The National Transportation Safety Board says two May helicopter crashes in Southeast Alaska, one of which left a pilot dead, took place during glacier flights where visibility was affected.
The NTSB released preliminary reports Tuesday on the May 6 Denver Glacier crash 4 miles southeast of Skagway which killed 59-year-old Temsco Helicopters pilot Christopher Maggio, as well as the Norris Glacier crash roughly 15 miles northeast of Juneau which injured 39-year-old Jiri Hanis of Era Helicopters a day earlier.
NTSB investigator Mike Hodges, who recently transferred from the board's Seattle office to Anchorage, responded to both crash sites. He said conditions affecting visibility were a common link between the crashes.
"For the Juneau accident (Hanis) reported flat light conditions, and then on the Skagway one we have initial reports of poor visibility in the area," Hodges said.
A Federal Aviation Administration safety website describes flat light conditions as an optical illusion caused by overcast skies, which can pose a significant threat to pilots.
"Flat light can completely obscure features of the terrain, creating an inability to distinguish distances and closure rates," FAA officials wrote. "As a result of this reflected light, it can give pilots the illusion of ascending or descending when actually flying level."
According to the NTSB, both men were flying Airbus AS-350 helicopters to dog-sledding camps on the respective glaciers. Hanis told investigators his helicopter crashed at about 2:10 p.m. while on approach to the Norris Glacier site.
"(Hanis) said that while on approach to the site, over a large, featureless, and snow-covered ice field, flat light conditions made it very difficult to discern the topographical features of the snow-covered ice field below," investigators wrote. "The helicopter subsequently struck the snow-covered ice field, and rolled over to the right. The pilot characterized the accident as controlled flight into terrain."
The Denver Glacier report said Maggio was able to land and offload a passenger, as well as a dozen dogs, at his destination. His chopper took off to return to Temsco's Skagway heliport but crashed at about 7 p.m. near a frozen glacial lake. Searchers found its wreckage after Maggio was reported overdue.
"The helicopter flew towards the previously used aerial return route to the southwest, and then the helicopter turned and flew to the north," investigators wrote. "Visibility was reported for the previously used aerial return route as about 1/4 mile, and to the north of the dog sledding camp visibility was reported as about 1/2 mile."
The AS-350 that crashed near Juneau has been recovered, Hodges said.
Work is still in progress to retrieve the helicopter from the crash site near Skagway.
Alaska Dispatch Publishing