Air passengers in Vienna, Austria, may be sleeping tonight on army beds. Vienna Airport said on Sunday it had cancelled or delayed many flights for technical reasons.
There is no indication of a hacker attack.
The issue is transferring flight relevant data amongst Eurocontrol and Austro Control (Austrian air traffic control).
Flights from cities such as Prague and Cologne were delayed on Sunday night as well as departures to destinations such as Tunis, London and Zurich, according to the Vienna Airport website.
Airlines affected included Lufthansa, British Airways, Polish airline LOT, Finnair and Turkish Airlines, Lufthansa, according to the online departure and arrival time tables.
Depending on how quickly the problem was resolved, the airline would try to get as many flights to Vienna as possible.