring to administrative tasks, such as using a computer mouse to record departure times.
- The pilot was experiencing several distractions, including unfamiliarity with the local practice area and the presence of a passenger.
- Training for private pilots at the Calgary Flight Training Centre did not place sufficient emphasis on the radio communication skills and situational awareness required for busy airport environments.