Five US firms are advising on the largest aircraft order in history after AMR Corporation, the owner of American Airlines, agreed to acquire a total of 460 planes from Airbus and Boeing in a transaction worth more than $38bn (£23.5bn), reports The Am Law Daily.

American Airlines is being advised by Gibson Dunn & Crutcher corporate partner Robert Little in Dallas and Debevoise & Plimpton aviation chair John Curry in New York as co-counsel on the Airbus negotiations.

Debevoise is a longstanding legal adviser to American, while the airline has also turned to Gibson Dunn in the past for litigation and regulatory work; however, landing a major assignment for American on the corporate side is a departure for the firm.

Gibson Dunn's Little, who joined the firm in January with four other partners from Vinson & Elkins, said: "We reached out to them earlier this year and said we'd love a shot to work on a transactional deal.

"Thankfully they realised they had some good folks in their own backyard, so we were able to get in there and seize the opportunity to prove ourselves, which I think we were able to do."

Missouri-based firm Husch Blackwell is also advising American on its negotiations with Boeing, while Simpson Thacher & Bartlett corporate partner Alan Brenner and intellectual property partner Lori Lesser are advising Airbus on the agreement with American. Dean Gerber, chair of the global transportation finance practice at Vedder Price in Chicago, also advised Airbus.

American, the fourth-largest US airline, is also the only major carrier in the country that has never filed for bankruptcy. Its fleet, however, is among the industry's oldest – something that will change dramatically under the deal that will see the airline provided with new planes through to 2025.

The Am Law Daily is a US affiliate title of Legal Week.