The Taxonomy of Pilot Violation Behaviours

Defining violation behaviour

Since World War One there have been a large number of aviation accidents caused by human factors, which associating with people’ unsafe behaviours as being slips, lapses, mistakes or violations. In order to better interpret the cause of these air disasters, authors later have developed the taxonomy of errors to percept these failures, but in where all errors are normally explained in the condition of pilot intending to follow rules. However, by some chance the outcome of the catastrophe is attributed to the error of individual violation behaviours. “Violation behaviour is characterized by an intention to deviate from regulations, rules or procedures" (as cited in English & Branaghan, 2011, p. 1). The Federal Aviation Administration (FAA) defines the intentional conducts as a deliberate behaviours in which pilots are aware their behaviours against regulations or rules. According to the concept of common law, the violation acts may be seen as criminal acts (English et al, 2011).As the acts of reporting violation behaviour may involve reporters into the disciplinary or legal actions, violations are probably less reported by conventional flight safety management systems. Yet, according to the violation acts that recorded by Line Operation Safety Audits (LOSA), the data shows that “over half of the observed pilot deviations from SOP were violations” (as cited in English et al, 2011, p.2).

The taxonomy of pilot violation behaviour

Through the consideration of pilot's motivation to violate SOP which based on the study of 'the pairwise similiarity of vilotaion reasoning'1and accident reports from the NTSB, English and Branaghan (2011) sub- divided the HFACS (Human Factors Analysis and Classification System) category of violation at the unsafe behaviour level into four taxa:

  1. Improvement: the intention is to improve safety and increase production, a desire to get better job done.
  2. Malevolent: the intention is to give rise to harm or make a decline of production, a desire to cause damage or sabotage.
  3. Indolent: the intention is to improve the operator relaxation, a desire for lethargy.
  4. Hedonic: the intention is to seek operator stimulus (fun) and excitement, a desire for sensation.

These four categories are distributed into two orthogonal dimensions (A flowchart presenting a method for classifying violations is shown as Figure. 1); the violations of improvement and malevolence are shown on an axis that expresses by intending to influence the aircraft safety or the economics of flight, for either positive or negative purpose; although the intentions of indolent and hedonic violations are not going to change the outcome of flight, the operator violating behaviour along a sensation axis, such as lazy to relax (indolent) or feeling for excitement or fun (hedonic), have adversely influence the flight safety, and may eventually lead to air accidents (English et al, 2011).


Figure.1. Flowchart for unsafe acts level violations (English et al, 2011, p.7).(click on the flowchart for larger size)

Improvement violations

Improvement category contains violation is motivated by a desire to increase the aircraft safety and economics of flights, it seems to be good reason for violation, but in many cases pilot’s actions of violating procedures normally lead to compromise the flight safety. In fact there is no perfect SOP (standard operating procedures) which can instruct pilots to deal with all of situations. In the special circumstance, for the safety consideration the violating procedures may be the best approach. “Originating from seagoing tradition, the legal authority to violate regulations when absolutely necessary for safety is explicitly stated in aeronautical regulations worldwide (from guidance in the International Civil Aviation Organization’s Annex 2) ” (English et al, 2011, p.6). However, in many cases, when pilots neglect or change SOPs, the flight safety is reduced. Compare with designers of SOPs, most pilots have less knowledge about all factors related with risks, and have insufficient understanding about the reasons for developing many rules (English et al, 2011).

An example of improvement category from the cases presented is the Northwest Airlink flight 5719

On December 1, 1993, a Jetstream 31 aircraft operated by Express II as Northwest Airlink Flight 5719 crashed into two ridges at a high descending rate about just three miles away from the Hibbing, MN, airport during an unstabilized approach in night instrument meteorological conditions. This accident caused all 16 passengers and 2 pilots on board died. One of contributing to the accident was that the company (Express II Airlines) failed to identify and correct the widespread unapproved practice of high descent rate to minimize time spent in icing condition. In this case, the flight crews broke the SOP for what they though was a “better” method - they descended aircraft at higher rate than normal standard during an instrument approach in icing conditions to reduce the time in icing condition; they though it was safer than descending aircraft at a standard rate which may expose airframe staying longer in icing condition. However, the crew’s improvement violating behaviour eventually led to an accident (English et al, 2011; Wikipedia, 2011).

The image of Jetstream 31 aircraft embedded from

Malevolent violations

The act of malevolent violations is the most extreme behaviour. It may be motivated by the reasons for political gain, or wish of suicide, or unhappy employee’s revenge to the company due to being unfairly treated, etc. A malevolent act may lead to sabotage and self-destruction. Therefore, in aviation the flight crew’s malevolent violation may cause seriously harm to flight safety or reduce the production (English et al, 2011).

The examples of malevolent category from the cases presented are the Egypt Air flight 990 and the case of FedEx flight 705.

Egypt Air flight 990

On October 31, 1999, the Boeing 767 operated by EgyptAir Flight 990 crashed into the Atlantic Ocean, about 97km south of Nantucket Island, Massachusetts. The accident caused 217 people aboard died. The investigation of the accident was conducted by both American National Transportation Safety Board (NTSB) and Egyptian Civil Aviation Authority (ECCA). As the aircraft crashed into international waters, according to the International Civil Aviation Organisation Treaty, the investigation of the accident should be taken by the jurisdiction of the country of registry of the airplane, the Egyptian Civil Aviation Authority (ECAA), but the ECAA had not enough resources to handle the investigation. Eventually, Egyptian government asked the U.S. National Transportation Safety Board (NTSB) to support their investigation, the NTSB took the lead in this investigation, with ECAA participating. As the evidence the NTSB had collected showed that a criminal act occurred in this accident, and that the crash was intentional rather than accidental, the NTSB report eventually determined that the accident was caused by intentional behaviours of the Relief First Officer. “NTSB’s report did not determine a specific reason for the Relief First Officer’s actions; the primary theory is that he committed suicide” (Wikipedia, 2011, paragraph 3). However, ECAA was not satisfied with the NTSB’s report, and gave a very different conclusion of investigation. The ECAA determined that the factor contributing to the crash was by mechanical malfunctions of the airplane’s elevator control system. But the NTSB rejected the conclusion made from ECAA, and concluded that there was no scenario of mechanical failure that either they or the ECAA could match the those recorded by flight data recorder, and that even though the mechanical failure had occurred on the aircraft of flight 990, according to the design of Boeing 767, the aircraft could be able to recover the situation (Wikipedia, 2011)

