Originally Posted by MSPeconomist

I just skimmed through the thread on this on airliners.net. The issue seems to be that DL had asked for more money to renew the interline agreement with AA, at a time when all interline agreements were being renegotiated. In IROPs, the airline in difficulty basically grabs seat inventory on another carrier at the agreed discounted price. Since AA was sending more IROPed passengers to DL than DL was sending to AA, DL wanted AA to pay more for the service. AA refused and hence the interline agreement between DL and AA is ending.

It's generally unfortunate for passengers, but I can understand DL's viewpoint that it shouldn't essentially be subsidizing AA on average in IROPs.