STARTLE RESPONSE IN AVIATION

 

STARTLE- RESPONSE IN AVIATION

STARTLED

It was my third solo in HJT-16 (Kiran) at Air Force Academy (AFA) in the year 1983. Having already messed-up two attempts at landing, I was being talked down by ACP for the third approach. Nervous and tense, I concentrated hard on landing. My gaze got fixated on the aiming point. The runway suddenly expanded wide, filling up the entirety of the wind-screen. I pulled back abruptly to avoid imminent collision with the runway. The airframe pivoted around the center of gravity providing further downward push to the main wheels which impacted hard with the runway. The reactionary force of the impact and the pull on the stick (which created downward negative lift on the tail plane- tilting it down and raising the main wings to strike the air flow at an increased angle of attack thereby increasing the overall upward lift force) bounced the aircraft high up in the air. Stunned for initial few seconds, I regained some sense to realize that both my hands were tightly gripping the stick and pulling it hard into my stomach. I regained some more sense at the apex of the bounce with belated consciousness of the repeated sounds of ‘hold the stick’ from the ACP. Before I could make any sense of the situation, the aircraft got into downward trajectory and landed firmly on the main wheels.  I rolled to the end of runway and cleared for the flight lines. My instinctive act of left hand leaving the throttle and joining the right hand on the stick and pulling it fully back had nothing to do with ACP instructions ‘hold the stick’ as I do not even remember hearing it during the bounce. What was happening to me was that my brain and body were responding to the unexpected and threatening event which had startled me. Startle response is a defense mechanism which developed for our protection as part of the evolutionary process. Our ancestors lived in open jungles where the primary threat to survival was large felines. All cats orient to physical movement, so it made no sense for us to fight or flight, when facing swifter more powerful predators. So, we evolved to freeze first (to avoid being detected), flee (flight) or distance ourselves as a second resort and lastly to fight if there was no other recourse. In analyzing the seriousness of threat, which could be signaled by subtle movements or sounds, their brain would have had two ways to handle it. Either respond immediately to remain away from danger or analyze the situation to see if it is dangerous and thereafter decide the plan of action based on the level of threat. From the evolutionary perspective which dictated survival at any cost the first path was the preferred option which got firmly rooted into our system. Increased startle response is a sign that the nervous system has gone into survival mode.

STARTLE RESPONSE

The Federal Aviation Administration (FAA) Advisory Circular defines startle response as a reaction to an unexpected event that violates a pilot’s expectations and can affect the mental processes used to respond to the event. The initial reflectory part of the ‘startle response’ is called ‘startle reflex’ which is the uncontrollable, autonomic muscle reflex, like fight, flight or freeze and generally lasts for 1-5 seconds. This is followed by a distressing period lasting up-to 20-40 seconds (varying with individuals) where psycho motor functions are impaired. Information processing tasks such as attention perception, Situational Awareness, problem solving and Decision Making are adversely impacted. Communication is often disorganized and incoherent for some time.  Startle can cause distractions and disrupt and erode safety margins. It can also lead to inappropriate intuitive action or hasty decision thus destabilizing the aircraft. Well learned procedures and skills are discarded and are substituted by the first thing that comes to mind. Accident reports show that the startled pilots were not even aware of warning horns and GPWS which were blaring at full blast. The hearing system is the first to get adversely affected during startle.

Coming back to my forgettable third solo. I was already tensed up at the prospect of facing the fury which awaits a trainee who had to be talked down. The calls from SFS and ACP only added to my stress level. I failed to follow correct technique of looking well ahead of the aiming point for round-off. The hard impact and the massive bounce had startled me. The startle reflex, which comes into action instantly without any thought, made me curl up in fetal position. This act of getting into fetal position is also an inbuilt safety mechanism since birth which protects a baby by securing his vital parts and keeping away from the danger. I was overwhelmed by the situation and froze, unable to act. My cognitive as well as psycho-motor functions were paralyzed for almost 10-15 seconds till the aircraft settled down on the runway at taxying speed. During these few seconds I was experiencing ‘cognitive tunneling’ where my vision as well as hearing were adversely affected. There was loss of Situational awareness. All the learned procedures and handling skills had deserted me.  There was no way I would have realized, during that period, what was wrong, what to do and how to come out of the situation. Aviation is inundated with cases where well qualified and experienced pilots failed to react as expected when surprised by critical situations. In some, they had reacted ineffectively or inappropriately or even failed to react in timely manner.

ACCIDENTS DUE TO STARTLE EFFECT

On 25^th Feb 2009 the captain’s radio altimeter in Turkish Airlines Flight 1951, a Boeing 737-800, malfunctioned. It abruptly showed a reading of minus 8 feet during the approach at Amsterdam. This caused the autothrottle to get into ‘retard flare thrust mode’ which, as per fed in logic, reduced power to minimum. As the ILS approach was being made on autopilot, the system ensured that the glide slope was maintained by continuously raising the nose. The speed decayed to the point where the aircraft eventually received a stall warning stick shaker, then stalled, at about 460 feet above the ground. The first officer pushed the throttles forward as the captain took over the controls to recover the aircraft. The situation was still retrievable if the correct actions had been initiated, however the autothrottles, which were still engaged, had retarded the thrust again. The captain did not take any action to reset full thrust for some nine seconds. The aircraft failed to recover and hit the ground. The mishandling and lack of action to apply full thrust were typical of performances impaired by adverse effects on information processing caused through startle.

