If you want to make a stop on the Frankfurt airport these days, you may experience unpleasant surprises. Already on Monday morning had become known that flights have to be canceled, most of them at Lufthansa. Around 4500 passengers may have wished better to fly from another airport.
During the day still more connections fell out at the largest German airport. By noon, 68 out of some 1400 planned aircraft movements had been canceled. Also for the coming days there is no all-clear. Air travelers must continue to expect breakdowns.
The reason for that is not Lufthansa nor Frankfurt Airport. The cause of the problem is a software glitch at the German Air Traffic Control (DFS). The facility, which is responsible for controlling air traffic in Germany, is based in Langen, about five kilometers from Frankfurt Airport.
In the DFS control centers, around 2000 air traffic controllers guide up to 10,000 flights a day through German airspace. But now the central office had to limit traffic to 75 percent for security reasons. In Munich, Bremen and Karlsruhe, the other DFS bases, everything ran smoothly.
The catchment area of Langen ranges from Lake Constance to Kassel and from the Dutch border to Thuringia. The reason for the problem here might be a February software update. Specifically, it is about the so-called control strip that exists for every flight. These so-called flight progress strips have long been used by air traffic controllers.
Boris Roessler / DPA
On the elongated strip of paper, they have the most important information of a flight assigned to them at hand - including the flight number, type of aircraft, destination, planned arrival time and much more. The pilot can use the small cards to prepare well for an incoming flight and to structure the flights in such a clear way. For this, the control strips of the flights are arranged in a so-called strip pattern.
Touchscreen instead of paper
If the flight then leaves the area of responsibility of a pilot, the control strip is also handed over to the colleague. If he's in another air traffic control center, it's still done by phone or fax. Only recently have digital systems become increasingly popular. Switzerland's air navigation service provider Skygiude introduced an electronic system as early as 2013 and completely dispensed with printed paper.
In the software solution, the control strips can be displayed by touch screen. Exactly this system did not work smoothly in Langen because of the disturbance, therefore the air traffic was restricted by 25 per cent. The air traffic control technicians were working to fix the bug, DFS said. After all: The flight safety is not endangered.
But the bad news: there could be downtime until late Wednesday. The air traffic control has announced that it will not exchange the problematic software until the night of Thursday.