Pilots at Swiss, a unit of Deutsche Lufthansa, have been working without an accord since April after management rejected a tentative deal from initial talks, the Aeropers union has said.
The union has been polling members on strike action, and has said a walkout could take place from Oct. 17.
Swiss management has offered to take the case to an arbitration panel, while pilots have made a counteroffer.
German pilots at flagship carrier Lufthansa agreed this month not to strike until mid-2023 under an initial wage dispute agreement.
Strikes and staff shortages forced airlines to cancel thousands of flights to avoid hours-long queues at major airports in the first summer following COVID lockdowns, with disruptions set to continue deep into the autumn.
(Reporting by Arnd Wiegmann, writing Michael Shields, editing by Alexandra Hudson)