Summary: GAO discussed the Federal Aviation Administration's (FAA) staffing standards for the air traffic controller work force. GAO found that: (1) FAA did not establish a process for maintaining and validating its staffing standards; (2) following the 1981 air traffic controllers' strike, FAA shifted from maintaining a maximum number of controllers during peak hours to providing only minimum staffing levels; (3) because of this shift, FAA underestimated its staffing needs in its 1987 budget request, and had to amend its 1988 budget request; and (4) because of its reduced work force, FAA 1987 overtime expenditures increased dramatically from 1986. GAO also found that: (1) FAA regional and field offices have problems in understanding the methodology for estimating staffing needs; (2) while FAA based its staffing needs on the assumption of 8 shifts per day, field officers used three to five shifts; and (3) of the 15 centers it reviewed, only 1 used current FAA staffing standards. GAO believes that FAA needs to: (1) revise its standards to better reflect the staffing levels managers need to operate their facilities; (2) inform field offices about its staffing process to enhance acceptability; and (3) develop a formal validation process, to ensure that its standards are accurate and current.