A disagreement between the pilot and co-pilot, an undetected autopilot mode change and a compass error preceded the fatal crash of First Air Flight 6560 in Nunavut, Canada in 2011, according to findings released on 25 March by the Transport Safety Board (TSB).

The incident that killed 12 of the 15 passengers and crew aboard the chartered Boeing 737-200 combi highlights ongoing concerns about effective crew resource management and automation-derived confusion, the TSB report concludes.

The 737-200 collided into a hillside about 1.08nm (2km) east of the Resolute Bay runway while attempting a late go-around on a non-visual approach. A preliminary report issued two years ago concluded that the airport’s instrument landing system was operating normally at the time of the crash.

The final TSB report explains how the crew lined up over a mile east of the Nunavit runway by mistake.

A fatal series of errors began when the pilot turned on final approach about 183m too high, the report says.

An inbound localiser track called for a heading of 347° but the compass error and wind drift pushed the aircraft’s true heading to the right of the runway, and toward a large hill.

Meanwhile, the pilot and first officer were caught in a disagreement. Relying on the aircraft’s GPS track, the first officer advised the pilot repeatedly that they had lined up laterally to the runway and should go-around.

The pilot, however, believed they were following the localiser and a go-around wasn’t necessary. Neither of the pilots realised that the localiser capture had disengaged, as the captain “likely” made a control wheel input that reverted the autopilot to manual and heading hold mode.

At the last moment, the captain commanded a go-around, but it was already too late, according to the TSB report.

The TSB concluded that the first officer was overworked trying to monitor the initial descent rate due to starting the approach too high while struggling to grasp the conflicting navigational cues.

The TSB report suggests that first officer should have over-ruled the captain, but lacked clear guidance from First Air’s procedures.

“In the absence of clear policies and procedures allowing a first officer to escalate from an advisory role to taking control, this first officer likely felt inhibited from doing so,” the report says.

Source: Cirium Dashboard