Holes in the Swiss Cheese

In 1990, James T Reason, a British psychologist, put forward a model of human systems and the means by which these systems could break down, causing an accident. Often referred to as the Swiss cheese accident causation model, Reason explains that in a given human system, aviation related or otherwise, an accident is usually caused, not by one catastrophic failure, but rather by a series of failures within the system itself. Like the holes in Swiss cheese, the flaws in the different levels of the system, by themselves, typically would not lead to an accident. Bring about the circumstances which would allow the holes in a system to align though, and the possibility of an accident occurring greatly increases. Reason defines the four layers which contribute to an accident within a system as being; Organizational influences, unsafe supervision, preconditions for unsafe acts, and the unsafe acts themselves.

Looking at the crash of Colgan Flight 3407 through the perspective of Reasons model, it no longer becomes just a simple case of pilot error, but rather an intricate failure of the entire system itself. In this particular case, there were numerous holes in the cheese which were all contributing causes. Some likely existed for quite some time prior to the accident itself; small insidious flaws which by themselves were not enough to overcome the redundancies of the system, but together, they created an opportunity for an accident to occur.

Shortly after 10:00 pm, the Crew of Colgan 3407, initiated a descent from their cruising altitude of 16'000 feet to their cleared altitude of 11'000. The exact time at which this descent was initiated is unclear as the crew did not call that they were leaving 16'000 feet for 11'000 as would be expected in a multi-crew cockpit, nor did they run through the descent checklist, which under normal circumstances would have been completed prior to descent. At this stage in the flight, Captain Renslow and First Officer Shaw are talking about their past flying experiences. Renslow spoke of an air traffic controller which he dealt with in Texas whose demeanour and sense of humour were in stark contrast to the controllers who worked the more congested, complex airspace of the north east. The conversation that continued as the crew conducted their descent into the Buffalo area was not unlike conversations between crews on any other given flight. It was not so much the conversation itself, but rather the time and place in which that conversation took place that posed a problem.

Many companies have standard operating procedures that prohibit non flight related conversation below 10'000 feet allowing the flight crew to focus their attention on the operation of the aircraft during the periods of time in which their work loads tend to be the highest; during the departure and approach. On the arrival in to the airport area, the In Range or approach checklist, which is completed upon descending through 10'000 feet, typically signals the point at which conversations are put on hold and the crew's collective attention is turned to the business of flying an aircraft. While being a seemingly benign slip in procedure, in continuing their conversation below 10'000 feet, Captain Renslow and First Officer Shaw increased the possibility of becoming distracted during the approach that was to follow. While keeping up a conversation below 10'000 feet was against Colgan's standard operating procedures, and did increase the risk of distraction at a point in the flight where even small distractions could prove deadly, one would be hard pressed to find a pilot who has not experienced a violation of a sterile cockpit below 10'000 feet at some point. Some pilots will politely point at the altimeter, or simply stop talking altogether as the aircraft descends through 10'000 feet, reminding a talkative crew member that it is time to put the conversation away until they are on the ground. Others may allow the conversation to continue unimpeded not wanting to offend, or cut a good story short.

Given the number of times that the crew of Colgan 3407 yawned during the flight to Buffalo, one could quite safely guess that they were, at least to some degree, tired. Both had been up early that morning and due to a cancelled trip had spent the day in the crew room prior to their flight to Buffalo. While to an outsider it may seem as though remaining in a crew room for the better part of the day prior to departing for Buffalo would have allowed both Shaw and Renslow to get some rest in preparation for their flight that evening, Colgan lacked facilities which would have allowed the crew to get a restful sleep, in addition to the fact that sleeping in the crew lounge was prohibited. Shaw had commuted across the country, from Seattle to Newark, the day prior to her getting into the front right seat of flight 3407, which likely would have only added to her fatigue. Add on top of that a departure time of 9:18 in the evening, a point in the day when most peoples bodies and minds begin to spool down for the night, and it becomes easier to imagine how the crew may have been feeling that evening. While the regulations do make it clear that a pilot is responsible for removing themselves from duty if they suspect that fatigue will impair their ability to act as part of the flight crew, the reality is that at some companies calling in tired results not only in annoyed dispatchers, but also in the potential for disciplinary action.

I have experienced times in the past where accepting a flight, or series of flights becomes a call of common sense as much as a call of regulation. On a last minute call out this February past for a flight to Vancouver, our dispatcher asked whether we would be able to take another trip that had come up upon arriving back into Edmonton. With our planned arrival time of 1:30 am back into the city we could have accepted the second trip while still remaining within our 14 hour duty day although after already having been up since 8:00 am the previous day, we would have been fooling only ourselves if we were to believe that fatigue would have not been an issue had we decided to take the second flight. Ultimately we agreed that it only made sense to decline the flight as the only place we would be fit to be heading after arriving home to Edmonton was bed.

In addition to the long day that Shaw had already endured at the time of departure, she was also fighting a head cold which the crew discuss briefly during the descent into the Buffalo area. Much like the case of fatigue, pilots are required to remove themselves from duty if illness will adversely impact their performance while at work. At the time of the Flight 3407 crash, Colgan had a system in place in which it would take a newly hired first officer 9 months to accumulate a sufficient amount of sick time to cover a 4 day trip. The alternative of calling in sick and missing a few days pay, which although would not affect most people adversely, would have a proportionally sizable impact on Shaw's already low salary of $16,200 a year.

Given the details that are emerging in the Colgan Flight 3407 hearings, it would easy to simply shift a good deal of the blame from the pilots to the company itself. While many of the practices at Colgan seem to be unjustifiably flawed, and the pay disproportionally low, if accidents such as these are to be prevented in the future there are many changes that must take place not just in the way we as pilots make decisions or in the way that Colgan is managed, but in the way that the regional airline industry as a whole is operated. Until the time that those changes are made, it will remain the responsibility of the pilots to maintain their discipline in and outside of the cockpit, and when required, stand up for the safety of the crew, the flight and it's passengers, however difficult, financially and professionally that may sometimes be.

Two Perspectives of The Regionals