Thousands of travellers were delayed from getting away for Christmas due to a power failure at Stansted on Monday.
A satellite building and the transit which takes passengers to the satellite for boarding were hit.
Stansted said neither the main terminal nor the runway were affected and passengers were taken by bus to board flights.
Power was restored after two hours and Stansted reported that flights were operating, but with some delays.
More than 820,000 passengers are forecast to travel through the airport between December 19 and January 2.
A power failure caused by flooding at Gatwick on Christmas Eve last year led to severe delays and a number of flight cancellations.