Pursuant to a congressional request, GAO examined the Federal Aviation Administration's (FAA) training of its aviation safety inspectors, focusing on whether: (1) operations inspectors received the recurrent flight training required to make pilot flight checks; (2) opportunities existed to more efficiently utilize the inspectors; and (3) airworthiness inspectors received the training they needed to perform maintenance inspections. GAO found that: (1) although FAA required that operations inspectors receive flight training every 6 months, 495 of the 786 operations inspectors assigned to flight-check duties had not received the required training; (2) many unqualified inspectors continued to make flight inspections because FAA often waived the training requirement and assigned most of its operations inspectors to flight-check duties, regardless of the number of flight checks that each inspector performed; (3) because some inspectors made only a few flight checks each year, opportunities existed for FAA to assign fewer inspectors to flight-check duties and reduce the number of inspectors requiring training; (4) airworthiness inspectors received only half of the training that FAA had planned for them in 1988 because of the lack of qualified instructors and available courses; and (5) although FAA plans to upgrade and modernize its training system, further improvements are needed to effectively meet the training requirements as the inspector work force grows.