Human Systems Integration Division @ NASA Ames

Without the intervention of maintenance personnel, equipment used in complex technological systems such as aviation, rail transport, and medicine would inevitably deteriorate to a point where safety and profitability would be threatened. After fuel, maintenance is the largest cost facing airlines (GRA Inc, 2007).

Despite advances such as Built-in Test Equipment (BITE), on-board sensors, and flight data monitoring, maintenance is still a largely human activity. Maintenance technicians work in an environment that is more hazardous than nearly all other jobs in the labor force. The work requires physical strength, dexterity, and balance, but also calls for clerical skills and attention to detail. The work may be carried out at heights, in confined spaces, in numbing cold or sweltering heat). Communication can be difficult due to noise levels and the use of hearing protection. Although maintenance makes an essential contribution to system reliability, improper maintenance can be a major cause of system failure.