Human limitations on Flight Safety

A study by the Harvard School of Public Health[1] involving 3500 pilots, revealed that 12.6 per cent of the study group may have clinical depression, and 4.1 per cent reported having suicidal thoughts two weeks prior to the study.

These figures do not make for good reading and will give frequent flyers a reality check. Pilots are not superhuman. The brighter side is that these conditions are attributed to factors outside the cockpit and there are known medical procedures to manage and treat them.

Clinical depression has known symptoms and is visible, can be noticed by other crew members in time before they get into the cockpit.

However, there exists an invisible hazard, a serious concern for the aviation industry. It is encountered by most pilots who fly long enough in their career and could set in involuntarily during flight. Worse still, it affects normal pilots – even those with plenty of experience – and is mostly discovered after fatal accidents.

Spatial Disorientation

This is the inability of pilots to correctly interpret aircraft attitude, altitude or airspeed in relation to the earth or other points of reference.

In order to appreciate spatial disorientation and its effect on the human body, there is need to understand spatial orientation.

Spatial Orientation

This is the natural ability to maintain body posture or orientation in relation to the surrounding environment; the ability to know when one is sitting, standing, walking, looking up or down, looking left or right.

Spatial orientation is controlled by three systems; visual (eyes), vestibular (balance organs in the ears) and proprioceptive (limbs). When on the ground, a human body coordinates all three with ease. Eyes provide visual reference, canals in the ears are responsible for lateral and vertical direction, pressure on the buttocks is an indicator of sitting while pressure on the feet and ankles is indicative of standing.

The visual system accounts for 80 per cent of spatial orientation while 20 per cent is shared by the other two systems.

Flying over the ocean on a moonless night deprives pilots use of the visual system for orientation. In such instances, and also when visibility is poor during bad weather and low cloud, crew use onboard instruments for navigation.

Pilots must undergo 40 hours of instrument rating training to get them accustomed to utilizing instruments for navigation, without external visual references for guidance.

However, competence and confidence to fly with instrument guidance does not completely eliminate the possibility of spatial disorientation. This is because during instrument flight, pilots do not use vision for external references, yet this is their most important orientation system. Further, the human body is designed to maintain spatial orientation on the ground, not in the cockpit where it is subjected to acceleration and G-forces.

Aircraft accidents are never attributed to a single factor. Investigators consider multiple factors beginning with managerial failure, supervisory failure, factors contributing to the accident, and finally, the actual cause of the accident.

In instances where spatial disorientation is determined to be a contributing factor, the accident is always preceded by a series of errors and omissions, leading to a high work load and stress when pilots are overwhelmed with interpreting aural and visual information, flying the aircraft and coordinating with air traffic control. This places them in a situation conducive to confusion, loss of situational awareness, and ultimately, disorientation.

Using the analogy of a pitch black house where lights go out unexpectedly because of a blown fuse, an individual is bound to get confused if, within a space of 20 seconds, he/she has to;

Attend to wailing toddlers traumatized by sudden darkness in another room;

Answer a call on a cell phone ringing incessantly;

Try and figure out why the lights are out; and

Call for help from other occupants within the building.

When all this happens at the same time, in the absence of vision, panic and confusion are likely to set in. During the process of moving quickly from one room to another, there is a possibility of missing the exit/entry point and colliding with a wall, chair, door, or missing a step. The fact that this individual has occupied the same house for many years might count for nothing during that 20 second period. The suddenly high workload leads to confusion and stress, causing the individual to lose situational awareness and forget existence of known obstacles or dangers, like furniture and stairs.

In such a scenario, the individual’s first priority should be to restore vision before attending to other matters. This should preempt panic, restore awareness, and avert potential accidents.

It is a lot more complicated for cockpit crew travelling at high speed without external visual references, in close proximity to the ground and with loads of information to process within a short time. Pilots may find themselves operating beyond the limits of the normal human orientation systems, and in the process, failing to manage situations.

Spatial disorientation has been determined to be a contributing factor in a number of air crash accidents. The final investigation reports in respect of Kenya Airways flight 507, Ethiopian Airlines flight 409, Flash Airlines flight 604 and Gulf Air flight 072 have the following in common;

Crew deviated from standard operating procedures laid down in the airline operations manuals, leading to a series of errors and omissions.

