Talks to resolve the ongoing dispute at Aer Lingus have gone on beyond their 22nd hour.
The discussions between management and unions at the airline resumed yesterday morning at 11am.
Both sides are trying to find a way to prevent travel chaos at the country's airports tomorrow.
The row centres on the company's decision to impose new work practices tomorrow, as part of a cost cutting plan, and the company's claims that the new measures will proceed with or without union agreement.
SIPTU is balloting its members on industrial action.
Last night, Aer Lingus warned passengers intending to travel tomorrow of potential severe disruption and advised them to log onto the company's website to change their bookings or to apply for a refund.
SIPTU spokesman Padraig Yeates said that the talks would continue as long as progress is being made.