BREAKDOWNS in the nation's archaic air-traffic-control system are prompting concern throughout the industry as they threaten to delay flights, cost airlines and passengers millions of dollars, and jeopardize safety until a new system comes on line in 1999.
A computer outage at the country's busiest air-traffic-control center in Aurora, Ill., on Tuesday - the fifth at the facility since May - grounded planes across the nation and prevented an automatic alarm from warning controllers of two small aircraft converging near Moline, Ill.
Longer, more frequent breakdowns are anticipated as a dwindling number of government technicians struggle to patch up the fragile, 1960s-vintage air-traffic computers with hard-to-obtain spare parts, the officials and technicians say.
''It's getting really crazy,'' says Wanda Geist, one of 10 technicians who worked all day Tuesday to repair the main, 25-year-old IBM 9020e computer and keep a backup system functioning in Aurora. The center, one of 20 nationwide, governs about 3 million commercial flights a year in a 120,000-square-mile area spanning six Midwestern states.
Air-traffic controllers must rely on obsolete equipment because Federal Aviation Administration (FAA) contractors have fallen years behind in designing the complex computer software needed for a new system. FAA officials say the new equipment will not be installed until 1999, three years later than planned.
Last month, prompted by computer failures, the FAA approved a stopgap measure: a $65 million project to install five temporary replacement computers in the Chicago, New York, Cleveland, Washington, and Dallas centers beginning in October 1997.
The FAA said Tuesday that it aims to accelerate the project, but a spokesman at Loral Federal Systems, the Maryland company supplying the computers, declined to say whether an earlier delivery date was possible.
MEANWHILE, a shrinking force of air-traffic technicians labors to keep the old gear running. Retirements and premature FAA cutbacks in anticipation of the new computers have reduced the number of technicians from 11,000 in 1981 to 6,000, according to Professional Airways Systems Specialists, the Washington-based technicians' union. Air traffic increased 30 percent over the same period.
More than 40 percent of the technicians are eligible to retire, and salary and benefit cuts are encouraging them to do so, says Stephanie Voyda of PASS.
In Aurora, fewer technicians mean a doubled workload for Mrs. Geist and her colleagues. ''We take care of what is immediate, pretty much what is on fire right now,'' she says.
The latest outage began Monday night when technicians switched off the IBM 9020e for maintenance and could not restart it. On Tuesday morning, air-traffic controllers were forced temporarily to use a primitive backup system. They scrambled to clear airspace by ordering a 45-minute nationwide groundstop for flights to or from the region.
The backup system lacks several features including a ''conflict alert'' alarm that would have signalled to controllers that a Beechcraft 400 and ATR 72 had moved within 3.5 miles of each other. A cockpit warning system alerted the ATR pilot, who changed course.
The FAA says it will hire more controllers and technicians to cope with the old computers and backup systems that require more manual labor. ''I don't think we're near a total breakdown. But the computer is harder to service and more likely to break,'' says FAA regional spokesman Don Zochert.