Airlines could be forced to pay compensation to passengers for a delayed flight even if it touches down on time. The top court of the European Union says planes should only be considered to have "arrived" once the door has been opened.

The ruling comes after a passenger sued the budget airline Germanwings for compensation, after his flight landed almost three hours behind schedule.

The European Court of Justice (ECJ) says that although the plane landed within three hours of its scheduled time, the doors were not opened until after the three-hour window and so the passengers on board are entitled to compensation for the delay.

Germanwings said the actual arrival time is the time at which the plane touched down on the tarmac at Cologne/Bonn airport, and that the delay of only two hours and 58 minutes meant no compensation was payable.

The Austrian court before which the case was brought asked the ECJ which time corresponds to the actual arrival time of the aircraft.

In its judgment today, the Court said it "takes the view that the concept of 'actual arrival time' may not be defined on a contractual basis, but must be interpreted in an independent and uniform manner".

The court added that during a flight passengers remain confined in an enclosed space, under the instructions and control of the carrier.

"In such circumstances, passengers are unable to carry on, without interruption, their personal, domestic, social or business activities," the court found.

"Although such inconveniences must be regarded as unavoidable as long as a flight does not exceed the scheduled duration, the same is not true if there is a delay, in view, inter alia, of the fact that the passengers cannot use the 'lost time' to achieve the objectives which led them to choose precisely that flight."

"It follows that the concept of 'actual arrival time' must be understood as the time at which such a situation of constraint comes to an end," the ECJ said.