The Human Factor: Unstable Personalities

Failure to go around during an unstable approach is the leading factor in approach and landing accidents and is also the primary cause of runway excursions. It is estimated that 97 percent of aircrews that find themselves in an unstable approach condition continue the approach and land. While the study was conducted mostly with professional airline pilots from many different areas of the world, with a median of 10,000 hours total time, I believe the same results would be true for general aviation pilots.

While the Flight Safety Foundation’s project is ongoing, there have already been some interesting results. A major point of the study was to determine the differences, if any, between pilots who tended to go around and pilots who usually continued an unstable approach. As often happens, the researchers found a bell-shaped curve, with 27 percent of the pilots reporting they had done go-arounds in the last five years but had not continued an unstable approach, 52 percent who had flown both unstable approaches and go-arounds and 21 percent who reported flying unstable approaches but no go-arounds.

So it appears that while about a quarter of all pilots are like the individual who wrote to say he can’t remember ever hesitating to go around when his approach was not stable, most pilots are likely to continue some or all unstable approaches in the hopes they can get the airplane back into a stable condition, or at least salvage a passable landing out of the unstable approach. The simple fact is that most of the time we get away with it; otherwise, the accident rate would be astronomical. However, every once in a while someone pushes it a little too far, or is a little too tired, or the conditions are a little worse than predicted, and a runway excursion or crash is the result.

I would fit in the peak of the curve with the majority of pilots. I have written about one experience in which I declared a missed approach just outside the outer marker in a Learjet 55 when I realized we prepared for the wrong approach. However, I also had an unstable approach experience in a Learjet 35. We left early in the morning from Houston Hobby to Washington National (now Reagan National). Our passenger returned early and stated that instead of heading home to Houston, he wanted to fly to Atlanta’s DeKalb Peachtree Airport. When we landed there, he told us he would be back later and left.

We were both asleep when he returned at about 1 a.m., ready to head home. It was my turn to fly, and I was still so groggy that I was barely aware of how we got to Flight Level 410. As we approached Houston at about 4 a.m., we were the only airplane on the approach control frequency, but the controller, who was also probably half-asleep, turned us onto the localizer inside the outer marker. As I was descending rapidly to try to capture the glideslope, I had a growing sense of discomfort in my fatigued brain. I was finally starting to realize I should declare a missed approach when we broke out of the clouds and were able to land visually, but I had taken the unstable approach much further than was prudent or safe.

In my unstable approach experience, fatigue and a desire to just get on the ground, combined with unanticipated and surprisingly poor vectoring by the approach controller, were the major factors. Detailed responses from the pilots who were surveyed by Smith showed that on nine interrelated situational awareness factors, pilots who tended to continue an unstable approach had scores that indicated they had less situational awareness than pilots who tended to go around rather than try to land out of an unstable approach. For example:

• They were less likely to be aware of a gut feeling that the approach was not stable or how to react if they did feel uneasy about the approach.

• They were less able to anticipate risk.

• They had more confidence in their ability to compensate for an unstable approach.

• They were less in agreement with their company’s standard operating procedures, including the criteria for when to execute a go-around.

These situational awareness factors worked together to directly affect a pilot’s perception of and response to risk, with the pilots who tended to continue an unstable approach reporting a much lower assessment of the riskiness and unmanageability of the approach than pilots who tended to go around. These pilots were also more tolerant of deviations from operational limits and procedures, less likely to perform required checklists and calls and less likely to take advantage of other crew members or seek their advice about the best course of action.

The combined effect of these situational awareness factors can lead pilots to adopt a mental model that minimizes the risk of instability and thus reduces their attention to details. Even worse, the pilots who tended to continue an unstable approach were more likely to:

• Feel crew pressure to land and a lack of support for a possible go-around decision.

• Feel uncomfortable when being ­challenged and in challenging others.

• Feel inhibited about calling a go-around due to the authority structure in the cockpit.

• Report less company support for safety.

• Say there was a lower likelihood they would be reprimanded for landing out of an unstable approach.

The ultimate result of all these factors is a normalization of deviance in which a mode of operation outside of company standard operating procedures and federal aviation regulations is either tolerated, passively supported or even approved by pilots, management and sometimes even regulators. Many years ago, the U.S. Navy discovered a similar phenomenon — that squadrons with a high mishap rate developed a culture in which it was acceptable or even expected that pilots would fly more aggressively than Navy flight regulations allowed. Squadrons that emphasized the importance of operating within the boundaries of the regulations often had years of operations with no mishaps, while the squadrons operating with a normalization of deviance experienced one mishap after another.

Smith and his associates developed nine recommendations based on the findings of their research thus far. These include:

• Redefine stable approach criteria and the height below which a go-around is required if the approach is not stable.

• Include a requirement to state/discuss critical instability factors prior to the approach.

• Institute communications (callouts) that are active rather than passive, for example, “stable/unstable” at 500 feet and at stable approach height.

• Develop automated stable approach monitoring and alerting systems.

As is often the case with human factor issues, the most powerful change will result from each pilot honestly assessing his own approach history and tendency to continue an unstable approach rather than going around when unstable below the stable approach height. Pilots and management of multipilot flight operations should honestly assess their organization’s culture to determine if a normalization of deviance has crept into their operation. It is very easy for management to get so focused on the bottom line that they begin reacting negatively to pilots who “waste” time and fuel by doing a go-around. The best way to fight this tendency is to constantly remind ourselves that the cost of one runway excursion accident can exceed the cost of thousands of go-arounds.

People are much more likely to support standard operating procedures they feel they had a part in developing, while procedures and policies that are handed down from management with no employee input are often seen as unrealistic and resented or ignored. In an ideal world, management would include the company’s pilots in a process of seeking weaknesses in their operation and developing specific limits and callouts. While each individual pilot in a large organization can’t have a say in the final decision, each pilot can have an opportunity to voice his concerns and ideas, and management can use that input to come up with the most reasonable and workable solution. As the next step in their research into this subject, the Flight Safety Foundation is assessing the response of flight operation managers to the fact that 97 percent of unstable approaches do not result in a go-around and what role management feels they might play in improving the situation.