CHICAGO (WLS) --A computer system designed to prevent airplane collisions on the ground at O'Hare was broken down the past days, the ABC7 I-Team has learned.
The equipment that didn't work sounds an alarm if two planes are going to collide on a runway or a taxiway. It is called Airport Surface Detection Equipment, or ASDE.
According to the Federal Aviation Administration, ASDE computers had to be taken offline on Sunday because of a software problem.
Business travel resumed following the President's Day holiday, but in the towers at O'Hare it was anything but business as usual. A screen that gives controllers detailed coverage of aircraft and airport vehicle movements on the ground, hadn't been working since the weekend.
Starting on Sunday and continuing into Tuesday afternoon, controllers had to piece together ground movements without the automation they were accustomed to.
"O'Hare has been a bit of a soap opera. You go back two years when there were big outages, we had complete closings because of air traffic technology. And now we have a new one," said Joe Schwieterman, Ph. D, an aviation analyst at DePaul University
Some Chicago aviation sources say there were numerous delays because controllers were bogged down in data since Sunday. The FAA maintains that O'Hare delays were not caused by computers on the fritz, but because of snowy weather.
On Tuesday, there were more delays and cancellations at O'Hare than anywhere in the nation, according to the FlightAware website.
An animation of an incident at the Charlotte airport shows the equipment in operation, but there has also a problem with false alarms for planes actually not in danger.
"You throw in these technology issues, and particularly false positives are a real problem because you divert the controllers' attention to a problem that doesn't exist and something else gives way. And I think that is where there has been a bit of a saga with this technology - first the false positives, and now it's out. It's just one more headache we really don't need at O'Hare right now," Schwieterman said.
The FAA did not answer questions Tuesday about whether this kind of software problem happened previously. But some controllers said they are concerned as more ground collisions are narrowly avoided at O'Hare with a new runway and new taxiways for pilots and controllers to learn.