United Continental Holdings Inc., formed from a 2010 merger of the two airlines, said on Wednesday that it received approval from the Federal Aviation Administration (FAA) to operate as a single airline, a significant milestone for the world's largest airline.

Roughly 14 months after United and Continental airlines merged, the FAA granted the unified company a single operating certificate, allowing it to operate flights as one entity.

While we have much work ahead of us as we integrate these two great carriers, this is a significant milestone, Jeff Smisek, United's chief executive, said in a statement.

The company, which continued to fly as two airlines during the integration period, said the government recognition will not have any immediate effect on customer dealings.

Customers will continue to shop for flights, get seat assignments, check flight status, and make other arrangements on each carrier's respective website until it fully combines services in the beginning of 2012.

The company will maintain separate flight crews until contract issues are settled with all unions and seniority lists have been integrated.

With the FAA approval, the company will officially operate as United Airlines and the Continental name will cease to exist (though it will remain part of the holding company name). The FAA approval also means that air traffic control communications will now refer to all United and Continental flights as United.

According to the company, a team of more than 500 employees worked toward getting FAA approval. Some 440 operation manuals, procedures, and programs were combined and trimmed to about 260 manuals for the new United - a process that involved approximately 2,000 changes.

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For some, the FAA announcement may come as a surprise. Many changes were already made bringing the two airlines closer to a unified brand. These customer-oriented changes do not require FAA approval.

The company repainted the majority of the aircraft with a new logo and made steps toward merging frequent-flier programs that go into effect Jan.  1. In most airports across the nation, the airline has combined gates and check-in facilities and rebranded lounges as United Club. In the cabin, there is a single onboard menu and in-flight magazine for both United and Continental planes.

United purchased Continental last year in a $3.17 billion all-stock deal to form the world's largest airline company.