Historically, the IAM’s seniority integration policy has been to integrate by the current date of hire into the specified classification (dovetailing). However, the IAM recognizes that sometimes issues arise that require more consideration than a simple dovetailing. The IAM will create seniority integration committees made up of representatives from both pre-merger airlines to resolve seniority disputes when they arise. If agreements cannot be reached, the issues will be submitted to a neutral arbitrator for resolution.
The IAM has a history of protecting seniority in mergers - that is not the case for all unions. For example, when United bought Pan Am's Pacific routes in 1985, AFA argued before a neutral arbitrator that Pan Am flight attendants should be stapled to the bottom of the combined seniority list.
In contrast, when US Airways and America West merged, the IAM's merger policy protected the seniority dates of employees at both carriers, even if they were formerly members of another union.