Details of the investment were not disclosed but United said its investment could grow over time. Aloha Chief Executive Officer David Banmiller informed Aloha's employees of the deal this morning.

"We are pleased to broaden and deepen our relationship with Aloha, as we celebrate our 60th anniversary of serving Hawaii," said Jake Brace, United's executive vice president and Chief Financial Officer, in a news release.

United will also expand its marketing and operational ties with Aloha. United also will receive a seat on Aloha's board of directors.

The deal represents the latest involving Aloha since it emerged from bankruptcy in February 2006. As part of its reorganization plan, California billionaire Ron Burkle's Yucaipa Co. and former football star Willie Gault invested about $100 million in Aloha.

Aloha and United have been marketing partners since the early 1990s. Frequent flyers in the AlohaPass and United Mileage Plus programs can earn miles and redeem them for travel on either airline.