On 6 October 2023, two airside tugs travelling together at Calgary were given a clearance by the Ground Controller which they wrongly interpreted as including permission to enter an active runway. On seeing vehicles ahead when already at high speed, the Captain of a departing aircraft already at high speed judged that continuing the takeoff was the best option and the tugs were cleared by over 300 feet. The lead driver expected that had he misunderstood the route, the controller would inform him. Driver error was attributed to ‘procedural drift’ and an absence of both recurrent training and effective oversight.