Aug 8 (Reuters) - A U.S. agency will announce Friday it

is opening an investigation into the government's management of

airspace around Reagan Washington National Airport after a fatal

Jan. 29 collision between an American Airlines ( AAL ) regional

jet and Army helicopter killed 67.

The U.S. Transportation Department Office of Inspector

General is auditing the Federal Aviation Administration's

management of airspace and its allowance of exemptions of the

use of a key safety system by some military aircraft, according

to a document seen by Reuters.