NTSB: Flight descended to 2,200 feet before entering mountain valley where it crashed
A plane that crashed near Cooper Landing late last month made an unexplained loop in its course before crashing into the mountains, according to a preliminary report from the National Transportation Safety Board.
The preliminary accident report released Wednesday gives new details about the ill-fated Security Aviation flight that crashed on Nov. 29, killing all three onboard.
According to the report, Providence Seward Medical Center emergency clinic personnel contacted three air ambulance companies about the potential to transport a patient from Seward to Anchorage.
As previously reported, both Guardian Flight and LifeMed Alaska declined to take the flight. According to the NTSB Preliminary Report, Guardian’s decision was based on limited daylight hours, while LifeMed’s decision was due to weather.
The report also says that the dispatch officer for Medevac Alaska, the company providing the medical team, was not notified of the two declined offers and forwarded the request to Security Aviation, Medevac's sole air charter provider.
According to Clint Johnson, regional chief for Alaska for the National Transportation Board, dispatchers usually are notified if other carriers decline a flight. He said it was unclear why Medevac Alaska wasn't notified and that the ongoing investigation will attempt to determine that.
Security Aviation accepted the offer around 5:31 p.m., about an hour and a half after the predicted sunset time by the US Naval Observatory. The flight departed the Anchorage Airport at around 6:48 p.m.
Johnson says that a big part of the ongoing investigation will be determining what the standard operating procedures are for flying at night in the area.
“We are looking at what is standard operating procedures,” he said.
According to the report, the plane, a Piper PA-31-350, flew at about 3,000 feet toward the Sterling Highway on its way to Seward. At some point, the plane was observed to be descending to 2,200 feet while flying at a right racetrack pattern, a hard right turn into a loop, before continuing in the valley toward Cooper Landing.
Johnson said that it's unknown why the plane made that maneuver but that it wasn’t a standard practice for flying that route.
The last data point showed that around 7:11 p.m., the plane was over the west end of Jean Lake along the Sterling Highway at about 2,100 feet heading southeast at 127 degrees flying about 140 mph ground speed.
A witness interviewed by NTSB said he was in a vehicle near Mile 63 of the Sterling Highway said he saw the plane turn in a circle as it descended and entered the valley with wings rocking back and forth. He then heard an explosion and saw a large fire on the mountainside.
Another witness said they saw the plane flying low and explode upon impact. Witnesses called 911 as they watched the wreckage burn “for a long time after impact.”
When the Alaska Rescue Coordination Center dispatched an MH-6 helicopter to the last known position of the craft, the crew located the burning wreckage but decided it wasn’t recoverable at the time due to high winds.
Two days later on Dec. 1, the Alaska State Troopers along with the Alaska Mountain Rescue group sent a team on a recovery mission. When they arrived at the crash site, around 1,425 feet through tree-covered terrain at the Southeast end of Jean Lake, they found that the plane was “highly fragmented and burned” but they were able to account for all of the major components.
Broken trees around the crash site suggested that the plane was heading east prior to crashing.
About 10 miles of visibility was reported at the weather station in Soldotna about 35 miles from the crash site, with winds about 3 mph from the north, though witnesses reported gusting in the area.
A weather station in Seward suggested lower visibility of around 5 statute miles with light rain and light clouds at 200 feet.
According to Johnson, 10 miles of visibility could mean that visibility was perfect, but it’s standard in aviation not to report more than 10. He said that the distance between the weather stations and the accident site made actual conditions difficult to determine.
“They were a long way away so we don’t really know what the weather was in the area so we’re really having to rely on what witnesses in the area have told us,” he said.
The investigation team also has a meteorologist assigned to the investigation who will be looking at weather models and satellite imagery from the time of the accident to try to deduce what the actual conditions were in the valley.
Johnson said that Security Aviation has been “really cooperative” with the ongoing investigation.