INTERNATIONAL CONSOLIDATED AIRLINES GROUP, S.A. 
Britain backed a $22 billion expansion of Heathrow in 2016, ending 25 years of indecision. It is due to approve a third runway at Heathrow in the first half of 2018 and the airport's chief executive said he is concerned that any delay would cause it to fall behind its major European rivals.
"The government has said that (the vote) will take place, but of course, you can't predict anything from a political point of view," John Holland-Kaye told Reuters.
"We are now in a competition with our European rivals for who is going to be the winner out of Brexit... Pushing for that vote in the summer is absolutely vital if we're going to keep on track."
Holland-Kaye said that airports in Paris, Frankfurt and Amsterdam are set to overtake Heathrow in the next five years, and that even if the vote was held in the first half of 2018, the proposed third runway would not be in use before 2025.
Heathrow, Europe's busiest airport, said passenger numbers were 78 million in 2017, up 3.1 percent compared to 2016, in its full year results for the year ended Dec 31.
Stansted, Britain's fourth busiest airport, said separately on Thursday it had asked for permission to be able to serve 8 million more passengers a year, as it seeks to expand at a time when Heathrow and the UK's no.2 airport Gatwick are capacity-constrained.
Stansted said it would reach its current cap of 35 million passengers annually by the early 2020s.
Historically focused on short-haul flights to European holiday destinations, Stansted is increasingly competing with Heathrow with services to the U.S. and Middle East due to start later this year.
Heathrow's planned expansion has caused concern from local residents about the environmental impact, while airlines have voiced concern over airport charges.
Willie Walsh, the chief executive of British Airways owner IAG (>> International Consolidated Airlines Group), said on Tuesday that lawmakers should make Heathrow promise not to raise passenger charges before the new runway is approved.
"We're way too early to make any kind of guarantees about aeronautical charges when we haven't even come to a single masterplan yet," Holland-Kaye said.
He said that Heathrow had already agreed to deliver expansion while keeping charges close to current levels, adding that passenger charges fell 2 percent last year.
"We absolutely have to keep Heathrow affordable as we expand. It's in our commercial interest."
(Reporting by Alistair Smout, additional reporting by Sarah Young,; Editing by Paul Sandle and Elaine Hardcastle)
By Alistair Smout
