Mechanics at American Airlines are being courted by three different unions to represent a new bargaining unit in Tulsa that will be formed when the airline merges with US Airways this year. The workers are currently represented by the Transport Workers Union, which negotiated a contract with the airline in August that included better health benefits and a 15% raise over six years, as well as provisions for the merger. The airline says that they are staying neutral.
See "Unions battle to represent American Airlines' mechanics", Kyle Arnold, USA Today, April 14, 2013