These are the dreaded words no pilot wants to see engraved on his or her tombstone: “Controlled flight into terrain”.
Yet this is precisely what happened when a 737 was flying into Resolute Bay, Nunavut in August 2011, only to miss the runway on approach and collide with terrain instead, killing 12 of the 15 souls on board.
The reasons are aptly summarized in this brief video from the Transportation Safety Board of Canada.
The sad story of this flight reminds me of something I first learned when I was 17 or so, working on my first ever paying software development contract, for Hungary’s equivalent of TSB Canada. I was taught that it is rare, almost unheard of, for an air accident to have a single cause. Most of the time, accidents happen as a result of a chain of mistakes, and if only one link in the chain is missing, the accident would not occur. In this case, the links of the chain included an inadvertent autopilot setting; a compass alignment issue; bad visibility; and breakdown in communications between the two pilots on board. At any time before the final few seconds, the situation was still salvageable, if only the pilots became aware of what was happening. But by the time the ground proximity warning alarm sounded, it was too late.