The first phase of American Airlines’ narrowbody renewal program is starting to take shape with confirmation that the airline plans to lease 130 Airbus A319s and A321s, starting in 2013.

Few concrete details are being offered by the carrier, and it still is unclear how many of each type American intends to add to its fleet. In addition, questions remain about the 100 Boeing 737NGs also discussed during American’s big fleet announcement in July, although the comments from American indicate that the Boeing leases could include more than one variant.

American’s public statements reinforce the financial as well as operational benefits of adding both the A319 and A321, even though the aircraft will be powered by different, newly upgraded engines not fitted to any aircraft of the current fleet. The conclusion, though, is that the financing packages, and associated maintenance contracts, arranged through Airbus really are as attractive as American indicated back in July.

The airline also indicated that the leases announced Monday are for 10 years, which will allow American to return the aircraft before significant maintenance costs are incurred. This is another incentive to trial new aircraft and engine types before the larger, more expensive Airbus NEO and Boeing MAX aircraft arrive in 2017.

The A321s are a replacement for at least some of the 124 Boeing 757-200s American operated at the end of the third quarter. The European narrowbodies, and possibly the 737-900ER, also will replace transcontinental Boeing 767-200ER services, but with only 15 of those in the fleet, the loss of domestic widebody services will be minimal.

American’s A319 plans are a little more interesting, as there is no simple, one-for-one swap with the 211, 140-seat MD-80s currently operated by the U.S. legacy. Indeed, under the new offer to its pilots, American has plans for a new “SNB” or small narrowbody operation whose pilots will have different pay rates and work rules than other mainline crews. Without further details or a ratified pilot agreement, though, it is unclear how the A319 will be integrated into American’s fleet.

American also confirmed plans to add 15 more Boeing 777s to its fleet. Under current delivery plans, this includes two -300ERs in 2012, seven more in 2013, and two -200ERs each year from 2014 to 2016.