What happened
On 25 November 1993, a Canadian Forces Canadair CT-1X4 Tutor, operating as Bandit 22 (BDIT22), was conducting an instrument flight rules (IFR) flight from Winnipeg to Sault Ste. Marie, Ontario. During the approach to runway 11, the aircraft was instructed to perform a 360-degree turn to correct its altitude. Simultaneously, an Air Ontario De Havilland DHC-8, registered C-GONX, was positioned on the active runway for departure to Toronto.
As control of the Tutor was transferred from the sector controller to the tower, the tower controller intended to establish radio contact with the military crew to coordinate their arrival around the departing commercial flight. However, the tower controller cleared the De Havilland DHC-8 for takeoff while the aircraft was still on the runway. The controller attempted to reach the crew of BDIT22 via radio but was unsuccessful. Upon realizing the incoming aircraft was on short final and visible on the runway, the controller cancelled the takeoff clearance for C-GONX and ordered the crew to hold their position. The pilot of the Tutor subsequently performed a missed approach.
The investigation
Investigators examined the coordination between the Toronto Area Control Centre and the Sault Ste. Marie Tower. They found that while the weather conditions were above VFR limits, they were below the thresholds required by the existing memorandum of understanding for automatic control transfers.
Technical review of the sequence revealed that the sector controller had delayed instructing the Tutor crew to switch to the tower frequency for over a minute. Furthermore, the investigation looked into the tower controller's operational plan, which relied on the assumption that radio contact would be established at least four miles from the airport to allow for a coordinated arrival and departure.
Findings
- The tower controller placed the De Havilland DHC-8 on the active runway and issued takeoff clearance without first confirming radio contact with the arriving Tutor.
- The sector controller failed to instruct the crew of BDIT22 to switch to the tower frequency in a timely manner, delaying the instruction by more than one minute.
- The tower controller cleared the departing aircraft for takeoff before establishing direct communication with the inbound aircraft.