AAR said the exercise of the option by the U.S. Transportation Command is worth about $143 million.
Under the option, which is to a 2008 award, AAR will continue to provide the military with rotary-wing aircraft and related personnel, equipment and maintenance and personnel for the transport of cargo and mail in support of U.S. and NATO operations in Afghanistan.
AAR is using 10 heavy-lift Sikorsky S-61 and two medium-lift Puma SA 330J helicopters for the contract.
"The extension reflects the U.S. government's continued confidence in our ability to meet the arduous demands of supporting tactical airlift missions in challenging environments," said AAR Airlift President Randy Martinez. "AAR is committed to providing the Department of Defense with critical military support to sustain its operations in Afghanistan and around the world."