8 flights between Cork and London have been cancelled today.
London's Heathrow, one of the world's busiest airports, has been closed until midnight tonight.
A fire at an electrical substation in west London has caused a "significant power outage".
Cork Airport says anyone flying to London Heathrow today should contact Aer Lingus.
Videos show a huge explosion of fire lighting up the sky and thick black smoke - resulting in 16,000 homes being without power.
Eoghan Corry from Travel Extra says it will impact a number of Irish flights, with around 5,500 passengers affected:
The problem with Heathrow is that it's a very different sort of Airport. Most of the flights are flying to Heathrow to get to somehwhere else. No one else has the capacity to handle that volume of traffic."
