Today is the first day of the two-day walkout by 2,900 British Airways cabin crew members.
The industrial action has been undertaken by Unite in a dispute over low pay.
In a statement last week BA assured passengers that they would reach their destinations despite the strike.
BA has stated that all flights to and from London Gatwick and London City airports will operate as normal.
The majority of flights to and from Heathrow will also be running as normal though a small number will be merged.
This will mean that some passengers will be flying earlier or later than expected.
BA says it has notified affected customers of these changes but passengers are advised to check the website for the most up-to-date status of their flight.