Since November 18, 2010, it has been possible to earn miles in each airline’s program by flying the other carrier on specific routes out of New York JFK and Boston.
Earning in American AAdvantage for flying JetBlue was permitted on:
Earning in JetBlue TrueBlue for flying American was permitted on:
(Of course the Boston transatlantic flights and New York JFK – Tokyo Haneda do not exist any longer.)
But this comes to an end.
American and JetBlue were the subject of merger rumors when American was seeking to chart its own path out of bankruptcy rather than
getting acquired by merging with US Airways.
The explanation offered by American for the termination of this partnership is US Airways’ strength in the Northeast, such as with the US Airways Shuttle between New York LaGuadia, Boston, and Washington National (my only recent JetBlue flight was Washington National – Boston and return, I credited the flights to American because JetBlue hadn’t yet announced their policy of no more expiring points).