This has been much expected since oneworld member LAN (with subsidiaries throughout South America) merged with Brazilian carrier and Star Alliance member TAM. The two airlines have separate corporate entities under the banner LATAM but were going to be forced to make a decision, and all signs have pointed to choosing oneworld over Star Alliance.
That decision is now official.
TAM will leave the Star Alliance in the second quarter of 2014, with an immediate entry into oneworld upon departure from Star.
LAN Colombia — not currently a part of oneworld — will join in the fourth quarter of 2013. That positions oneworld for quite the fight against Star’s AviancaTACA. (Chile’s LAN has been a member of oneworld since 2000 and LAN Argentina, LAN Ecuador and LAN Peru are current affiliate members.)
Oneworld has made some big moves with the addition of Air Berlin and Malaysia Airlines over the past year, and the expected additions of
Qatar and SriLankan in the coming 18 months plus the expected integration of US Airways once it merges with American.
Oneworld is already the strongest alliance for redemptions between the US and South America. This decision both protects and strengthens that position, while Star remains at least marginally stronger from the US to Europe and Asia.
Those American miles and British Airways Avios points just got a little bit more valuable, although I wouldn’t say that United miles got materially less valuable since award space between the US and Brazil on TAM is limited at best and intra-South American award space tends to open up mostly close to departure in my experience.