Still being shown in Pensacola
A Reviewer says that it left the IMAX theatres, but it is still being shown in the IMAX theatre at the National Museum of Naval Aviation, at NAS Pensacola, FL. I just saw it with my son's Cub Scout pack last month. It may be on a rotation schedule with other IMAX films.
http://www.navalaviationmuseum.org/explore/imax
It's a great film especially in the IMAX format and very educational about flight. The boys really enjoyed it.