A "Scatter" means that something very serious happened to the program, a fatal error. So it called the recover routine which would save critical data and reboot. After a scatter the controller still had their vital aircraft ID, altitude reporting, and ground speed. When a scatter occurred the scatter horn would go off. It was extremely loud and the sound gave the impression of 1950's cold warish doom. If one happened to be standing by the hardware when a scatter occurred, it would scare the hell out of you. But if you were a programmer you knew that the horm may be sounding because of your own screw up.

A scatter was not the end of the world though. Some ARTCC's and Tracons are combined and since the ARTCC controllers were using long range radars with a scan rate of 12 seconds, a scatter could occur and recover before the radar scan completed a full revolution. Tracons controllers who view a short range radar of 4 or 5 seconds per revolution did notice it but it was not normally a terrible inconvenience even at the busier facilites. It was a very robust system. So this old mainframe which started operation for FAA Air Traffic Control in 1965 still runs in Dayton Ohio, USA until June 2011. Thats the last of the ARTS IIIA. So it ran from around 1965, starting in Atlanta, GA to 2011. That's an impressive record of 46 years. Later I may tell you about the replacement system, but not here.

Continue to ATC Automation part 5

What can automation do for me? Radar Handeoff"
Alone in a sea of non-programmers
Home ATC Automation Part 1 ATC Automation Part 2 ATC Automation Part 3 Scatter Scatter Part 4 Radar Handoff - part 5 The Tower Controller