The Irish Airline Pilots’ Association (Ialpa) on Tuesday (18 June) served notice on Aer Lingus that it would be instructing its Aer Lingus members to adopt a strict – and "indefinite" – work-to-rule policy from next Wednesday (26 June).

This means they will refuse to work overtime or work beyond their contract hours, and reject any management requests to change their rosters.

It follows two votes in the space of a week in favour of action up and including a full strike in an ongoing dispute over pay. Talks have broken down with Ialpa seeking a more than 20% pay rise for its members.

Aer Lingus on Thursday (20 June) confirmed it would cancel between 10% and 20% of its flights during the first five days of the action by Ialpa’s Aer Lingus members.

The airline said the move would allow it to protect as many services as possible for as many of its customers as possible. It will start communicating any planned cancellations in the coming days both to affected customers and travel agents.

Ialpa’s action comes days before the start of the summer peak season, during which Aer Lingus is expected to carry up to 40,000 passengers a day.

The action will, though, be limited to pilots employed by Aer Lingus in Ireland. It won’t extend to Aer Lingus Regional services between the UK and Ireland operated by Emerald Airlines, and won’t affect Aer Lingus’s transatlantic schedule out of Manchester to New York and Orlando, which is operated by Aer Lingus UK.

Aer Lingus has described the action as "wholly unnecessary" while Irish taoiseach Simon Harris said both sides involved in the dispute needed to "step back from the brink".

Passengers with flights booked between 26 June and 2 July can change their flights for free, request a refund voucher for the full value of their flight, or request a cash refund for the full value of their flights.