To the credit of British writer-director Paul Greengrass (Bloody Sunday), this taut, partly speculative account of the 9/11 flight that crashed in a Pennsylvania field has practically none of the exploitative melodrama one would expect from a major studio release. The film cuts between the delayed Newark-to-San Francisco flight, a military air-defense facility, and air-traffic-control centers in Boston and New York (with some of the real-life participants playing themselves), then switches to real time once the plane takes off. Greengrass takes pains to keep events believable and relatively unrhetorical, rejecting entertainment for the sake of sober reflection, though one has to ask how edifying this is apart from its reduction of the standard myths. (One myth it perpetuates is that the passengers succeeded in storming the cockpit before the plane crashed.) R, 111 min. (JR)