On 31 December 2010, an Embraer ERJ190 being operated by Air Canada on a scheduled passenger service from Denver to Chicago was about to begin the take off roll from the full length of runway 34R at Denver in normal day visibility in accordance with ATC clearance when the flight crew observed the headlights of a vehicle approaching along the runway towards their position. The aircraft held position and advised ATC who had previously been unaware of the presence of the vehicle.
An Investigation was carried out by the National Transportation Safety Board (USA) (NTSB). It was established that the vehicle observed had been a Denver Airport Operations Vehicle being driven by the Aviation Operations Manager as the lead vehicle for the snow removal vehicle team. His vehicle had been authorised by TWR personnel to proceed southbound on taxiway F, which parallels runway 34R to the east of the runway, in preparation for snow removal operations on that runway. The runway had been mis-identified as taxiway F and entered at taxiway WC, about 1200 metres from the aircraft.
Once TWR had been advised of a vehicle on the runway, they contacted the lead vehicle of the snow removal team to advise him that a vehicle was on the runway without realising that this was the vehicle involved. The driver had failed to realise that his was the vehicle on the runway and had initially attempted to visually identify the vehicle on runway before eventually realising that his vehicle was the vehicle in question.
KDEN airport diagram - click to enlarge
The Investigation noted that TWR ATC was equipped with an Airport Surface Detection Equipment, Model X (ASDE-X) system which was supposed to aid the identification and de-confliction of aircraft and vehicles on the airport to assist ATCO situational awareness and to prevent runway incursions. However, the ASDE-X system was set to prevent nuisance alerts for aircraft and / or vehicles travelling at less than approximately 40 knots, so did not provide an alert.
It was noted that TWR manning for arrivals and departures on runways 34L and 34R at the time of the incident was an instructor controller and a trainee controller. Both these controllers stated to the Investigation that “the runway appeared to be clear prior to issuing a takeoff clearance to (the ERJ 190)” and the trainee said that he had “scanned the runway and the ASDE-X display in the tower and everything appeared clear”.
The Probable Cause of the incident was determined as:
- The driver of the operation vehicle's misidentification of the runway for an adjacent taxiway, resulting in a runway incursion with an aircraft in position for takeoff.
The Final Report of the Investigation OPS11IA273 was approved on 3 October 2011. No Safety Recommendations were made.