The two Air Canada pilots in control of the Airbus A320 that crashed in Halifax on Sunday will face investigators asking tough questions. For a start: why was the aircraft well below the proper flightpath when it slammed into the ground hundreds of metres short of the runway's touchdown zone?
Maybe both engines suddenly failed. Maybe the aircraft was out of fuel. Maybe a flock of geese caused the sort of double flame-out that ended with a heroic pilot successfully ditching his Airbus A320 in the 'Miracle on the Hudson' five years ago. Maybe there was a sudden downdraft of the sort associated with summer thunderstorm microbursts.
Mechanical failure, airport systems and weather will be all be exhaustively probed. So, too, will pilot performance.
Maybe the pilots were flying too low, edging down through the murk in bad visibility, hoping to creep below allowable regulatory minimums just enough to see the runway lights and avoid a 'go around' or diversion to another airport.
It's too early to know where the investigation will lead but controlled flight into terrain – CFIT in the jargon of accident investigators – is the most common cause of major accidents among big airlines. It involves pilots flying a perfectly sound aircraft into the ground because they broke the rules or lost spatial awareness – in other words they didn't know where they were, or went where they shouldn't go.
CFIT and landing accidents account for nearly half of all major crashes, according to a Boeing study of commercial jetliner accidents worldwide over the last two decades. And while the term "pilot error" has fallen into disfavour as investigators say their role is to prevent recurrences, rather than assign blame, "controlled flight into terrain" amounts to the same thing.
Canada's last fatal jet crash was a CFIT incident, when First Air pilots attempting to land in bad weather in Resolute, Nunavut, crashed a Boeing 737 into a hillside, killing 12 of the 15 people on board in August 2011.
The Transportation Safety Board investigation into the Air Canada crash will take months, perhaps years, before conclusions are reached and a final report is published.
It will make safety recommendations, not assign blame.
And in the end Canadians will know less about what went on in the cockpit than would be the case in many other countries. Unlike U.S. investigations, where a transcript of the cockpit voice recorder is part of the public record, Canadian pilots have successfully lobbied to keep them secret and only terse summaries are published.
The TSB investigators will pore through the wreckage, interview the pilots, examine Air Canada's cockpit procedures and assess the landing aids at Halifax's Robert L. Stanfield International Airport, all with a view to making flying safe. TSB investigators will determine – from the flight data recorder – the precise course and altitude, how much fuel was on board, and whether the aircraft was properly configured for landing with wheels down and flaps set.
But unless evidence emerges of a severe mechanical fault or some unexpected event like a bird strike – unlikely in a snowstorm – the focus will be on the flight crew and the sometimes subtle pressures that can cloud decision making and are often found in CFIT accidents.
Some are widely known and have candidly clear names.
"Few pilots are immune to the pressure of 'get-there-itis,' the U.S. Federal Aviation Administration notes in its review of Aeronautical Decision-Making.
"Get-there-itis" can result from pilot overconfidence. It can be spurred by fatigue or a desire not to inconvenience passengers or face the real or imagined embarrassment and extra work and time involved in diverting to an airport with safer conditions. It means pressing on into danger when prudence, and regulations, require a safer alternative.
Pressure contributing to "get-there-itis" ranges from subtle and internal to overt.
Perhaps the most glaring case in recent years was the 2010 fatal crash of a Polish Air Force Tu-154 carrying the nation's president and dozens of high-ranking officials and dignitaries to a ceremony at Smolensk. Despite heavy fog and repeated warnings from air traffic controllers, the pilots pressed on, flying lower and lower, perhaps stressed by the dire warning of the Air Force commander who came to the cockpit and warned "He'll go crazy" – an apparent reference to the president's reaction if the VIP flight diverted because of weather. The Polish military pilots flew on, crashing just short of the runway, killing all 96 on board in another CFIT.
TSB investigators will also examine Air Canada's Cockpit Resource Management (CRM) procedures and how the two pilots behaved. They will want to know which pilot was flying, whether the two maintained the required sterile environment – all-business, no chit-chat – during descent and whether they properly alerted each other to signs that things were going wrong.
Junior pilots in poor CRM environments sometimes feel inhibited from speaking up even as they realize that the aircraft is at risk of being mishandled.
In July 2013, an Asiana Airlines Boeing 777 with 307 people on board, including three senior captains, crashed short of the runway in San Francisco in broad daylight. Three passengers died. The much more junior first officer, who apparently noticed the dangerously decaying speed, didn't warn the flying captain in time to make a difference.
Editor's note: An earlier version of this story incorrectly said Canada's most recent fatal jet crash was an Air North, Yukon's Airline, plane in Resolute. In fact, it was a First Air plane that crashed. This digital version has been corrected. The Globe and Mail apologizes to Air North for the error.