A defect in the radio and telephone system at the German Air Traffic Control Service (DFS) has caused problems to flights over Germany. Several airlines have been affected by delays.
According to the DFS, which operates from Karlsruhe in southern Germany, the entire lower airspace between Osnabrück and Stuttgart was affected on Monday, after lines collapsed at 11:15 a.m. local time (1015 UTC).
Spokeswoman for DFS, Kristina Kelek, said aircraft were only accessible on an emergency frequency, limiting the number of aircraft able to take off and land.
"Therefore we couldn't operate to full capacity," she said. Six flights were diverted as a result of the fault and several others were delayed by up to two hours.
Frankfurt, Stuttgart, Cologne/Bonn, Düsseldorf and Münster-Osnabrück airports were all affected. Airport operator Fraport said that 43 airlines suffered from the defect at Frankfurt International airport alone.
Aircraft on a flight altitude above 7,500 meters were not affected, however. The cause of the failure was not initially clear.
ksb/jm (Reuters, dpa)