All of this comes after years of conflict between Ryanair staff, The International Transport Workers' Federation (ITF) and the airline's CEO Michael O'Leary.
The disruptions were caused after Irish trade union pilots directly employed by Ryanair voted to go on strike for the first time over a dispute regarding new working practices.
A statement from the airline read: "We have this morning planned to cancel up to 30 of our 290 flights to and from Irish airports on Thursday". 10/1/2012 Ryanair at Dublin Airport.
The strike, which begins at 1am tomorrow, will be the first by Irish-based pilots in the budget airline's history.
Meanwhile cabin crew want better rights to sick pay and the end of steep sales targets that require them to sell perfumes, scratchcards and other items during the flights.
Ryanair offers to meet its pilots (and FORSA) at neutral venue on Tues or Wednesday to avoid unnecessary pilot strike on Thurs (see attached).
"We will do this by cancelling a number of flights on high frequency routes from Ireland to London and other United Kingdom destinations where customers can transfer readily to other flights on Thursday or switch their travel to earlier flights tomorrow (Wednesday) or later on Friday, Saturday or subsequent days".
"All Ireland to Europe flights will operate as normal", it said.
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"It is unacceptable that competitor airline pilots are actively organising strikes by Ryanair's pilots when these airlines will be the direct beneficiaries of any such disruption", it said.
The airline has said only flights between Ireland and the United Kingdom will be affected.
Spanish union Sitcpla representative, Monique Duthiers: "They (Ryanair) are using their transnational nature or the Irish law at (their) convenience".
Ryanair said it had planned for the strike by trying to "minimise the impact" on "families travelling on holidays to Portugal, France, Spain, Italy and Greece".
O'Leary said European air traffic controller are "approaching the point of meltdown".
There have also been strike threats from Spanish ATC staff, which would affect flights between the United Kingdom and holiday spots including Ibiza, Barcelona, Majorca and Menorca.
One begged: "Where can we find exact details on the next week flight plans in and out of Ireland during the strike?"