The CIS Interstate Aviation Committee has released the final report on the crash of the Polish TU-154. This Russian built aircraft, piloted by Polish Air Force pilots, crashed while attempting to land in poor visibility conditions at Smolensk North Airport in Russia on 10 Apr 2010. The report found that ‘pilot error’ was the cause of this crash, which led to unfortunate loss of the Polish President Lech Kaczynski and several top rung civil and military functionaries.
Invariably crashes, military or civil, find that the pilot error was the cause. Well, if the aircraft is being piloted, naturally then the pilot on control is responsible for the unfolding events. But there needs to be some clarity on this concept of error, particularly in the public mind. This is pertinent since it is vital to understand the dynamics of an accident where trained, experienced, healthy and alert pilot(s) could take erroneous actions leading to loss of aircraft and many a times with tragic loss of life.
Broadly human error, including pilot error, has been defined as “an inappropriate or undesirable human decision or behaviour that reduces, or has the potential for reducing effectiveness, safety or system performance” . An accident is “an unanticipated event, which damages the system and/or the individual or affects the accomplishment of the system mission or the individual’s task” . A large number of accidents occur because of the failings of the personnel directly responsible for the aircraft operations or maintenance or both. Hence, there is need to elaborate upon what are the different types of human error.
Errors . It is a known fact that human beings tend to err. In aviation, errors could lead to inadvertent acts in turn compromising aviation safety with tragic outcomes if not noticed/corrected in time. Errors represent the mental or their intended outcome. There are three basic types of errors: skill-based, decision, and perceptual.
Skill-based Errors. Basic flight skills, once learned, occur without significant conscious thoughts. This skill-based behavior is vulnerable to failures such as the breakdown in visual scan patterns, task fixation, inadvertent activation of controls, and incorrect sequence of steps in a procedure. There are three types of skill-based failures: attention failures, memory failures and technique errors.
Decision Errors. The decision errors represent actions that proceed, as intended yet proves inadequate or inappropriate for the situation. The individual undertakes actions based on incomplete knowledge or makes a poor choice. There are three types of Decision errors: procedural errors, poor choices, and problem solving errors.
Perceptual Errors. Whenever there is degradation of sensory inputs, or inputs are “unusual”, perceptual errors occur. Visual illusions, spatial disorientation or misjudged altitude, attitude, or aircraft speed may precipitate perceptual errors. In such cases, the pilot makes a decision based on faulty information, thus increasing the potential for committing an error. It is important to note that the pilot’s erroneous response to the illusions is the perceptual error and not the illusion or disorientation.
Therefore the errors while piloting an aircraft, in turn, (sometimes) resulting loss of situational awareness of the pilot(s) may cause an accident. However, though not included here, there could also be indirect or latent failures on the part of supervisors and support services, which could contribute or result in an accident. Hence, it is important not to blame it solely on the pilot, when in the complex dynamics of aviation, things if not going as planned, at times lead to an unfortunate accident, with loss of precious lives including the blamed – the pilot(s). More importantly, the onus of preventing future accidents is on the regulators and operators, based on the advise of human factors and aviation safety experts, along with proven technological innovations.
1. Sanders MS, McCormick EJ, eds: Human Error, Accidents, and Safety. In ‘Human factors in engineering and design’. 7th edition, Singapore, McGraw-Hill, Inc. 1992: 656, 662.
2.. Shappell SA, Wiegmann DA. The Human Factors Analysis and Classification System–HFACS. Federal Aviation Administration, Washington, DC, USA; 2000. Report No. DOT/FAA/AM-00/7
Acknowledgement: Image courtesy Wikimedia Commons