 Air France Flight 447 (01 Jun2009) – The Airbus A330 was in the cruise over the Atlantic at an altitude of Flight Level 350 (35,000ft) in an area of thunderstorm activity. Following the obstruction of the pitot tubes due to ice crystal ingestion, the autopilot disengaged and the aircraft control systems entered a degraded mode (alternate law). Despite auditory, visual, and tactile indications of a stall situation, the First Officer, who was pilot flying, pulled up and continued to apply full back pressure on the control stick for the remainder of the flight. The aircraft descended rapidly, being held in the fully stalled condition by the First Officer, eventually crashing into the Atlantic Ocean some 3-4 minutes after the initial signs of aerodynamic stall. The correct response to any stall should have been to apply maximum thrust and lower the nose down. The initial response of the First Officer to pull up hard on the control stick was consistent with impaired information processing, decision making and problem solving, typical of a startle reaction. His persistence in maintaining full backward pressure on the stick all the way down was also consistent with either multiple startles or continued degraded information processing following startle. The aircraft crashed into the sea killing all 228 people on board. BEA chief investigator Alain Bouillard equated the reaction of pulling back on the stick to curling instinctively into a fetal position.

 Colgan Air Flight 3407 (12^th Feb 2009) – This Bombardier Dash 8-Q400 was on approach to Buffalo Airport, New York when the captain levelled the aircraft at 2300 feet prior to commencing the ILS approach. Before the aircraft captured the Glideslope and commenced descent the captain lowered the landing gear, lowered partial flaps, and took the Condition Levers to maximum, all the while leaving power close to flight idle. This additional drag rapidly caused the speed to decrease to the point where the aircraft stall warning stick shaker activated. The captain’s response should have been to apply maximum power and to lower the nose to increase speed. The actual reaction from the captain was the opposite: He pulled back on the controls while only applying around 75% of available power. When the stick pusher attempted to push the nose forward, the captain overrode it and continued pulling back. The First Officer also appeared to have raised the flaps to zero during this time, which had the effect of aggravating the stall. The aircraft descended in a fully stalled condition, pitching, and rolling uncontrollably until impacting a house on the ground (NTSB, 2010). It is likely that the captain was initially very startled by the stick shaker and accompanied disengaging of the autopilot. His action to pull back and then continue pulling back against the pressure of the stick pusher were consistent with a severe information processing breakdown. His reactions were contrary to all previous stall training and could well have been induced by physiological effects from the startle reaction. The First Officer also exhibited confusing actions in raising the flaps, which may have been due to startle induced impairment.

West Caribbean Airways Flight 708 (16 Aug 2005), a McDonnell Douglas MD-82, was at FL330 when the captain turned the aircraft’s anti-icing system ON. This reduced the performance of the aircraft. With anti-icing system on, the highest altitude for the aircraft under prevailing WAT conditions would have been lower than the altitude that was being maintained. The captain noticed the loss in power and airspeed but did not realize the source of the problem. The speed dropped close to stall as the aircraft on autopilot kept raising the nose to maintain the height. The aircraft encountered a sudden updraft which led to aircraft entering stall conditions. The captain kept thinking that there was something wrong with both the engines. During the stall the airflow got turbulent behind the wings, interrupting airflow into tail mounted engines, and causing a further drop in the engine output. No effort was made to lower the pitch. Captain made it worse by adding nose up stabilizer trim. The aircraft entered deep stall from where recovery was not possible. Here also the actions of the captain were contrary to the recommended procedures. The loss of power and the subsequent stall startled the captain.

There have been many accidents, including in IAF, attributed to controlled flight into terrain (CFIT.) Many of them had the pilot either not reacting to GPWS or reacting significantly late or lazily. This could have been due to startle effect which impairs psycho motor functions.  

HANDLING STARTLE EVENTS

Aviation frequently throws up emergencies and abnormal situations. Many situations are readily managed by crew who are trained to tackle them. Sometimes, though, the situation could be extremely serious and highly time critical with no prescribed procedures to tackle them. Some events could be so novel and unanticipated that no procedure has been developed. Threatening situations which are also not clearly understood would startle most, though in varying intensity depending on individual’s resilience to startle. Startle symptoms like freezing or curling up should be seen as a non-verbal clue of high psychological distress. It is the body shouting, “I NEED HELP” “I AM IN TROUBLE,” “THINGS ARE BAD AND BEYOND ME.” The other person witnessing these symptoms should view it as a call for help, comfort, and assistance. Like disorientation, startle effects all pilots regardless of age experience or status. It is part of human DNA and it is not easy to unlearn natural human instincts.  The first step to build resilience towards startling effect is to educate the pilots about its effect, symptoms and how to recognize its onset.

The next step is to accept the occurrence of the startle. It is far more common than have been accepted or reported. It is still considered an undesirable and shameful that makes the crew hesitant in reporting such cases. Honestly reporting all occurrences will help in better tackling strategies for such events. With the data base aviators would be forearmed and the stigma and shame attached to it will diminish. Yet another factor we can keep in mind is that getting startled indicates a hyper activated nervous system. Any activity that helps us to relax like Yoga, breathing, mindful techniques, and mental visualization would help in developing startle resilience. Pilot community may be encouraged to adapt some of these activities.

By far the most powerful defense against startle effect is the co-pilot, as startle reflex is unlikely to affect both pilots simultaneously. Anytime the startle symptoms are manifested the other crew must take over the control and get the aircraft into level attitude. This action is important as the logical brain gets overridden in a startled person and he acts instinctively without any thought or logic. This may lead to upsetting the aircraft to an extent from where recovery may be impossible. The startle effect is temporary and, in most cases, the startled pilot becomes functional within 30 seconds after which he could be handed over control following a short debrief of the situation. Adequate training to recognize the symptoms of startle and role of pilot monitoring need to be clearly emphasized in training and operating procedures. It is to be buttressed that the primary duty of copilot is to take over controls in case the pilot is incapacitated and a startled pilot is a pilot who has been rendered incapacitated.