British Airways has started to send out emails to customers as a second strike by pilots looks set to affect around 900 flights and 120,000 passengers on September 27.

The move follows an initial 48-hour strike on September 9 and 10 which affected around 200,000 BA passengers and 1,700 flights.

A statement from the carrier said: “To give our customers as much certainty as possible, we are now contacting all those affected to offer them a full refund or a rebook on an alternative date, destination or airline.”

Podcast: BA strikes

British Airways says it is working with “more than 50 airlines to ensure customers have as many alternatives as possible”.

The airline is still urging the pilots’ union Balpa to call off the strike and return to negotiations over a pay deal.

BA said: “We have put forward new ideas through [conciliation service] ACAS this week and have called on Balpa to meet us face-to-face as soon as possible to return to negotiations.

“However, we need to give our customers certainty, so we have contacted all those affected by the union’s strike on September 27.”

Balpa said last night: “We understand that BA has started cancelling its operations on September 27 outside of the 14 day window to avoid having to compensate affected passengers.

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“Balpa set a gap between the first and second periods of strike action to give BA time to work with us to settle this dispute with their pilots.

“We had today been exchanging new ideas to do that via ACAS and so it irresponsible and inconsiderate to its customers that BA has pulled out and decided to start cancelling flights now, just to save money on compensation. BA did not respond to our latest proposals before cancelling these flights.

“Passengers who will be affected by these cancellations should know that we have given BA multiple opportunities to work with us so we could call off this action.”

Adam French, consumer rights expert at Which?, said: “British Airways must now proactively inform those affected by any fresh cancellations of their rights to be re-routed on the next available flight, even if this is with a rival airline.

“Unless a refund is vital to you, don’t be fobbed off by this option. A refund means your travel plans would no longer be the responsibility of the airline and you would not be entitled to any reasonable out of pocket expenses incurred because of the disruption.”

Meanwhile, the Sun claims today that BA pilots are plotting a ten-day “mega strike” in November to “break” the airline, as part of the ongoing pay dispute.

A source is quoted as saying “the disruption seen so far is nothing” and the walkout would bring BA “to its knees”.