Originally Posted by flyerCO

1)The DL software only allows the agents to pick airlines that DL has an interline with. 2)There's a business reason for not interlining - It incurs costs to get a bag between airlines, especially if not located in the same area at an airport. Why incur costs to give a benefit to a customer flying an airline that's a competitor? This includes cost if the bag gets lost and never transferred. While the last flown airline will pay the passenger, that airline can then ask for compensation from the airline that never handed the bag off. Also, bags are more likely to be lost when transferring between airlines that aren't partners. A lot of airports use separate baggage systems for different parts of the airport/airlines. Some bigger airports like DXB have one large system used by everyone, but most airports have completely separate baggage systems for each terminal, and in some cases airlines.