Passengers returning to Birmingham Airport on Easter Monday suffered delays in landing and others saw departures held up after hydraulic fluid spilled over the runway.
Flights operated by Monarch Airlines, Ryanair, Bmibaby and Flybe were affected and a Lufthansa flight was cancelled.
The problem occurred around lunchtime and led to aircraft circling the airport while the spillage was cleared before landing about two hours late.
One Ryanair flight from Dublin was diverted to East Midlands Airport to refuel before returning to Birmingham.
An airport spokeswoman said up to 1,000 passengers were affected.