Despite the talks of single pilot operations increasing in the aviation community and robotics treading into the spaces of baggage handling, the plain fact remains that humans remain pivotal in aviation. It is (human) researchers who perform flight safety operations; aircraft maintenance is done by humans, and so is plenty of work, such as quality assessment and duties of a cabin crew. However, each human being involved in these steps can have their judgment impaired due to a variety of factors. These are collectively known as human factors. We’ll take a few notable cases (alongside drawing parallels with others) and see how these factors can change the shape of aircraft operations, and aviation at large.

Understanding the SHELL model issued by the FAA

The Civil Aviation Safety Authority (CASA) exemplifies the SHELL model popularized by the Federal Aviation Authority (FAA), offering a succinct way of pointing out the human factors in aviation:

• S = software: the procedures, training and other support aspects of tasks or work design.
• H = hardware: the equipment, tools and technology used in work.
• E = environment: the environmental conditions in which work occurs, including the organizational and national cultures influencing interaction.
• L = liveware: the interrelationships between humans at work.

Which are surrounding the main component of:

• L = liveware: the human operating within the system.

Now that we know the basics of the SHELL model pertaining to the topic of “human factors”, let's dive into a few examples of how different human factors in aviation have come into play during some glaring examples from aviation’s history.

The crash of Germanwings Flight 9525

When one of the pilots operating the Germanwings Flight 9525 was found to have intentionally caused the aircraft to crash into the Alps, it sent shock waves into the aviation community. The co-pilot, Andreas Lubitz, locked the cockpit door as the captain of the aircraft had gone outside (possibly to use the lavatory). It was later found that Lubitz was suicidal and had apparently kept this piece of vital information from his employers.

The case opened up a need for not simply a physical evaluation of a crew taking a flight but also their psychological. The UK Civil Aviation Authority now has a word of caution on the psychological tests that need to be performed so as to reduce the mishaps caused by human factors in aviation:

“ When establishing the policy on psychological assessment of flight crews, the operator may refer to recognised industry standards and best practices in the field of pilot selection, aptitude testing and psychological assessment such as:

1) IATA ‘Guidance Material and Best Practices for Pilot Aptitude Testing’;

and

2) national or European standards of ethical codes of conduct when conducting a psychological assessment, such as by national or European associations for (aviation) psychology”

Some of the ways in which aviation laws evolved after the Germanwings Flight 9525 crash include:

• EASA recommended at least two crew in the cockpit after the crash.
• A statement was issued by the European Federation of Psychologists' Associations showing support for psychological testing in the selection of pilots.
• A statement was also issued by the British Psychological Society offering support for psychological testing and monitoring of pilots.

How the failure to remove a tag caused crashes

There is an innocuous tag (also often used as a key ring) that a lot of people might have seen and reads “REMOVE BEFORE FLIGHT.” Not removing this tag can also lead to aviation accidents, as was the case with the crash of an aircraft of Aeroperu Flight 603 and the 1975 Royal Nepal Airlines Pilatus PC-6 Porter crash.

In the first of these mishaps, the failure to remove the tag led to pilots and ATCs having no idea about the true altitude of the aircraft, and the flight plunged into the sea. In the latter of these cases, the pilot forgot to do a walk-around of the aircraft, and the aircraft crashed after takeoff. Both of these examples show how the “H”- the equipment, tools, and technology used in work - in the SHELL model (used in human factors) discussed above can come into the equation and lead to fatal flights.

Compressing the human factors of aviation into a dozen components

The phrase “dirty dozen” is used in the aviation community while talking about human factors. These dirty dozen include factors such as:

• Lack of communication: the deadliest disaster in aviation history, the Tenerife Airport disaster, was caused due to a lack of proper communication between the ATCO and the pilots.
• Fatigue: When the US-Bangla crash took place in Kathmandu in 2018, it was revealed that the pilot was fatigued and tired due to a lack of sleep.
• Lack of awareness: National Airlines Flight 193 sunk twelve feet into water and led to the drawing of three people on board. Investigations later revealed:

"The crew failed to check and utilize all instruments available for altitude awareness, turned off the ground proximity warning system and failed to configure the aircraft properly and in a timely manner for the approach."

The three points we've briefly touched upon aren't exhaustive. We have done an overview of Part One and Part Two of these dirty dozen. These will provide a much better in-depth coverage of all the human factors.

Piecing it all together

Efficient aviation operation remains at the heart of the modern aviation industry. However, lack of knowledge or complacency can lead to fatal accidents, as we have discussed above. This is why "human factors" will forever be central to aviation operations around the world.