Video embedded from YouTube on 12Oct2011

FedEx flight 705

On April 7, 1994, FedEx flight 705, a Mcdonnell Douglas DC-10-30 cargo jet experienced an attempted hijacking on the way from Memphis, Tennessee to San Jose, California. The hijacking was staged by a FedEx employee, Auburn Calloway, who is a maintenance engineer at the company. The intention of Calloway’s Hijackers behaviour is to extract revenge on the Federal Express, because he was answer to facing possible dismissal for lying about his former flying experience. On the flight 705, he intended to kill all three crew members by using his two hammers and a spear gun which he carried in a guitar case, and then crashed the airplane into headquarters of Federal Express. In order to make his suicide attack looks like an accident, he tried to interrupt the work of airplane’s cockpit voice recorder before takeoff. If he died in an “accident”, his family would receive a compensation of $2.5 million from his life insurance. Fortunately, Calloway’s plan was aborted. The crews of flight 705 bravely resisted with Calloway’s attack, and successfully restrained him. Although the three flight crew members of flight 705 sustained serious injuries, they showed the great airmanship to recover the aircraft and eventually made a safe landing at Memphis International Airport (Wikipedia, 2011).

Video embedded from YouTube on 12Oct2011

Indolent Violations

Indolence is motivated by the lazy attitude in which people desire to reduce their workload. Rules are neglected because pilots think this is no necessary to pay much effort just for the expected minor safety gain, or probably because of the pilot’s complacency or their professional confidence. Some authors point out that one of common reasons for intended deviations is that pilots think the SOP is too “troublesome”, exactly following the full procedure is only needful for less skilled pilots. As the aircraft’s safety margin is vey high, indolent behaviour is normally connived by feedback which the airplane did not crash. This violating action may be caused by individual fatigue, or may drive by part of a larger culture of noncompliance (English et al, 2011).

The examples of indolent category from the cases presented is the Delta Air Lines Flight 1141

On August 31, 1988. A Boeing 727 operated by Delta Air Lines (Domestic Flight 1141) from Dallas-Fort Worth International Airport to Salt Lake City International Airport, Salt Lake City, Utah with 108 people on board crashed on take-off from Dallas Fort Worth. The accident killed 2 flight crew members and 12 passengers on board, and injury 76 others. There were two main factors contributing to the crash; one factor was that the flight crew never configured the wing’s flaps and slats on the proper position for task off. If wing’s flaps and slats were in a retracted condition, the aircraft could not gain sufficient speed for climb, which caused a loss of lift. Another factor was that the aircraft’s take-off warning horn did not alert the flight crew with this anomaly condition (aircraft was taking off without the wing flaps and slats correctly configured) during the take-off roll (Wikipedia, 2011). The NTSB determined the primarily cause to the crash was inadequate cockpit discipline, such as intentional no-compliance with procedure, and the no-essential conversation between flight crew members (according to the requirement of FAA regulation - Sterile Cockpit, there should be no any conversation that is unrelated with aircraft operation before or during the take off). (English et al, 20011; Wikipeda 2011)

The folowing vedio discloses the crew memebers' conversation from the cockpit voice recorder of Delta Air Lines Flight 1141 on August 31,1988.

Video embedded from YouTube on 12Oct2011

Hedonic violations

The hedonic violations are motivated by seeking for increasing the thrill, fun or excitement. This can be understood as seeking pleasure is the intention of breaking safety rules. Although it seems strange, English (2011) points out that “the behaviour is frequently seen in aviation” (et al, p.8). Some of flight crew probably think that the actions of violating SOP may create risk, it is seen as enjoyable stimulating while not actually leading to a substantial harm to flight safety. Some of authors suggest that “for young male pilots, validation of manhood is a more important psychological requirement than is safety; it has recently been found that benign violations lead to laughter and amusement" (English, 2011, p.8)

The examples of hedonic category from the cases presented is Trans States Airlines Embraer ERJ-145LR, Flight AX5506

On August 14,2008. An Embraer ERJ-145LR operated by Trans States Airlines (Flight AX5506) from Jacksonvill, FL to St. Louis, MO (USA). While the flight en route to the St. Louis airport, the first officer told the captain that his 45 degree flaps landings are a “little bit extreme” continuing, that the landing are a “little non-standard, but it is way more fun”. “the first officer increased the pitch angle starting at 34 feet Angle to a pitch angle of 13 degrees nose up (angle of attack 17 degree)” (Hradecky, 2008,np), the stick shaker warning system had activated for a few seconds before the airplane contacted on the ground, then aircraft ‘s tail section stroked on the runway. Fortunately, 36 people on board were safe, no one were injuries (English et al, 2011; Hradecky, 2008).

The image of Trans States Airlines Embraer ERJ-145LR-N829HK embedded from

The reason to construct violation taxonomy

English and Branaghan (2011) point out that the reason to construct violation taxonomy is not just simply to list the flight crew‘s violation behaviour, it is to create a framework which can facilitate safety management systems to implement intervention and mitigation strategies.


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