N410B

On July 20, 2024, about 1421 Alaska daylight time, a Beech A35 airplane, N410B, was destroyed when it was involved in an accident near Gustavus, Alaska. The pilot and two passengers were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

According to a friend of the occupants, the pilot and two passengers departed the Juneau International Airport (PAJN), Juneau, Alaska, on a flight bound for the Yakutat Airport (PAYA), Yakutat, Alaska. The friend alerted search and rescue personnel about 1713 reporting that the airplane was two hours overdue.

An FAA alert notice was issued at 1757, and search and rescue crews were dispatched to the last known point on the accident airplane’s route; however, poor weather conditions hampered the search.

According to ADS-B data, the accident airplane departed Juneau about 1344 and initially headed northwest for about 72 miles. The airplane’s track then changed direction to a southwesterly heading and began flying through the mountainous terrain of Glacier Bay National Park for an additional 30 miles. (See figure 1.)

Figure 1. Accident airplane’s ADS-B track through Glacier Bay National Park.

About 1421, as the airplane’s flight track continued along a westerly heading of 245°, at an altitude of 10,875 ft msl, and with a groundspeed of 141 kts, the flight track abruptly ended on the eastern side of East Crillon mountain. The elevation of the terrain above the last data point was about 11,220 ft msl. The down sloping terrain on the eastern side of East Crillon mountain consisted of expansive vertical rock, snow-covered terrain, and hanging glaciers, with areas of widespread glacial crevasses directly below. (See figure 2.)

Figure 2. Accident airplane’s ADS-B track.

The closest weather reporting station, located in Gustavus, Alaska, about 54 miles southeast of the accident site, at 1356, reported that the ceiling was overcast at 600 ft above ground level (agl) variable to 1,100 ft agl, with 10 miles visibility.

A preliminary NTSB weather study showed Aviation Weather Center (AWC) Graphical Forecasts for Aviation (GFA) data indicating cloud bases as low as 2,200 ft msl and tops no lower than 12,000 ft msl in the accident region, with surface visibilities less than 0.25 statute miles. The High-Resolution Rapid Refresh (HRRR) model, provided by the National Oceanic and Atmospheric Association (NOAA), suggested the presence of clouds from 3,000 ft msl to 12,500 ft msl in the accident region. The National Weather Service (NWS) had issued an AIRMET for mountain obscuration in the accident region.

The United States Coast Guard, Alaska Air National Guard, and Civil Air Patrol conducted extensive search and rescue efforts in the area surrounding East Crillon mountain.

Search personnel reported finding what was believed to be an initial impact site, marked by a V-shaped upslope terrain disturbance near the last known ADS-B data point on the accident airplane’s flight track. The site was in an area of very steep, and in some areas vertical, snow- and ice-covered terrain. The area around the airplane’s suspected initial impact site appeared to have had recent avalanche activity, which would have carried any airplane wreckage downslope. Search and rescue crews deemed the suspected initial impact site as inaccessible due to the high elevation, significant avalanche danger, and inclement weather.

On August 5, an aerial search of the accident site and the surrounding area revealed portions of highly fragmented airplane wreckage on the eastern side of East Crillon mountain about 6,260 ft msl. The portions of wreckage were found more than 4,500 ft below the suspected initial impact site, and spread out over an area of rough, steep, and crevasse-covered glaciated terrain. (See figure 3.)

Figure 3. ADS-B track of accident airplane with reference to downslope wreckage location.

Portions of the fragmented wreckage were subsequently identified as belonging to the accident airplane by comparing photos of the airplane’s distinctive paint scheme with photos of the wreckage.

Global Data Assimilation System model soundings for near the accident were retrieved from NOAA’s Air Resources Laboratory and analyzed by the RAwinsonde OBservation (RAOB) program. RAOB noted scattered clouds about 2,800 ft, with broken to overcast cloud layers above that to about 13,000 ft around the time of the accident.

The freezing level was identified at 9,900 feet, and the potential for light rime icing was identified between about 10,000 and 12,000 feet.

An AIRMET advisory SIERRA for “mountains occasionally obscured by clouds/precipitation,” with no change expected during the AIRMET’s valid period or the 6-hour period beyond that, was issued by the Alaska Aviation Weather Unit (AAWU) and was valid for an area that included the accident site at the time of the accident.

An Area Forecast for the region of the accident location was issued by the AAWU before the time of the accident. This Area Forecast included the AIRMET information, and for the area south of Eldred Rock forecast few clouds at 300 ft, scattered clouds at 1,200 ft, ceiling broken at 3,500 ft with cloud tops to 12,000 ft, and occasional ceiling broken at 1,200 ft with light rain showers. No significant turbulence or icing was forecast.

A review of the pilot’s flight logs indicated that the last recorded actual or simulated instrument flight time occurred more than five years before the accident. No additional instrument flight time was logged after that date. Maintenance records showed that, at the time of the accident, the airplane had not undergone the inspections required under Federal Aviation Regulations for instrument flight. Additionally, there was no evidence that the pilot obtained a preflight weather briefing from an official source.