As of June 2015, tickets can be purchased online using American Airlines AAdvantage miles. Travelers interested in using their miles to purchase tickets should go to the AAdvantage page on the American Airlines website. Form there, they can click on "book award travel" to purchase tickets online.
AAdvantage miles can be used on American Airlines and US Airways flights. They can also be used to upgrade flights on British Airways and Iberia and to purchase flights on oneworld partner airlines. Travelers can check the awards charts provided by American Airlines to determine the number of miles needed to purchase their desired flight before booking online.