N4087G

On November 29, 2019, about 1911 Alaska standard time, a Piper PA-31-350 airplane, N4087G, was destroyed when it was involved in an accident near Cooper Landing, Alaska. The three occupants; the airline transport pilot, a flight nurse, and the flight paramedic were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 135 air ambulance flight.

Dispatch records indicated that, on November 29, Providence Seward Medical Center emergency clinic personnel contacted multiple air ambulance companies with a "weather check" for possible air ambulance transportation of a patient from Seward Airport (PAWD) to Ted Stevens Anchorage International Airport (PANC), Anchorage. The first company contacted was Guardian Flight, who declined the flight at 1624 due to limited daylight hours. The second company, LifeMed Alaska, declined the flight at 1637 due to weather. The third and final company contacted for the flight was Medevac Alaska. Their dispatch officer was not notified of the previous declined flight requests and forwarded the request to Security Aviation, who is their sole air charter provider. At 1731 Security Aviation accepted the flight, and Medevac Alaska flight SVX36 was staffed with a nurse and paramedic.

A review of Federal Aviation Administration (FAA) radar and automatic dependent surveillance (ADS-B) data revealed that the accident airplane departed PANC and flew south about 3,000 ft mean sea level (msl) toward the Sterling Highway. The airplane was then observed descending to 2,200 ft msl while flying a right racetrack pattern before flying into the valley toward Cooper Landing. The last data point indicated at 1911:14 the airplane was over the west end of Jean Lake at 2,100 ft msl, on a 127° course, and 122 kts groundspeed (see figures 1 and 2).

Figure 1. Preliminary flight track

Figure 2. Preliminary end of flight track and accident site

Ground witnesses who were in vehicles on the Sterling Highway near milepost 63, reported that they saw the lights of the airplane flying over the highway that night. One witness stated that he saw the airplane west of the mountains turn in a circle as it descended and then entered the valley. He observed the wings rocking back and forth and while he was looking elsewhere, he heard an explosion and observed a large fire on the mountainside. Another witness reported seeing the airplane flying low and explode when it impacted the mountain. Witnesses to the fire called 911 and observed the wreckage high on the mountainside burning for a long time after impact.

The airplane was reported overdue by the chief pilot for Security Aviation and the FAA issued an alert notice (ALNOT) at 2031. The Alaska Rescue Coordination Center dispatched an MH-60 helicopter to the last known position and located the burning wreckage that was inaccessible due to high winds in the area.

On December 1, 2019, the Alaska State Troopers coordinated a mountain recovery mission with Alaska Mountain Rescue Group. The wreckage was observed on the mountain at an elevation of about 1,425 ft msl in an area of steep, heavily tree-covered terrain near the southeast end of Jean Lake in the Kenai National Wildlife Refuge. The airplane was highly fragmented and burned, however all major airplane components were accounted for. Multiple large trees around the wreckage were fractured and indicated an easterly heading prior to the initial impact (see figure 3).

Figure 3. Accident site

A postaccident examination of the airplane revealed flight control continuity was confirmed from the cockpit to the flight controls; broomstraw features or cuts made by recovery personnel were noted at the separation points (no evidence of fatigue separation was noted). A measurement of the aileron trim screw roughly correlated to neutral aileron trim. The left engine was impact separated from the engine mount and displayed impact damage. The left propeller was impact separated from the engine at the crankshaft flange; one propeller blade was bent opposite of the direction of rotation, one blade was bent aft about 90°, and one blade was curled forward about 90°. The right engine remained attached to the engine mount and displayed thermal and impact damage. The right propeller remained attached to the engine; one blade displayed leading edge dents and indentations and chordwise scraping, one blade displayed chips on its leading edge and the tip was deformed and folded, and one blade displayed S-bending and leading-edge denting.

The route from Anchorage to Seward is about 75 nautical miles southeast across the Kenai Peninsula and the Kenai Mountains. The coastal town of Seward is located at the north end of a fjord surrounded by mountains ranging from 4,000 ft to 6,000 ft elevation. Seward Airport instrument approach procedures prohibit night instrument flight rules approaches.

The closest weather reporting facility was the Soldotna Airport (PASX), about 30 nautical miles west of the accident site. The 1856 observation included wind from 250° at 3 knots, 10 statute miles (sm) visibility, broken clouds at 8,000 ft and 9,500 ft, temperature 36°F, dewpoint 36°F, and altimeter 29.56 inches of mercury. The US Naval Observatory sunset time on the day of the accident was 1554. Witnesses reported dark night conditions and gusting winds in the area.

The PAWD special (SPECI) weather observation for 1623 included wind calm, 3 sm visibility in light rain and mist, clouds broken at 4,800 ft and 5,500 ft, overcast at 7,000 ft. The 1653 observation included wind from 020 at 3 knots, 8 sm visibility in light rain and mist, overcast clouds at 4,200 ft. The 1753 observation included winds from 120 at 3 knots, visibility 5 sm in light rain, and clouds few at 200 ft, overcast at 4,600 ft.

Several unofficial surface observations sites were closer to the accident site than PASX and PAWD. The recorded observations from these sites indicated gusty surface wind conditions with wind gusts between 13 and 27 knots and an east to southeast wind direction. In addition, one of the sites reported precipitation accumulation of 0.01 inches between 1956 and 2056 AKST.

Satellite weather data depicted a low-pressure system over the Gulf of Alaska with an occluded front stretched northward over the southern Kenai Peninsula. A cold front stretched southward from the Kenai Peninsula over the eastern Gulf of Alaska. The accident site was located north of the occluded and cold frontal boundaries on the cold air side of the fronts.

Graphical forecasts valid for the accident time warned of marginal visual flight rules (MVFR) to instrument flight rules (IFR) conditions, a surface wind greater than 30 knots, low-level wind shear (LLWS), and moderate icing above 6,000 ft msl at the accident site or along the route of flight. Additionally, the area forecast for the accident location and the route of flight to PAWD warned of occasional broken ceilings at 2,500 ft msl with light rain showers, visibilities between 3 and 5 miles in light snow showers and mist, and occasional broken ceilings at 4,500 ft msl with isolated light rain showers. In the vicinity of Anchorage, a surface wind from the southeast at 25 knots with gusts to 45 knots were forecast.

A Weather Research and Forecasting Model (WRF) simulation was run to simulate the weather conditions surrounding the time of the accident. The WRF simulation indicated the airplane was in an area of rapidly transitioning updraft and downdrafts with magnitudes of 1,500 feet per minute (fpm) near the accident time. The WRF simulation also indicated that the accident site was in an area of 30 to 40 knot wind speeds with wind speeds above 50 knots near the mountain top level (between 2,500 and 3,500 ft msl).

An autopsy of the pilot was performed by the State of Alaska Medical Examiner’s Office, which listed the cause of death as “multiple blunt force and thermal injuries.”