BOULDER COUNTY, Colo. — One of the planes involved in a midair collision last month that killed three people wasn't automatically transmitting signals of its position, as required for airspace around Denver International Airport (DIA).
The collision between a Cessna 172 and a Sonex Xenos happened Sept. 17 east of Niwot, with both airplanes crashing nose-down into a field. An instructor and student were aboard the Cessna, and one person was in the Xenos.
A preliminary report from the National Transportation Safety Board (NTSB) said that the Cessna was equipped with required automatic dependent surveillance-broadcast (ADS-B) equipment and was transmitting data during the flight, but the Xenos was not.
The Xenos, a homemade lightweight, aluminum, two-seat aircraft registered to Henry Butler, 69, had not transmitted an ADS-B signal since July 14 – about two months before the crash.
ADS-B transmissions are required within DIA airspace. The transmissions provide continuous updates on a plane’s location using navigation satellites to other planes and air traffic controllers.
Neither plane was in radio contact with air traffic control, which is not required, the report says.
The Cessna took off from Rocky Mountain Municipal Airport in Broomfield at 8:43 a.m. on Sept. 17, and the Xenos departed Platte Valley Airpark in Hudson at 8:38 a.m.
Both planes climbed to about 7,000 to 7,500 feet and flew toward the Longmont area, with the Cessna going north and the Xenos going west. The Cessna did a 360-degree turn and then headed east just before the planes "merged," the report says.
Pieces of the outboard left wings of both airplanes were found in a field below the point where they crashed.
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An earlier assessment of the aircraft showed that neither aircraft was equipped with a collision avoidance system or any kind of display in the cockpit to alert the pilot to other aircraft in the area. They were not required by the Federal Aviation Administration (FAA) to have those capabilities.
The Boulder County Coroner's Office identified the victims as Daniel Wilmoth, 22; Samuel Fisher, 23, and Butler, 69.
> Below: Raw Sky9 footage of both of the downed planes in the crash:
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