Rail services to London airports will be subject to disruption due to strike action by members of the RMT on Wednesday 27 July and members of ASLEF on Saturday 30 July.
As different unions are taking strike action, the impact will be different on each day. It is also different from the strike action that took place in June.
Alternative forms of transport will be busy. Advance planning is recommended.
Here is the expected impact of the strikes by London airport:
The Heathrow Express will run a reduced service on Wednesday 27 July.
A half hourly service will operate between 07:30 and 18:30.
From London Paddington trains depart at 10 and 40 minutes past the hour from 07:40 until 18:10.
From Heathrow Terminal 5 trains depart at 27 and 57 minutes past the hour from 07:30 until 17:57.
From Heathrow Central trains depart at 32 and 02 minutes past the hour from 07:35 until 18:02.
On Thursday 28 July, trains will not operate until after 07:10.
No Heathrow Express trains will run at all Saturday 30 July.
The Elizabeth Line will operate a reduced service on Wednesday 27 July on the Western section between Paddington and Heathrow.
Services are not expected to start until after 07:30. Passengers are advised to complete their journeys by 17:30. Services are not expected to start until after 08:00 on Thursday 28 July.
The Elizabeth Line should run as normal between Paddington and Heathrow on Saturday 30 July. The section between Paddington and Abbey Wood will be closed due to engineering work.
The Piccadilly Line should run as normal on both days.
Drop off charges for vehicles at Heathrow terminals will continue to apply. Heathrow is yet to give guidance on inter terminal transfers on strike days.
The Gatwick Express will not run on Wednesday 27 July.
Up to two trains an hour are expected to run from London Victoria to Brighton at 29 and 59 minutes past the hour, stopping at Gatwick.
Up to six trains an hour are also expected to run from London Bridge to Gatwick. Two will run to Gatwick, two will each run to Brighton and Three Bridges, stopping at Gatwick.
These will run after 07:00 and will end before 18:00. A Sunday service is expected to run on Thursday 28 July.
Services are expected to run as normal on Saturday 30 July.
The Docklands Light Railway to London City airport will operate on both strike days.