Travellers planning to use Heathrow Airport may want to leave extra time for their journey if travelling on the service's express trains
Staff who work for Heathrow Express and are members of the Rail Maritime and Transport (RMT) union today began a 48-hour strike.
Action began at 03:40 BST and a further strike is also set to be held on June 24th over pay conditions, which could prompt people to stay in a Heathrow Airport hotel to make their journey easier.
Despite the strike, some rail services will still be available, with trains operating every half hour between the hours of 08:00 BST and 20:00 BST on strike days.
"Our focus is to provide our customers with a regular service to and from the airport during this 48-hour period," managing director of Heathrow Express, Richard Robinson, said.
The company's trains travel to Heathrow Airport from Paddington Station in central London and provide a number of on-board services for passengers, such as Express TV, which shows news and weather.