WASHINGTON, July 30 (Reuters) - The National

Transportation Safety Board opened a three-day investigative

hearing Wednesday into the fatal collision in January between a

U.S. Army helicopter and an American Airlines ( AAL ) plane that

killed 67 near Reagan Washington National Airport.

The NTSB will review the Army Black Hawk helicopter air data

systems and altimeters as well as the Federal Aviation

Administration's oversight of Washington airspace and air

traffic. One key focus is the performance of the helicopter

altimeter and the helicopter's altitude at the time of the

crash.

(Reporting by David Shepardson; Editing by Chizu Nomiyama )