Originally Posted by
Agosti
Someone summarised on the AA forum that if the domestic segment is on JL (e.g. ITM-TYO-JFK), it is usually a valid married segment. If the domestic segment is on the partner (e,g, TYO-JFK-PHL [AA]), it is usually a phantom.
This is not consistent, though. I have seen situations where AA shows phantom availability on an itinerary with a US domestic segment, but the same transpacific segment can be booked through AA or AS with a Japan domestic segment tacked on the other end. Specifically, I recently found a phantom DCA-JFK-HND where JFK-HND-CTS on the same transpacific flight was bookable through AA and AS.
Also, from what I can tell, it's currently impossible to book JL F through AS even if the same flight is available through other partners. At least, no F awards show up on the AS website.