The job of air traffic controller is said to be one of the most stressful. This week in the control tower of Pittsburgh International Airport, the stress level reached unhealthy proportions, as the primary radar system failed for the tenth time in the past six months.

The latest radar shutdown, which lasted five hours on Wednesday morning, caused six air traffic controllers to leave work early for stress counseling. It was the week's second radar mishap. On Sunday, March 24, an electrical problem brought the radar system down for three minutes.

In response to the recurring problem, Federal Aviation Administration officials arrived in Pittsburgh on Thursday to begin an investigation of the airport's radar system, the Westinghouse Airport Surveillance Radar 9 system. (Airports in other cities have also experienced malfunctions with the ASR-9.)

The FAA identified one of the reasons for Wednesday's incident as the lack of technicians on duty to check the radar system. To correct this problem, the FAA will increase the number of technicians and their work hours.

Another of the main problems at Greater Pitt is the absence of an adequate back-up power source. Plans to install a new power system by mid-May should help prevent future back-up malfunctions.

Controllers would have certainly welcomed adequate back-up power last Wednesday. At 6:55 a.m., a power surge from a tripped circuit breaker caused the control tower radar screens to go blank. When controllers switched to the secondary radar system, it failed within 30 minutes. Greater Pitt was forced to cede air traffic control responsibilities to the Cleveland Air Route Traffic Control Center in Oberlin, OH. By the time that Greater Pitt's primary radar became operational again at 12:10 p.m., many flights had been delayed and several controllers had succumbed to the stressful morning.

By the end of the week, 10 controllers had requested time off, citing stress related to the recurring radar shutdowns.