Outsourcing aviation maintenance: Human factors implications, specifically for communications

As part of the Federal Aviation Administration's response to the 1997 crash of ValuJet Flight 592, the potential for human errors unique to the aviation third-party repair station environment was investigated. Data collected at 5 U.S. and 1 foreign repair stations disclosed a number of opportunities for errors arising from the more complex interactions among the repair station, the airline customers, and the regulatory authority. Two quantitative studies gathered data to test for 1 expected problem: that of using multiple formats of procedure document. First, a repair station error database was analyzed and concluded that "information" (e.g., documentation) was a significant causal factor associated with specific error types. Second, although repair stations must switch frequently between the documentation systems of different airlines, a task card comprehension study did not find increased error rates from changing document formats. With 54 licensed mechanics, well-designed procedure documentation greatly reduced comprehension errors. Improved documentation by following human factors good practice is recommended as a strategy to mitigate error potential for the repair stations where work is outsourced.