Aer Lingus and United announced on Tuesday that they will be creating a codeshare partnership starting on November 1, 2008.
This should create additional mileage earning and redemption opportunities for members of both Aer LIngus' Gold Circle Club and United's Mileage Plus frequent flyer programs.
Typically with codeshare partnerships with airlines that are not in the same alliance like in this situation, you are able to earn redeemable miles in the other airlines program (ie. fly Aer Lingus but earn United miles) but you will not earn elite qualifying miles. It is likely that this will be the sort of mileage arrangement between United and Aer Lingus.
There is no doubt that adding additional mileage redemption (and earning) options is a good thing for members of both programs. Hopefully this deal will result in increased traffic for United by becoming a (the?) preferred carrier to provide connecting traffic within the USA for Aer Lingus flyers.
This news also makes me wonder if American's partnership with Aer Lingus is coming to an end. Aer Lingus left the OneWorld alliance on March 31, 2007. According to aa.com's Aer Lingus Partner Page:
Aer Lingus will continue to be an AAdvantage participant airline beyond April 1, 2007. Miles earned, however, are no longer elite qualifying miles.
and
Aer Lingus will continue to be valid on AAdvantage All-Partner awards beyond April 1, 2007.
My bet is that Aer Lingus' partnership with American doesn't last much longer.



