According to travel website Skift, the two airlines will be offering support in the coming weeks, though it is unclear if the added functionality will be ready in time for the unveiling of Apple's next-generation iPhone and subsequent iOS 6 debut, both expected to be announced at a special event next week.
An American Airlines representative said the carrier will be ?rolling out an app update in the coming weeks in support of Passbook. In the meantime, customers can still access their mobile boarding passes in the current version of American?s mobile app.?
The publication said Delta is also "actively working" on Passbook functionality, noting the airline's first travel app was released for iOS in 2010.
The news comes on the heels of a report claiming Virgin Australia has unofficially implemented Passbook compatibility. In what is thought to be one of the first instances of a successful airline-supported Passbook transaction, a Virgin Australia flier checked in to and used a boarding pass stored in Passbook to get on a recent flight from Adelaide.
Safari prompt asking to add a Virgin Australia boarding pass to Passbook.
Shaun Lorrain, a frequent flier with Virgin, told AppleInsider that he checked in to his flight through the airline's mobile site on his iOS 6 beta-running iPhone, which recognized that a boarding pass was found and asked if he would like to store it in Passbook. The prompt hints that Virgin is using .pkpass files, an Apple-defined mime type that allows Safari and email clients to recognize boarding passes and send them to Passbook for processing and storage.
"Today after checking in last night and adding it to Passbook, I went straight through Adelaide Security to the lounge," Lorrain said. "Had my breakfast and then proceeded to the gate. They took my iPhone and scanned it the exact same way they would have if I was using the web URL that they text you for a boarding pass."
While Lorrain's experience may not be typical, it illustrates that major air carriers are already preparing Passbook compatibility. United, for example, is the only major airline to officially support Apple's organization app for barcode-based coupons, membership and other digital assets.
Passbook and a host of other new features are scheduled to debut in iOS 6 when the sixth-generation iPhone is announced. Apple on Tuesday sent out invitations to a Sept. 12 special event all but confirming the unveiling of its new handset.