American Airlines Inc. wants to replace its fuel-guzzling McDonnell Douglas MD-80 fleet a bit faster.

The Fort Worth-based carrier said Wednesday that it would take delivery of six more Boeing 737-800 aircraft in 2010.

The decision accelerates American's fleet renewal plan and means it will get 76 new 737-800s from 2009 to 2010 instead of 70.

The carrier said that it still has firm commitments for 11 737s in 2013 and is evaluating speeding up its plan to replace its MD-80s with additional 737s.

A spokesman for American declined to say how much the carrier was paying for its 737-800s, but the list price published by Boeing Co. puts the planes between $70.5 million and $79 million apiece.

This is the second time in four months that American has sped up its 737-800 deliveries.

The 300 narrow-body MD-80s that American had at the end of 2007 averaged 18 years in age and represented nearly half of the carrier's fleet.

American said last month that 30 of those planes would be grounded by Dec. 31 as it slashes its capacity.

The 737-800 is expected to be about 25 percent more fuel-efficient than the MD-80.

American also said that it has arranged backstop financing for about two-thirds of its Boeing 737-800 deliveries in 2009 and 2010.

All of American's 2009 deliveries may be financed under the agreement should American elect to do so. Additional details of the financing arrangement were not disclosed.

Shares of American's parent, AMR Corp., fell $1.33, or 10.9 percent, to close at $10.86.