What happened
In the early morning hours of 29 October 2004, a Britten Norman BN2P Islander, registered as Navair 612, was holding at the threshold of Runway 08R at Vancouver International Airport. While waiting for takeoff clearance, an air traffic controller instructed a de HavHDland DHC-8, operating as Jazz 8191, to taxi to a position on the same runway behind the Islander.
However, the aircraft were not in the sequence the controller believed. While the controller assumed Jazz 8191 was at the runway threshold, the aircraft was actually further down the runway on Taxiway L2. As Navair 612 began its takeoff roll and rotated for lift-off, it passed directly alongside the de Havilland DHC-8, which was entering the runway from the intersection. The crew of Jazz 8191 only realized the danger when they turned to view the threshold and saw the landing lights of the departing Islander. A high-speed collision was narrowly avoided.
The investigation
The investigation examined the controller's situational awareness, the reliability of airport equipment, and the clarity of flight progress strips. It was established that the south tower controller had recently worked a shift where Taxiway L2 was closed, leading to a mental model where the taxiway was assumed to be unavailable.
Investigators found that the controller observed a target on the airport surface detection equipment (ASDE) at Taxiway L2 but dismissed it as a false target due to the system's known history of displaying erroneous information. Furthermore, the flight progress strip for Jazz 8191 contained a displaced and partially obscured taxiway assignment, which caused the controller to miss the "2" in "L2" during a scan of departing aircraft.
Radio communications also played a role. During the period in question, several non-standard radio transmissions regarding navigation lights on other aircraft occurred. One transmission, which referred to "the DHC-8 behind the Islander," inadvertently reinforced the controller's incorrect belief that the aircraft were in the proper sequence.
Findings
- The runway was unsafe for the intended operation because Jazz 8 8191 was taxiing onto the runway in a position ahead of Navair 612.
- The controller failed to verify the ASDE target at Taxiway L2 using binoculars, radio communications, or consultation with the ground controller.
- The controller's reliance on a flawed mental model was compounded by the fact that the taxiway assignment on the flight progress strip was obscured.
- The instruction to Jazz 8191 did not include the specific taxiway intersection, and the crew did not query the missing information.
- Visual limitations caused by darkness and the specific angle of the taxiway prevented both the flight crews and the controller from identifying the true position of the aircraft.