Main line partners pay for the gas to a contract budgeted amount. If a regional burns more, the regional pays for the rest. This is one reason why contracted flying saves legacy so much money......Its just like paying the electric bill in your house with different level rates.
Sure about that? I have not heard of regional lift paying for their own Jet A in any way shape or form.... My experience is with Delta and ASA so correct me if I am wrong or you have reliable information (does that exist here? )