A strike by train drivers is crippling London transit and causing delays for travelers headed for the airports. The strike began Jan 30 and may intermittently re-occur through March, according to Travel Research Online.

Members of the ASLEF union are on strike against the Southeastern, Southern/Gatwick Express, Thameslink, South Western Railway and Great Northern railroad lines over the week of January 30 through Monday, February 5.

The union will hold two more 48-hour strikes on the London Overground, on February 19 and March 4. And on the London Underground, the Central Line is suspended between North Acton and Ealing Broadway due to a “points failure.”

The strikes are causing widespread delays for travelers trying to get to and from London airports. London Heathrow is accessible on the Heathrow Express, the Elizabeth Line, and the Tube. But other major airports will be badly affected—with most trains canceled on strike days.