What happened
On 2 February 2019, a Bombardier CRJ-200 operated by SkyWest Airlines was conducting an instrument flight rules (IFR) arrival from Chicago O’Hare International Airport to Montréal/Pierre Elliott Trudeau International Airport. During the final approach to Runway 24L, a convoy of three snow-removal vehicles entered the active runway. The lead vehicle of the group had previously received and acknowledged instructions to remain clear of Runway 24L; however, the lead vehicle and the two subsequent vehicles proceeded onto the runway surface.
As the aircraft crossed the runway threshold and maintained an altitude of only a few hundred feet, the air traffic controller directed the flight crew to abort the approach. The crew executed a successful go-around. After the snow-removal equipment had exited the runway, the aircraft returned to Runway 24L and landed without incident. There were no injuries resulting from the event.
The investigation
Investigators focused on the movement of the snow-removal convoy and the communication between the ground vehicles and air traffic control. The investigation established that while the lead vehicle had received the specific instruction to stay clear of the runway, the convoy ultimately entered the active runway area during the aircraft's approach.