The Irish Airline Pilots’ Association (Ialpa) will introduce a strict work-to-rule policy starting next Wednesday (26 June) meaning its Aer Lingus pilot members won’t work overtime or beyond their contracted hours, and will reject any requests from Aer Lingus management to change their rosters.

It follows two successful ballots in favour of industrial action over the past week, the latter returning a 99% yes vote on an 89% turnout. Unions are required to give seven days’ notice of any industrial action; Ialpa served Aer Lingus notice on Tuesday (18 June).

The action comes just days before the start of the summer peak season, during which Aer Lingus is expected to carry up to 40,000 passengers a day across its domestic network and routes to Europe, the US and Canada.

It will, though, be limited to pilots employed by Aer Lingus in Ireland. Aer Lingus Regional services, operated by Emerald Airlines, won’t be affected either.

Donal Moriarty, Aer Lingus’s chief corporate affairs officer, said the impact on passengers would be "significant", The Irish Times reports, adding the airline was currently assessing the implications.

Ialpa’s Aer Lingus members are seeking a more than 20% pay increase. The union’s vice-president of finance, Captain Daniel Lanigan, confirmed the notice served on the airline reserved pilots’ right to strike.

Aer Lingus said: "We are currently assessing the impact of the full detail of the industrial action served by Ialpa, including the ’work-to-rule’ they have outlined to commence on 26 June.

"At this time, there is no impact to our schedule. Our customer care team will do all possible to minimise the impact of disruption to our customers. We understand customer concerns."

The carrier said it would keep passengers updated via its website and would alert them directly if their flights have been impacted by the action.

Last week, the president of the Irish Travel Agents Association – Angela Walsh – urged all parties involved to come to a swift resolution to avoid "any disruptive strike action".

"Any pilots strike over the summer months will cause serious impact for both holidaymakers and corporate travellers, as we are in the busiest travel period of the year, with knock on effects on accommodation reservations and connecting travel," said Walsh.

"Travel agents are on the front line when strikes, cancellations and other disruptions occur, and are the first port of call for customers.