Military helicopter pilots on a training flight over Washington, D.C., did not hear air traffic control directions to pass behind a passenger jet heading its way, investigators revealed on Friday.
With American Airlines Flight 5342 from Wichita, Kan., descending to land at Ronald Reagan Washington National Airport, the control tower warned the Black Hawk pilots to “pass behind” the looming aircraft seconds before the Jan. 29 midair collision.
But according to National Transportation Safety Board Chair Jennifer Homendy, the words “pass behind the” were cut from the transmission to the cockpit of the military chopper.
She said it wasn’t known why communication in the cockpit cut out or why those vital instructions were “not communicated” to the copter pilots.
The mystery is one of the leads NTSB is investigating in its attempt to discover the cause of the crash that killed 67 people when the Mitsubishi Bombardier passenger plane collided with a U.S. Army Sikorsky UH-60 Black Hawk above the Potomac River. It was America’s worst air crash since November 12, 2001, when 260 people died when a plane smashed into a New York neighborhood. Another five people were killed on the ground.
Homendy said investigators were also trying to determine whether there was confusion onboard the helicopter about its altitude around the time of the crash and if the pilots' wearing night-vision goggles had any bearing on their final moments.
In a second-by-second description, Homendy said there was an instructor pilot in the chopper carrying out an annual test on his fellow flyer as well as a night-vision exam.
They were using routes regularly employed by military craft over the Potomac, but investigators learned that at one point a couple of minutes before the collision, the pilot reported a height of 300 feet while the instructor said it was at 400 feet. “We don’t know why there was that discrepancy,” she said.
The radio tower appeared to alert the helicopter that oncoming traffic was “in sight” and passed on instructions to avoid it.
Until the final transmission to the helicopter, both the plane and helicopter pilots could hear instructions from the control tower, but couldn’t hear each other’s responses.
A “traffic, traffic” alert was passed on to the helicopter pilots with a message to pass behind the jet. It is this message, or at least part of it, that never reached the pilots.
Seven seconds before impact, the Black Hawk crew said it had “traffic in sight.” At that time, the copter was at 278 feet, but the NTSB accepts there may have been “conflicting information in the data.”
They said the altitude the pilots saw in their cockpit may not have been accurate.
“We will be investigating into what the Black Hawk pilots could and could not see,” said Momendy, who said there may be a number of reasons, including a malfunction of the altimeter on board the chopper.
“We are looking at the possibility that there may have been bad data where they saw something different inside the cockpit,” she added.
Investigators will also be looking into whether the night goggles used for the visibility study were a factor, she said.
