So it tranfers legal responsibility for what?
At the larger carriers the union negotiates a contract with the airline. If you receive an offer of employment it will reference the collective bargaining agreement. You agree to bound by the terms of the contract. If there is no union contract there will be (you hope) some sort of employee handbook outlining the T&Cs.
You could say the airlines are in effect an employment agency. At the major airlines in the US there is usually a "holding company." AMR corporation owns American Airlines and American Eagle. They could in theory (and in the case of Eagle may well) move the flying to another airline. There is normally a whole chapter in the contract covering "scope." It will say something like "all flying under the (airline name) will be done by employees covered by this contract." The unions would like to have scope apply to the holding company but there is really no way to do that since you are not an employee of the holding company. AMR could create a whole new company (American Vulture?), move all their RJ flying to Vulture and shutdown Eagle.
Last edited by MarkerInbound; 13th Jul 2013 at 23:43.