The union that represents ramp workers at United Airlines won an election on Thursday to cover more than 14,000 workers as it combines with Continental.

It's a big win for the International Association of Machinists and Aerospace Workers, which just gained more than 7,300 Continental workers from the International Brotherhood of Teamsters.

In June the IAM lost 9,300 Continental flight attendants to the Association of Flight Attendants-CWA. Last year it lost votes to hang onto ramp workers, ticket agents and other ground workers at Northwest Airlines after it was absorbed by Delta Air Lines Inc.

United and Continental merged in October 2010 to form United Continental Holdings Inc. The two airlines still operate separately but are being combined into one airline that will fly under the United name. Federal labor law requires that unionized workers with similar jobs at the combined company choose one union or the other.

The Machinists won despite having fewer members eligible to vote in the election - roughly 6,800, compared to 7,300 Teamsters at Continental. The IAM won by 311 votes out of 10,835 cast, according to the federal National Mediation Board, which ran the election.

The IAM and the airline will now need to negotiate a contract that covers the combined group.

The airline is also in talks with pilots for a single contract. Pilots at both airlines were already in the Air Line Pilots Association before the merger. The talks have been taking longer than the company hoped and are now expected to last into 2012.

Shares of Chicago-based United Continental rose 87 cents, or 5.2 percent, to US$17.88 in afternoon trading.