What happened
On March 6, 2009, an Air Canada Jazz Bombardier CL-600-2D15, registration C-FDJZ, was conducting a scheduled instrument flight from Vancouver to Whitehorse. During the descent, the aircraft entered a holding pattern due to heavy traffic and winter weather conditions, including snow and low visibility. The captain elected to hand-fly the approach using the Head-Up Guidance System (HGS).
As the aircraft approached Runway 31L, two snow sweeper trucks were operating on the runway surface. The flight crew established visual contact with the vehicles at approximately 300 feet above the runway elevation. Although the first officer noted the presence of the trucks and observed that no landing clearance had been issued, the captain elected to continue the landing, assuming the vehicles would remain clear of the touchdown zone. The aircraft landed approximately 2400 feet past the trucks, clearing them by an estimated 110 feet. No collision occurred, but the aircraft landed without landing clearance.
The investigation
The investigation examined the coordination between Edmonton ACC and Whitehorse Tower, the handover process between the relieved and relieving tower controllers, and the flight crew's performance during the approach. Investigators analyzed the impact of the non-radar environment, where controllers rely on pilot reports to maintain situational awareness. The study also looked into the mental workload of the crew while using the HGS and the effectiveness of the prospective memory tasks required by ATC instructions.
Findings
- Misaligned mental models between the flight crew and the tower controller meant the crew believed the controller knew their exact position, while the controller assumed the aircraft was much further away than it actually was.
- The relieving tower controller did not establish the aircraft's position upon initial contact and relied on a future report that never arrived.
- The first officer experienced task saturation due to high workload, leading to several communication errors, including the failure to report 10 miles final as instructed.
- The instruction to report 10 miles final functioned as a failed prospective memory task, as the crew lacked a specific cue to trigger the report.
- The flight crew failed to request a landing clearance and did not execute a go-around despite observing vehicles on the runway.
- Information regarding the aircraft's holding pattern was not effectively communicated during the controller position transfer.