Reducing human errors in aircraft maintenance

---

Simple, often procedural mistakes--rather than those concerned with technology--are responsible for many aircraft accidents and incidents. Maintenance human errors are of primary blame in about 6% of fatal accidents and about 15% are of contributory cause. Overall, operations errors are responsible for 70% of fatal accidents, according to John W. Saull of the International Federation of Airworthiness.

The culprit of human error in maintenance (and flight operations) is the non-adherence to established procedures, with contributing factors such as inadequate/imprecise work planning, particularly for unscheduled tasks, he said. Other contributors are inadequate supervision, imprecise shift hand-over procedures, manpower shortages, and operational pressures.

Progress can be made, but the quest for zero fatal accidents will probably never be achieved in any technological industry, particularly transportation.

The UK aerospace industry and its FAA-equivalent Civil Aviation Authority began to take real notice of maintenance human errors after two serious incidents that could have resulted in passenger casualties. The windshield of a BAC 1-11 came out during climb in 1990. In 1995, A B737-400 lost nearly all lubricating oil after blanking covers had not been refitted on both engines.

The direct result of these and other incidents prompted regulatory authorities, operators, and maintenance organizations to put a greater focus on maintenance human errors. Even before the 1995 incident, the International Civil Aviation Organization (ICAO) had amended Annex 13 (Accident Investigation) Standards and Recommended Practices (SARP) to include the investigation of serious incidents as well as accidents. ICAO Annexes provide world standards for all member states. This opened up the possibility of gaining more data and conducting more analysis, although to date member states are not submitting as much data as originally hoped. Without the data, it is difficult to make decisions regarding medium and long-term safety strategies.

Saull said the UK is in the forefront of flight data recording and analysis, due largely to the independent role of the Air Accident Investigation Board and cooperation from regulatory authorities and operators. In many countries, it is clear that political/economic factors have interfered with making the best use of advanced data recorders, hampering accident/incident investigations. There are also operating industry initiatives using Quick Access Recorders, which allow day-to-day monitoring by the Flight Operations Quality Assurance analysis procedure. Some UK operators are making best use of these devices in controlling operational safety.

It is good to have a lot of data, but research into it must be somewhat limited, Saull said; otherwise, it might just confuse the whole issue. Once problem areas have been identified, they need to be addressed in a coordinated and concerted manner. It will be a long road to seeing improvements, but the building blocks are in place.

A very positive development is the commercial aviation industry's conviction that open reporting of maintenance errors is preferable to a closed system. The "no-blame" culture is replacing the "blame-and-train" culture. Boeing has developed an investigation procedure, Maintenance Decision Error Aid, which has been adopted by many of the world's airlines and maintenance organizations.

Maintenance human factors must be adopted in a positive and continuous fashion, such that they are an integral part of everyday thinking rather than being something special.

Information was provided by John W. Saull of the International Federation of Airworthiness.