De-icing and Latent Organisational Factors (OGHFA SE)
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|Content source:||Flight Safety Foundation|
|Human Factors Aspects||Stress, Safety Culture|
|Flight Phase||Take Off|
|Operator's Guide to Human Factors in Aviation|
|De-icing and Latent Organisational Factors|
The Accident as a Situational Example
Weather conditions were bad and forecast to deteriorate below minimum landing conditions. This led the crew to select alternate landing sites and load additional reserve fuel. Furthermore, it was the start of the spring school holidays; the flight was full, and a refuelling stop was required on the way back from the first leg of the flight.
When the captain took over the airplane at the departure airport, the auxiliary power unit (APU) had been out of service for five days. This meant that a ground power source was needed to start the engines before departure and that one engine had to be kept running during the stopover because there was no ground power unit available there. De-icing was prohibited by company regulations when one engine was running.
After de-icing, the first flight started the day’s rotation with a 13-minute delay. The decision to leave had been taken because an improvement in the weather was forecast. Finally, the flight arrived at the second airport 20 minutes late. There was a conflict between the captain and the local manager over excess weight due to 10 extra passengers to be boarded.
What is your attitude toward this additional constraint?
The resulting consequence is the need to unload fuel to avoid exceeding the maximum take-off weight (MTOW). This created additional delays, and the cabin crew informed the captain and the first officer of numerous concerns expressed by the passengers about their connecting flights at the final destination. The pilots clearly expressed their frustration. The airplane landed at the return-leg airport with an hour’s delay in snow showers. Passengers were disembarking and boarding while the airplane was being refuelled with one engine running. The fire service was not there.
Do you continue the refuelling?
Fire equipment arrived after the start of refuelling, which did not please the captain, who was well known for his caution and respect for standard operating procedures (SOPs). As refuelling continued, the captain had what witnesses inside the terminal described as an “animated” telephone conversation with airline dispatchers about the weather conditions, the number of passengers and alternate airports. He then returned to the airplane increasingly irritated and showing clear signs of frustration.
Back on board, without any external preflight inspection, the captain asked the ramp agent if de-icing equipment was available. He was told that the airplane could be de-iced before departure.
Would you proceed with de-icing?
The captain did not formally request de-icing, and the ground agent did not insist on it. The airplane left the apron and taxied to the runway covered with 0.50 in (1.27 cm) of wet snow. An additional delay occurred due to priority given to a landing airplane.
More than 70 minutes late, the airplane started to roll on a contaminated runway with the front half of the wings covered with ice, as noted by passengers and cabin crew.
After a longer than usual roll, the captain, the pilot flying, initiated rotation. After some slight buffeting, the airplane touched back down on the runway. Less than 325 ft (99 m) from the end of the runway, the captain initiated a second rotation. The airplane crossed the threshold at about 15 ft, struck treetops and crashed 2,950 ft (899 m) past the threshold and started burning. Many passengers and several crewmembers, including the captain and first officer were killed.
Data, Discussion and Human Factors
The official investigation report emphasized a double message: Nothing can replace a good flight crew, but even the best trained and competent crew cannot compensate for the inherent faults in a complex system such as air transport.
It is clear that the flight crew did not fulfil its role as the last line of defence in the system. But the pilots were not alone in this respect; almost all stakeholders at all levels of the system, through their actions or lack of action, contributed to denying the crew the means to mitigate the consequences of its own actions.
De-icing was not requested. This was the biggest risk taken by the crew. The captain was known for his caution and respect for SOPs. He de-iced the airplane prior to taking off at the beginning of the flight leg. He walked to the terminal during refuelling in shirtsleeves in the snow; it was impossible for him not to have noticed the weather conditions. The captain did not deliberately take the wrong decision; the explanation for the mistake is to be found in the overall context and the associated constraints.
- No preflight external inspection was performed. However, the relative usefulness of a walk-around could be challenged in view of the very limited knowledge that the airline’s crews demonstrated in general on the consequences of wing contamination, as reported in the accident report. This was attributed to a lack of both airline training and crew awareness programs.
- An inexperienced dispatcher allowed the airplane to fly with the APU inoperative, knowing there was no ground power equipment at the refuelling site, so that one engine would have had to be kept running, and that company regulations forbade de-icing an airplane with an engine running. This was a serious dilemma for the pilots, and it is presumed that this was the subject of the animated phone conversation that resulted in the captain being so frustrated. This certainly had a significant effect on the pilot’s decision not to de-ice.
- Numerous mistakes were found in the flight log after the accident. It contained a wrong MTOW, wrong fuel data for the alternate airport and a passenger load greater than allowed. It is not known if these discrepancies were discussed during the phone conversation.
- A weather update on icing conditions was issued by the airport when the airplane was on the ground at the previous airport. This update was known to company dispatchers but was not transmitted to the crew. The captain could have chosen not to land at the planned refueling airport had he known of this weather update.
- The ramp agent, after confirming the availability of deicing equipment to the captain, did not go any further. He did not insist on an answer from the captain about deicing nor did he get a definite answer, even though he knew the wings were covered with snow.
- The two cabin crewmembers knew that the wings were covered with ice and snow. They never tried to bring that information to the attention of the flight crew. Company culture was later shown not to encourage cabin crew to discuss operational matters with the flight crew. Furthermore, two pilots among the passengers did not react either. They mentioned later that “professional courtesy” prevented them from making any judgment on the captain’s operational decisions.
From all these events, the following contributing factors can be identified:
- Inadequate communication;
- Ineffective tools and equipment;
- Incorrect procedures and instructions; and,
- Inadequate training.
