TAM Linhas Aéreas (São Paulo Congonhas) and US Airways (Phoenix Sky Harbor) have officially left Star Alliance and joined Oneworld with effect from March 31. The transition is the biggest single-day expansion of the oneworld alliance since its launch 15 years ago.

LAN Airlines (Santiago de Chile), TAM's partner in LATAM Airlines Group, has been a full member of oneworld since 2000 with all other LAN passenger airlines - LAN Argentina (Buenos Aires Jorge Newbery), LAN Colombia (Bogotá), LAN Ecuador (Quito International) and LAN Perú (Lima International) - joining the alliance as affiliate members since.

US Airways' regional affiliates, operating as US Airways Express, also transitioned to oneworld, following US Airways' recent merger with American Airlines (AA, Dallas/Fort Worth).

The two carriers will collectively add almost 100 new destinations to the Oneworld network with TAM contributing almost 45 new cities and US Airways adding more than 50.

Oneworld will add another member on May 1 when SriLankan Airlines (UL, Colombo International) joins the fold.