Army Report Links Pentagon Equipment Glitch to Aborted Landings at D.C. Airport

Two commercial flights were diverted from Ronald Reagan National Airport on May 1 in part because of a communications glitch between an Army Black Hawk helicopter and Pentagon air traffic controllers, according to an Army official who was briefed on an internal review of the matter.

The Black Hawk helicopter had tried to land on the helipad near the Pentagon but was asked to fly around and land a short while later, according to an Army statement issued Friday. That request, which came from air traffic controllers at the Pentagon, arose from a short period in which the controllers lost audio and visual contact with the helicopter just moments before it was set to land, the official said.

The helicopter “initiated a go-around due to a delay in clearance from the Pentagon Tower,” the Army wrote in its statement. The Associated Press earlier reported details of the Army review.

The Federal Aviation Administration and the National Transportation Safety Board are also investigating the event and declined to comment.

The May 1 episode, which included the aborted landings of a Delta Air Lines flight and a Republic Airways flight, has been under unusual scrutiny because of the recent spate of problems in U.S. aviation.

In January, a midair collision near National Airport between a different Army Black Hawk helicopter and a commercial flight from Wichita, Kan., killed 67 people. And in recent weeks, air traffic control centers from Philadelphia to the Denver area have been affected by equipment outages that have frightened controllers, raising concerns about air safety.

The F.A.A. oversees the National Airport air traffic control tower and has been working to address the equipment and staffing troubles. At a Senate hearing last week, Franklin McIntosh, then the deputy chief operating officer of the F.A.A., said that his agency had not known until the May 1 episode that a hotline linking the Pentagon’s controllers to their counterparts at the National Airport tower had been inoperable for three years. In the meantime, the two entities were communicating over a landline, officials have said.

“We were extremely troubled by the incident that occurred,” Mr. McIntosh said, adding that the Defense Department had suspended certain operations in the National Airport airspace afterward. A repaired hotline would be necessary in order for the flights to resume, the F.A.A. official added.

The aviation agency recently restricted a particularly treacherous helicopter flight route in the National Airport vicinity and mandated that Army flights operate with a location broadcasting system called ADS-B Out. The Army said on Friday that the Black Hawk in the May 1 episode was using ADS-B Out at the time and that it was also flying on an approved route.