factor in the near disaster. Other accidents in which pilot fatigue played a significant but officially unacknowledged role include the KLM–Pan American collision in the Canary Islands in March 1977; the Eastern Airlines DC-9 crash in Charlotte, North Carolina, in 1974; and the Pacific Southwest–Cessna collision over San Diego in 1978 (Circadian Information, 2000).
Air traffic controllers obviously have an essential role in maintaining airline safety. Almost all air traffic controllers rotate shifts, and are limited to working 10 consecutive hours or 10 hours during a 24-hour period unless they have been allowed a rest period of at least 8 hours before or at the end of the first 10 hours of duty.22 Air traffic controllers, like pilots, must be given at least 1 day off during each consecutive 7-day period (U.S. Congress Office of Technology Assessment, 1991d).
Many air traffic controllers appear to have a significant sleep deficit (Marcil and Vincent, 2000). The air traffic controllers studied by Rhodes and colleagues (1996) obtained only about 6–6.5 hours sleep on day shifts and only about 5 hours sleep when working on night shifts. And controllers may get even less sleep if their mandated rest period of 8 hours falls at a time when it is difficult to sleep. The accident investigation following the crash of a United Airlines DC-8 freighter into the side of a mountain in Utah at 1:38 a.m. in December 1977 revealed that the air traffic controller, who had omitted a critical radial number when giving holding instructions to the pilot, had had approximately 2 hours of sleep prior to starting his second shift that day at 11 p.m. (he had also worked the 7 a.m. to 3 p.m. shift that day) (Circadian Information, 2000).
No regulations or guidelines limit work hour durations in the aerospace industry. Most employees work a traditional 40-hour week, then dramatically increase their hours in the weeks before a launch or during the mission. Early missions were short, lasting only a few hours or days. Today’s missions, by contrast, may last weeks or even months, placing more demands on mission control staff and astronauts.
Shuttle launches frequently occur at night, requiring flight controllers at Kennedy Space Center to switch from day to night shifts (Kelly et al., 1993). After launch, responsibility for flight operations switches to the Missions Operations Directorate at Johnson Space Center in Houston, Texas, where three flight control teams (FCTs) are used to staff the Missions Operations Directorate for flights of less than 10 days. When flights of 10 days or longer are planned, a fourth FCT is added to allow team members time