Pilots union Balpa will ballot its Ryanair members on summer strike action.
Balpa is in dispute with the budget carrier over pay and conditions.
The union will issue members a strike ballot on 24 July, closing 7 August.
A positive vote could result in strike action during the peak summer flying season.
Balpa has tabled a detailed pay and conditions claim to try and resolve many outstanding areas of concern for pilots on issues such as pensions; loss of licence insurance; maternity benefits; allowances; and a fair, transparent, and consistent pay structure,” said the union in a statement.
“However, we have not been able to come to an agreement with the company in relation to any one of our concerns.”
General secretary Brian Strutton added: “Our Ryanair representatives have been trying to tackle some of the many issues that result from years of non-recognition of unions within Ryanair. But we have not been able to make any progress with Ryanair at all on any of our areas of concern.”
Ryanair has so far declined to comment.