Hundreds of passengers had their flights diverted after the fire brigade was called to a false alarm at Heathrow airport.
An airport spokeswoman said the fire alarm went off at a control tower at the airport, but there was no fire.
Nine flights were diverted from Heathrow to Gatwick while firefighters investigated.
A London Fire Brigade (LFB) spokeswoman said they were called out at 8.41am.
PA