To elaborate… the pilots' union doesn't want the airlines shifting jobs to lower paying affiliate airlines, so their contracts restrict the sorts of planes whic

To elaborate… the pilots' union doesn't want the airlines shifting jobs to lower paying affiliate airlines, so their contracts restrict the sorts of planes which can be used with the affiliates. Covered in wikipedia: https://en.wikipedia.org/wiki/Scope_clause https://en.wikipedia.org/wiki/Scope_clause