British Airways PLC (BAIRY) Thursday said it was close to finalizing information requested by the U.S. allowing the airline to expand a key transatlantic alliance.

BA and its main partner, AMR Corp.'s (AMR) American Airlines, want to secure antitrust immunity alongside other members of the Oneworld alliance to coordinate their global operations.

The U.K. carrier said it hoped to secure approval from the U.S. by September or October, though observers believe the timetable could be challenged by opposition from U.S. lawmakers and some rival carriers.

An influential U.S. lawmaking committee was considering Thursday the introduction of language to a bill that could derail the existing system of alliances that dominate the global airline industry.

BA and American have twice tried and failed to secure antitrust immunity, or ATI, after regulators suggested conditions regarded by the airlines as too onerous.

Their latest submission, made last year, would bring their alliance closer to the rival SkyTeam and Star groupings, many of whose members are allowed to coordinate marketing and schedules after securing ATI approval.

The U.S. Department of Transportation asked the Oneworld carriers for more information on Dec. 19 and, as of Feb. 25, hadn't received it, according to a DOT filing.

BA said Thursday that "information gathering is close to an end," adding that it expects a decision from the Transportation Department by September or October.

The U.K. airline said it would target benefits from the planned cooperation by 2010 if it wins approval.

American said Wednesday that it hadn't submitted the additional information to the DOT, but was targeting approval "in the second half of the year."

When the DOT rules the application is "substantially complete," it has six months to make a ruling. However, rival airlines could challenge the decision and delay the process, said industry observers in Washington, D.C.

The House transportation committee is also considering language for a bill that would call for a review of the impact of global alliances on competition and even cancel existing ATI approvals after three years.

The U.S. Air Transport Association warned in a letter to the committee chairman Wednesday that such terminations would be "tremendously unfair" and cost up to 15,000 airline jobs.

Given that the joint applicants are requesting global immunity, the DOT required further information on worldwide plans and operations, including the alliance's plans and operations in the Pacific, Australian and Latin American markets.

In addition, the DOT called for additional detail about hub rationalization and code-sharing, as well as how a joint business agreement would affect corporate and travel agency relationships.

-By Kaveri Niththyananthan, Dow Jones Newswires; 4420 7842 9299; kaveri.niththyananthan@dowjones.com

-By Doug Cameron, Dow Jones Newswires; 312-750-4135; dougcameron@dowjones.com