Australian carrier Qantas will head to the country's Fair Work Commission on Monday to seek arbitration in a pay-related dispute with its pilots at a subsidiary in Western Australia who have voted down a new enterprise deal three times.

Network Aviation, which conducts charter operations for the resources sector, will make an "intractable bargaining application" to the Commission after 18 months of failed negotiations.

Network Aviation pilots are represented by three major workers unions which include the Australian Federation of Airline Pilots (AFAP), the Australian and International Pilots Association (AIPA) and the Transport Workers Union (TWU).

The pilots will strike for 24 hours this week, and the airline's move to seek arbitration comes after they voted down the two most recent proposed agreements despite backing from the unions.

"It is disappointing that as we’ve advised the AFAP of our intention to apply for the Fair Work Commission to assist with arbitration, the union has notified us it plans to take industrial action," a Network Aviation spokesperson told Reuters in an email statement.

About 57% voted down the third proposed agreement, which offered pay increases of more than 25% coupled with new allowances for pilots, Network Aviation said.

The AFAP did not immediately reply to Reuters' request for comments. (Reporting by Rishav Chatterjee in Bengaluru; Editing by Savio D'Souza and Varun H K)