The unfortunate is that this is why the airline union model doesn't really work. What you have are numerous trade unions representing the best interests of their respective groups.

What's needed is one national union for all US airline pilots to be involved in. The union establishes requirements for pilot certification in conjunction with the FAA. Requiring a certain experience level to even be considered for airline employment. As such, the union drives wage negotiations at all unionized airlines to correspond to the minimum rate for any type of aircraft operated in the US 121 fleets. The union also requires seniority to be based on membership in the union.