Some big issues that would make it hard, but not impossible to do.
Each airline has different versions of the smae aircraft. While not dramatically different, how would you address the training and qualification issue?
Would you separate the pay progression from the seniority list? For example if I was a ex-Pan Am 25 year AMT would I come over at top of scale as a new hire at AA?
Can I bump based on senioirty if I get laid off from one airline to another airline?
Every airline has a different GPM and other internal procedures, how would you address that issue?
I know people with the IBEW and they don't really seem to work for a specific company in as much as they get sent out on jobs. They also have to start over if they change locals.