FAA uses patch to prevent air traffic lockups

The Federal Aviation Administration has developed a software patch it hopes will
prevent a repeat of the August crash of the IBM mainframe at the Boston Air Traffic
Control Center in Nashua, N.H., an FAA official said.

FAA installed a one-letter patch in the software code that provides flight data
information to the IBM 3090 Host used for air traffic control, said an airways facility
manager at the center.

A technical group at FAA’s William J. Hughes Technical Center in Atlantic City,
N.J., determined a bad data interface locked up the Host for 37 minutes on Aug. 19.

The group discovered the software error after reviewing printouts and tapes of the
automated recordings produced when an interruption occurs, the FAA official said.

The group concluded that bad data sent to the Boston center from the Bradley
International Airport Control Tower in Windsor Locks, Conn., caused the host to lock up,
the official said.

FAA has alerted all en route centers of the software problem and of ways to correct it.
The agency installed the software in 1992. The incident was the first time the system had
locked up, the official said.

The computer failure occurred during peak travel time—just before 8 p.m. on a
Wednesday—as controllers were directing 340 aircraft, including commercial carriers.

When the Host locked up, the center switched to the Direct Access Radar Channel, the
backup system that processes display information.

During the lockup, FAA grounded planes at major airports in New England and New York.
Air traffic controllers passed handwritten notes to each other to track aircraft already
in flight and kept planes in a holding pattern until the agency fixed the Host, the FAA
official said.

FAA rebooted the Host and the center returned to normal service at 8:28 p.m., and air
traffic was reinstated at 8:38 p.m. 

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