Determining what caused a glider pilot to turn sharply into high-voltage power lines Friday afternoon, destroying the glider and killing the pilot and sole occupant, will not be an easy task, federal air safety investigators said Saturday.
Investigators from the National Transportation Safety Board spent most of Saturday collecting pieces of wreckage from a debris field that extends over an area roughly the size of three football fields.
The Boulder County Coroner’s Office identified the pilot Saturday as Daniel J. Tengdin, 46, of Westminster.
The glider is registered to Boulder-based Mile High Youth Gliding Association.
Jason Aguilera, an NTSB air safety investigator, said the glider was being operated by a different company at the time of the crash.
Representatives of Mile High Gliding declined to comment.
Aguilera said investigators will be looking at every factor: “man, machine and environment.”
Witnesses described the glider banking sharply to the left before striking the power lines east of Baseline Reservoir in unincorporated Boulder County about 5:15 p.m. Friday. They said the glider came apart in the air, and the debris fell over open fields. The Dry Creek Trail runs through the debris field and remained closed Saturday.
Aguilera said the glider seems to have been flying at a low altitude before the crash.
“It’s unusual for a glider to be in this sort of proximity,” he said.
Investigators will be looking at how experienced the pilot was and whether he had any medical conditions, Aguilera said. They also will look at the maintenance records for the aircraft.
Aguilera said an initial examination of the wreckage indicates the flight control elements that allow a pilot to bank and steer appear to have been attached before the glider struck the power lines.
The NTSB will also look at environmental factors like wind and sun. There were wind gusts of between 17 and 21 mph at the time of the crash, Aguilera said.
There was clear visibility Friday afternoon.
The glider has a data-logging device, but it doesn’t provide as much information as the black boxes on airplanes. However, it might provide some information about whether the glider got caught in a downdraft or a thermal, Aguilera said.
Aguilera said investigators documented ground scars and metal markings Saturday to preserve perishable evidence about where the glider struck the lines and how it fell to earth.
A crew from Xcel Energy examined the power lines Saturday, as well.
