Airline passengers facing long delays should receive the same cash compensation as those whose flights are cancelled, European judges ruled today.
They decreed that a "long" delay was one which delivered travellers to their final destination three hours or more after the scheduled arrival time.
Compensation would then be payable by the airline at the same rates as for cancelled flights - but not if the delay was caused by "extraordinary circumstances".
The ruling in the European Court of Justice in Luxembourg declared: "Passengers on a flight which is cancelled at short notice have a right to compensation, even when they are re-routed by the airline on another flight, if they lose three hours or more in relation to the duration originally planned.
"There is no justification for treating passengers whose flight is delayed any differently when they reach their final destination three hours or more after the scheduled arrival time."
But the judges added: "Such a delay does not give rise to a right to compensation if the airline can prove that the delay was caused by extraordinary circumstances which are beyond its actual control and which could not have been avoided even if all reasonable measures had been taken."
The ruling said that a technical problem in an aircraft could not be regarded as an "extraordinary circumstance", unless the problem stemmed from events which "by their nature or origin are not inherent in the normal exercise of the activity of the air carrier concerned and are beyond its actual control".
The ruling came in a judgment clarifying a five-year-old EU regulation which grants flat-rate compensation for cancelled flights of between 250 euros and 600 euros (£223 to £535).
The judges said that regulation did not expressly provide that passengers whose flights are delayed also have such a right.
They were dealing with cases referred from German and Austrian courts in which passengers claimed compensation after facing delays - but not cancellations - which meant they arrived at their final destinations 25 and 22 hours after the scheduled time.
The national German and Austrian courts will now consider the EU judges' decision.
The ruling said: "The Court of Justice does not decide the dispute itself. It is for the national court or tribunal to dispose of the case in accordance with the Court's decision, which is similarly binding on other national courts or tribunals before which the same issue is raised."