Ryanair management and pilots have failed to reach an agreement following three days of talks.
Their negotiations on pay and working conditions lasted more than 12 hours yesterday.
The deadlock follows five days of strike action and now three days of talks.
The discussions are an attempt to resolve issues over pay and working conditions.
Negotiations, which are taking place at Dublin airport, are being mediated by independent troubleshooter Kieran Mulvey.
They were originally scheduled to run for three days from Monday.
Both sides have been asked not to make any public comments while the negotiations are underway.