Control was lost as the aircraft accelerated either just after takeoff, or while executing a “go around” following an aborted landing.

The planes crashed at night, in Instrument Meteorological Conditions with no external visual references available to the crew.

Crew thought the aircraft were climbing and pushed back on the controls to initiate descent.

Crew did not realize how close they were to the ground, despite receiving several aural ground proximity warning alerts.

Inappropriate “nose down” flight control inputs by the crew explains why the planes crashed.

Crew lost situational awareness and did not react appropriately to correct the improper aircraft altitude and attitude.

Crew lost control of the aircraft during intense work load periods.

There was a breakdown of crew resource management as the pilots failed to work and coordinate as a team.

The first officers could have recovered the aircraft if they had asserted their authority and intervened to correct the inappropriate flight control inputs by the pilots in command.

There was no indication of malfunctioning of navigational instruments, and the aircraft could have been saved if the crew had used them for guidance.

All planes were airworthy, and there were no technical defects that could have affected flight safety.

Crew were licensed and rated on aircraft type.

Crew were medically fit to fly, with no known condition that could have affected their ability at the controls.

Investigators concluded that spatial disorientation was a contributing factor in all these accidents.

Investigators recommended improvement in crew resource management training and strict adherence to standard operating procedures.

Be that as it may, frequent flyers need not worry about night flying or pilot limitations, because air travel is still the safest mode of transport, with ever improving statistics.

IATA’s Director General and CEO while speaking at the release of the 2018 airline safety performance report[2] stated;

“Last year some 4.3 billion passengers flew safely on 46.1 million flights. 2018 was not the extraordinary year that 2017 was. However, flying is safe, and the data tell us that it is getting safer. For example, if safety in 2018 had remained at the same level as 2013, there would have been 109 accidents instead of 62; and there would have been 18 fatal accidents, instead of the 11 that actually occurred. Flying continues to be the safest form of long distance travel the world has ever known. Based on the data, on average, a passenger could take a flight every day for 241 years before experiencing an accident with one fatality on board. We remain committed to the goal of having every flight takeoff and land safely.”

Safety is aviation industry’s highest priority and is defined[3] by the International Civil Aviation Organization as,

” The state in which risks associated with aviation activities, related to, or in direct support of the operation of aircraft, are reduced and controlled to an acceptable level”.

Despite improvements in aircraft technology and automation, hazards and risks cannot be completely eliminated because of human limitations and the environment in which aircraft operate-altitude, speed, temperature and weather. Risk is part of every flight, and can only be eliminated if planes never take to the skies.

In order to manage risk, airlines make safety part of their corporate culture by constantly reviewing and updating their operating procedures. Crew resource management, human performance, safety management and upset recovery are an integral part of initial and recurrent training programs. Pilots are evaluated through regular medical tests and simulator training. Such training allows them build and maintain situational awareness. They can question their senior colleagues and take command of the aircraft should they observe incapacitation, inappropriate control inputs, or departure from standard operating procedures. It also prepares them for team work and coordination of tasks in the cockpit.

Voluntary non-punitive reporting programs encourage crew to report accidental errors and omissions during flight. This allows airlines document reported hazards, and take corrective action either through training or reviewing operating procedures.

Aircraft manufacturers increasingly involve human factors and biomechanics experts during the cockpit layout and instrument design phase. As a result, modern cockpits have improved ergonomics, and behavioral data is more accurate, thanks to hi-tech simulation.

Certifying agencies support airlines by sending advisory circulars and guidance material should a need to change training, operating or maintenance procedures arise.

Finally, regulatory agencies are vigilant in their oversight function.

While accidents and incidents may not be completely eliminated, the message to frequent flyers is, the air transport industry constantly identifies hazards, takes corrective action, and maintains risks at acceptable levels. Manufacturers, operators, training organizations and regulators work together to deliver the industry’s highest priority.

The skies are a lot safer today, thanks to lessons learned from past tragedies.

[1] https://dash.harvard.edu/bitstream/handle/1/29739208/5157081.pdf?sequence=1&isAllowed=y

[2] https://www.iata.org/pressroom/pr/Pages/2019-02-21-01.aspx

[3] Annex 19 First Edition (July 2013)