What happened
In the early hours of the morning at Hamilton Airport, Ontario, a Kelowna Flightcraft Air Charter Ltd. Boeing 727-281, registration C-GKFJ, was beginning its departure on Runway 30. At the time, two snow sweepers were performing maintenance work near the end of the runway. During the aircraft's take-off roll, the air traffic controller issued an instruction to abort the take-off. The flight crew initially failed to notice the instruction, and the aircraft continued its roll until reaching approximately 80 knots. Upon noticing the movement, the controller commanded an immediate abort. The crew subsequently rejected the take-off, bringing the aircraft to a stop roughly halfway down the runway, approximately 1200 feet away from the sweepers. There were no injuries and no damage to the aircraft or vehicles.
The investigation
The investigation examined the sequence of communications and the operational environment in the control tower. It was established that the controller was managing both ground and air positions alone due to a colleague being on break. The controller had recently experienced a high workload, managing numerous complex transmissions. The investigation also looked into the controller's recent work schedule, noting a counter-clockwise shift rotation that can contribute to fatigue and sleep deprivation. Furthermore, the investigation reviewed the technical aspects of the electronic flight data system and the use of the blocked-runway indicator, which was active but went unnoticed by the controller during the clearance process.
Findings
Several contributing factors led to the incident:
- The controller failed to notice the blocked-runway indicator on the electronic display, which would have signaled that the runway was occupied.
- A call sign error occurred when the controller initially requested validation for a different flight, creating potential confusion.
- The controller used non-standard phraseology, stating "actually standby" instead of the required "take-off clearance cancelled," which contributed to the ambiguity of the instruction.
- The flight crew's read-back of the take-off clearance occurred while the controller was still holding the push-to-talk button, causing the crew to miss the subsequent instruction to stand by.
- The crew's mental model of an uneventful departure, combined with a brief distraction from a falling chart in the cockpit, meant the abort command went unheeded for nine seconds.
- Scheduling practices involving counter-clockwise rotations and short recovery periods increased the risk of fatigue-related performance decrements.