Individual factors include:
- Erroneous perception;
- Incomplete knowledge; and,
Furthermore, the accident investigation pointed out that inadequate organizational processes and latent organizational faults were the root cause of most of the risky behavior exhibited by the flight crew.
Latent failures: Inadequate organizational processes
Three distinct organizations were found to have “contributed” to the latent organizational faults that led to the accident. The accident investigation identified the operator, the regulatory agency and the operator’s parent company.
The accident-investigation commission found not only that these latent organizational faults generated errors, but also that they created a working environment in which violations would have been unavoidable if employees were to do their jobs. These latent organizational faults included:
- Ambiguous procedures. Flight, maintenance and dispatching procedures were incomplete for flight in cold conditions, takeoffs on contaminated runways and deicing. Most procedures were derived from piston-engine aircraft operations and tacitly accepted by employees.
- Inadequate manuals. The airline did not produce its own flight crew operating manual (FCOM). Some pilots used other airlines’ FCOMs. They were complete, but differences between them could have created confusion. For example, in relation to MTOW, there were no tables in the FCOM for contaminated runways.
- Inadequate training. The commission found that takeoffs on contaminated runways and contaminated wings were interpreted differently by pilots. Crew resource management (CRM) training had not yet been instituted, another significant deficiency in training.
- Crew rostering. Both pilots were very experienced but were new to the type.
- Company culture and a merger. The airline had been acquired by another airline. The two companies were very different, and the merger was difficult. The purchased airline was clearly the loser. The company takeover and a long pilots’ strike were still on employees’ minds. The fact that the captain came from the airline that was bought and the first officer from the purchaser did not promote cooperation between them.
- Company takeovers are usually stressful for employees. In the case of the purchased company, frequent changes in management, poor morale and operational mistakes resulted and affected flight safety.
- Most managers from the purchasing company had run a charter airline in the northern part of the country’s regulated air transport market. The purchased company was a scheduled airline in the southern, nonregulated market.
- The quality and the training of the company’s dispatchers were inadequate because management did not realize their importance. Their performances were significantly degraded under circumstances such as bad weather due to bad planning and organization.
- The new airplane type had recently been introduced. The airplane program manager was not experienced and was overloaded as chief pilot, chief instructor and a line pilot for the airplane, as well as being chief pilot for another airplane type.
- Additionally, the airplane maintenance division was under-staffed, inexperienced and facing a shortage of spare parts due to a management decision to buy the aircraft type fleet without sufficient spares.
- Finally, the company flight safety director resigned the year before because he had not been supported adequately and had no direct access to the chief executive officer. He was later replaced, after another accident.
- The accident report concluded that the airline was not ready to start passenger revenue services with the new type.
The regulatory agency
Deregulation policy during the 1980s had significantly increased workload at the same time staffing was cut to comply with budget measures.
- The regulatory agency should have audited the operator. Part of the audit was done, but all aspects related to line operations were postponed because the operator did not have an approved FCOM. The audit finally took place, but aircraft operations were not audited because the audit manager had no jet experience. The accident commission called that decision “a serious omission” and said that a proper line audit would have uncovered some of the company’s deficiencies before the accident.
- Regulations require the audit report to be published 10 working days after the end of the audit. The operator received the report after the accident, more than five months after the end of the audit.
- The report concluded the audit was “badly organized, incomplete and inefficient.”
The parent company
The parent airline was the majority shareholder in the operator. But the commission found that the parent decided to stay away from any involvement in the subsidiary airline’s operations.
- The great experience the parent company had gained over the years operating jets was not made available to the operator.
- Parent company support was limited to some information on flight safety brochures and on flight data recorder readouts.
- There was no integration of the operator’s flight safety department within the parent company’s flight safety organization.
The accident report said that the captain was entirely responsible for the decision to land and take off at the refueling airport. However, it also said that the entire system contributed to putting him in a situation where he did not have all the information and tools necessary for correct decision making.
Prevention Strategies and Lines of Defense
The most important consequence of the accident and the subsequent investigation was clarifying that air transport should be considered as a whole system. After this accident, the stakeholders in the system were aware that they all contribute to the overall safety of the system.
Finding scapegoats is easy. Trying to prevent a tragedy such as this one, with its 24 victims, is harder and requires deeper analysis. Such an analysis would require:
- A systemic approach; and,
- Looking for the organizational processes generating faults in the overall defenses of the system that can drive qualified, sane and well-intentioned people to make critical mistakes.
From a human factors point of view, several prevention strategies are summarized below:
This situational example describes an accident caused by failure to conduct deicing operations. But contributing factors, as pointed out by the accident investigation commission, include latent organizational failures by the operator, its parent company and the regulatory authority. Understanding the complete picture underlying this accident can help all involved (flight crew, cabin crew, maintenance, training, company management and regulatory bodies) from falling into the same traps.
Among the following key points are:
- The flight crew is the final line of defense.
- Training is paramount.
- Communication is the key.
- Even the best crew cannot overcome latent organizational faults.
- Flight safety must be recognized at all levels.
Associated OGHFA Material
The following briefing notes provide expanded information to complement the above overview:
- Flight Preparation and Conducting Effective Briefings
- Stress and Stress Management
- Company Safety Culture
Additional Reading Material
- Flight Safety Foundation. Approach and Landing Accident Reduction Tool Kit.
- Joint Aviation Authorities. Ground De/Anti-icing of Aeroplanes, 2005.
- International Civil Aviation Organization. Manual of Aircraft Ground Deicing/Anti-icing Operations. Document 9640-AN/940, second edition, 2000.