The US defence department is to release a video of the plane crashing into the Pentagon on 11 September 2001, legal rights group Judicial Watch has said.
The US will release the previously unseen footage at 1300 (1700 GMT).
American Airlines Flight 77 crashed into the US military headquarters,
killing 184 people, after it was hijacked as part of an al-Qaeda plot.
The release of the video, taken from a Pentagon security camera, comes after a freedom of information act request.
Judicial Watch said it would release the footage as soon as it could, but it was not clear when that would be.
The group filed the request in 2004, but the Pentagon refused to release the video because it was part of the investigation involving al-Qaeda plotter Zacarias Moussaoui, the group said.
Judicial Watch filed a lawsuit this February, arguing that there was "no legal basis" for the refusal.