TSB has completed this investigation. The report was published on 22 July 2025.
Table of contents
Runway incursion and risk of collision
Airport Terminal Services aircraft tow vehicles ATSTOW504 +1
and
Jazz Aviation LP De Havilland Aircraft of Canada Limited DHC-8-402, C-GGNZ
Calgary International Airport (CYYC), Alberta
The occurrence
Shortly before 1100 Mountain Daylight Time on 06 October 2023, 2 aircraft tow vehicles (tugs) (call sign ATSTOW504 +1) operated by Airport Terminal Services at Calgary International Airport (CYYC), Alberta, planned to drive from Apron 1, to the south side of the airport to reposition an aircraft that was parked on Runway 26. The lead tug driver was given instructions by the ground controller to proceed south on taxiways C, C1, and Y, and hold short of Runway 26. These instructions were amended shortly after with an instruction to enter Taxiway C2 to give way to an aircraft taxiing north, in the opposite direction, on Taxiway C. This communication included an instruction to hold short of Runway 17R, which the lead driver read back.
Once the taxiing aircraft had passed, the ground controller instructed the lead tug driver to continue on Taxiway C and hold short of Runway 26. The lead driver read back the instruction and, at 1104, both vehicles proceeded onto Runway 17R. At that time, another aircraft, a Jazz Aviation LP De Havilland Aircraft of Canada Limited DHC-8-402 operating as flight JZA7124, was beginning its take-off roll on Runway 17R. The aircraft’s flight crew noticed the 2 tugs as the aircraft approached the decision speed (V1), but the flight crew elected to continue the takeoff. When the aircraft became airborne, it was approximately 3700 feet laterally away from the tugs. It then passed overhead the tugs and climbed through 350 feet above ground level as they exited the runway at Taxiway U.
Media materials
Investigation information
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Class of investigation
This is a class 3 investigation. These investigations analyze a small number of safety issues, and may result in recommendations. Class 3 investigations are generally completed within 450 days. For more information, see the Policy on Occurrence Classification.
TSB investigation process
There are 3 phases to a TSB investigation
- Field phase: a team of investigators examines the occurrence site and wreckage, interviews witnesses and collects pertinent information.
- Examination and analysis phase: the TSB reviews pertinent records, tests components of the wreckage in the lab, determines the sequence of events and identifies safety deficiencies. When safety deficiencies are suspected or confirmed, the TSB advises the appropriate authority without waiting until publication of the final report.
- Report phase: a confidential draft report is approved by the Board and sent to persons and corporations who are directly concerned by the report. They then have the opportunity to dispute or correct information they believe to be incorrect. The Board considers all representations before approving the final report, which is subsequently released to the public.
For more information, see our Investigation process page.
The TSB is an independent agency that investigates air, marine, pipeline, and rail transportation occurrences. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.