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Stress, Fear and ‘Startle’

On 20 May 2002, a Boeing B-727 was approaching East Midlands Airport in the UK (Air Accident Investigation Branch (AAIB), 2003; personal communication). Before their departure from Copenhagen, the crew had received the destination weather forecast, which included a warning of thunderstorm activity. The crew joked that English thunderstorms were nothing compared to the weather systems in their native Canada. The flight from Copenhagen was uneventful, but as they approached the airport, they encountered heavy rain and moderate turbulence. Having been vectored clear of weather, the crew began the approach. In order to intercept the localiser, the captain, who was the handling pilot, had to turn through 120°, descend from 3000 to 2000ft and decelerate from 225 tol80 kts. In a descending 30° banked turn, the captain extended the speed brakes. At some point in the manoeuvre, flap 2 was selected, and the stick shaker activated. Initially, this was interpreted as turbulence but, in fact, was an indication of the aircraft approaching the stall. The captain applied go- around thrust. The aircraft pitched to 7° nose down and, having flown through the localiser, was descending fast.

At 800 ft agl, the captain heard the second officer (SO), who occupied the flight engineer’s seat, warning about the speed brakes. By now, the aircraft had accelerated to 235 kts. The speed brakes were stowed, and the aircraft rapidly accelerated further to 250 kts, climbing to 3000 ft before the aircraft was restored to the correct pitch and power. Later, during the investigation, the captain was able to listen to the cockpit voice recording. He was shocked to hear, on the tape, the SO clearly and repeatedly warning of the extended speed brakes from the moment flap 2 was selected. The unexpected severity of the turbulence, the need to execute a complex manoeuvre and the debilitating effects of the rapid onset of stress all played a part in this story.

The personal experience of this captain shows how quickly performance can be impaired. The initial exposure to turbulence was an environmental stressor, and the need to make changes to the planned approach routing represents a plan change, which I will discuss when we look at anxiety. Fatigue was possibly a factor as the crew of the B-727 had flown from Canada to undertake the duty from Copenhagen to the UK. In all probability, they were working off their normal body clock. The rapid, temporary loss of control, together with the captain’s momentary impairment is an example of the fear, or ‘startle’ component of the stress mechanism.

The human ‘startle’ reflex represents an immediate, often instantaneous, reaction to a situation perceived to be highly dangerous or life-threatening. Startle seems to work through two pathways (European Aviation Safety Agency, 2018; Landman et al., 2017). The first, fastest, pathway is mediated by the amygdala is very old in evolutionary terms and is clearly intended to be a defence mechanism. A slower pathway is routed via the neocortex. The amygdala pathway can often be so fast that we are not really aware of the initiating stimulus; our response is akin to a reflex action. The slower pathway allows us to comprehend the problem. Fear and the associated startle can severely inhibit our ability to reason, interpret and resolve problems. This is usually referred to as the amygdala hijack. The Air France flight AF 447 accident over the Atlantic Ocean in 2009 has become the archetypical example of fear resulting in startle in the aviation industry (BEA, 2012). The example of the B-727 given earlier suggests that fear-induced stress triggering is more widespread than might be thought. Here is the experience of the FO on a B-757 attempting an approach into Puerto Plata, in the Dominican Republic, in 1998 (AAIB, 1999):

We had broken off a non-precision approach and instead of going around, the captain called for a visual circuit. Although the cloud-base was down to 800ft agl, I had no reason to doubt that we would make a safe landing. I had flown with the captain before and knew him to be a respected pilot. As we turned finals, it became clear that we were going through the centre-line, and we were now manoeuvring a large aircraft close to the ground. I suddenly realised that my field of view had narrowed to a small area immediately in front of my face. My peripheral vision had gone. If I wanted to see the captain, I had to turn around in my seat and look directly at him. To scan the instruments, I had to move my head from one instrument to another. My head filled with voices that I could not get rid of. I snapped out of it when the GPWS alert went off and the captain decided to go-around.

(Source: personal communication).

Once again, the most obvious effect of the stress mechanism being triggered was the impairment of the senses with the visual field, ironically, narrowing down to better detect danger. Loss of hearing is also a common symptom in acute stress situations, and we saw earlier that the captain of the B-727 did not initially hear his SO. In evolutionary terms, the adaptive advantage of the stress mechanism (increased chance of survival by avoiding harm) has been offset by changes in society.

Current thinking on stress places less emphasis on its function in avoiding immediately life-threatening challenges. It is now more often taken to be a reflection of an individual’s ability to cope with the pressures of everyday life. Specifically, it is the relationship between the perceived demands placed upon us and our perceived ability to cope with those demands. This perspective addresses the problem of more general anxiety rather than fear, and we will come back to anxiety later. First, though, I want to look at fatigue.

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