NTSB finds radio failures preceded Marine One near-miss with regional jet

Investigators in the United States have laid out how a breakdown in communication contributed to a near-miss between the presidential helicopter and a regional airliner at Washington National Airport on 4 August.

Preliminary findings from the National Transportation Safety Board show that the Sikorsky VH-3D helicopter, flying under the callsign Marine One, was preparing to leave a temporary landing site near the White House known as The Ellipse. Construction work had forced the helicopter to operate from that location instead of its usual site.

The crew tried twice to notify the airport's helicopter controller of an imminent take-off, using the standard three-minute warning call. Neither transmission came through clearly. Controllers heard only what was described as an unintelligible transmission and issued an advisory saying the message had been broken and unreadable. A separate attempt to relay the warning through a nearby military base also failed.

About three minutes after the helicopter crew's first call, a tower controller cleared an Envoy Air Embraer 170 bound for Pensacola to take off from runway 1. The jet's crew got a traffic advisory from their collision-avoidance system but never spotted the helicopter visually. It passed roughly 0.82 nautical miles to their right.

The NTSB noted that concerns about the reliability of these radio warnings had come up just five days earlier, at a meeting between air traffic control staff and the helicopter squadron responsible for presidential transport. The investigation into the loss-of-separation event continues.