ANC23LA065

The pilot’s continued flight into moderate to severe icing conditions, including supercooled large droplets, over mountainous terrain, which resulted in a loss of control and impact with terrain. Contributing to the accident was the National Weather Service forecast that underestimated the area and intensity of the icing conditions and the lack of Alaska-specific icing graphics readily accessible to the pilot for preflight planning.

The instrument-rated pilot and passenger departed on a cross-country flight over mountainous terrain. The airplane departed an airstrip near the pilot’s residence about 0850 with a planned stop in Ketchikan, Alaska, before continuing to Washington state. The pilot established contact with an Anchorage Air Route Traffic Control Center controller when the flight was at 12,000 ft mean sea level (msl) about 25 minutes after departure. The controller advised the pilot he would need to climb to a higher altitude due to terrain and weather. The pilot responded that the airplane was turbocharged and that a higher altitude would not be a problem. The controller instructed the pilot to climb to 14,000 ft and advised him that, due to the remoteness and terrain, he might lose contact with the controller and issued backup frequencies. At 0953 the controller approved the pilot’s request to climb to 15,000 ft; there was no further communication from the pilot. The next day, a search and rescue crew located the wreckage, but terrain and poor weather conditions precluded reaching the site. The National Park Service overflew and photographed the site and concluded that, due to the unique challenges posed by the accident location, neither the occupants nor the wreckage would be recovered. The pilot obtained three preflight weather self-briefings from ForeFlight with a planned cruising altitude of 13,000 ft. Between the second and final briefing, the pilot requested the maximum icing severity image, icing potential for 11,000 ft and 12-hour icing forecast, and the 18,000 ft winds aloft forecast. Archived versions of the icing product viewed by the pilot were not available in the ForeFlight database or available from the NWS and the products the pilot requested were only available for the contiguous United States and were not created for the Alaska region. Weather soundings, forecasts, and experimental weather images depicted a greater than 70% probability of moderate to heavy icing above 12,000 ft through 15,000 ft. Data also indicated that the icing threat increased as the accident airplane climbed from 14,000 ft to 15,000 ft. Based on the weather data, the airplane likely encountered supercooled large droplet (SLD) conditions during the last minutes of the flight that degraded the airplane’s performance and resulted in a loss of control. According to the airplane pilot’s operating handbook (POH), flight into known icing conditions was prohibited. The National Weather Service (NWS) had issued advisories for instrument flight rules (IFR) and mountain obscuration conditions over the area; low clouds and precipitation were also present. The NWS area forecast and Alaska Aviation Weather Unit (AAWU) graphic icing forecasts were for isolated moderate icing in clouds between 17,000 ft and 22,000 ft, with the freezing level identified at 14,000 ft. However, the NWS underestimated the area and intensity of the icing conditions over the region and did not have in-flight advisories in effect around the time of the accident for all altitudes affected by icing. The pilot completed his instrument rating in the contiguous United States about two months before the accident, where the graphic map display of current and forecast icing products would have been available to him during his training. It’s likely he was looking for these images in ForeFlight, but they were not available for Alaska. Although the icing information was available to the pilot in a vertical cross-section chart, the graphic map that displayed areas of icing along his route of flight would have been familiar to him and visually consistent with other popular weather mapping products. Access to the icing information in this format would have given him the best opportunity to select a different route. Additionally, although the graphic icing information in Alaska was not available to the public or pilots, it was available to Alaska Flight Service weather briefers; however, the pilot did not obtain a formal weather briefing. Due to the expansive mountainous terrain in the area of the accident, there were no options for the pilot to exit icing conditions once he entered them. The pilot was unable to access icing products that were familiar to him, his airplane was not equipped for flight in icing conditions, yet he selected the riskier route over the mountains. After inadvertent flight into icing conditions, he did not notify air traffic control of his situation or initiate a 180° turn to exit icing conditions.

The pilot’s logbook was not obtained during the investigation. The pilot’s total flight time was recorded from his most recent FAA airman medical application dated June 12, 2023. The pilot acquired an instrument rating in June, in Texas where he lived, about two months prior to the accident. According to a mechanic who worked on the airplane, the pilot had been in Alaska and planned a trip to Washington state to visit family for a few days before returning to Alaska for the start of moose season. He planned the route from Glennallen to Ketchikan, then to Washington state because he preferred not to fly through Canada. Review of the airplane’s Pilot Operating Handbook, Section 2, KINDS OF OPERATIONS, includes a warning that, "FLIGHT IN ICING CONDITIONS PROHIBITED.” On August 27, 2023, about 1000 Alaska daylight time, a Beech B36TC airplane, N6709Q, was destroyed when it was involved in an accident near Cape Yakataga, Alaska. The pilot and passenger were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The airplane departed Snowshoe Lake Airport (5AK4), Glennallen, Alaska, at 0850, destined for Ketchikan, Alaska. A review of preliminary air traffic control (ATC) communications and ADS-B data from the FAA revealed that radar contact and radio communications were intermittent along the route of flight due to high terrain. About 0915 the pilot stated he was in visual flight rules (VFR) conditions at an altitude of 12,500 ft mean sea level (msl). The Anchorage Air Route Traffic Control Center (ARTCC) controller asked the pilot if he could climb higher, and the pilot responded that he would climb to 13,500 ft msl. About 0920, the controller confirmed radar contact with the airplane. The controller asked what the pilot’s requested final altitude was; the pilot replied 13,000 ft, and that he knew he had some weather ahead of him. The controller responded that he would encounter both weather and higher terrain and that he would need to climb higher. The pilot responded that they had oxygen onboard, the airplane was turbocharged, and a climb to a higher altitude would not be a problem. The controller then instructed the pilot to climb to 14,000 ft and the pilot subsequently confirmed that he would start the climb. At 0926, the controller told the pilot he would lose him on the active frequency and issued multiple backup frequencies to maintain radio communication. At 0928, the pilot established radio communications on a new frequency. The controller told the pilot that they would lose contact on all frequencies for about 10 minutes, then issued the current altimeter setting and provided the pilot another frequency to monitor. At 0938, the controller instructed the pilot to turn 20° to the right to avoid higher terrain along the route of flight but received no response. At 0945, the controller asked another airplane to relay instructions to the pilot of N6709Q, stating, in part, to make a 20° right turn and to climb to a higher altitude. At 0945, the pilot of the other airplane relayed a message to the controller that the pilot of N6709Q had acknowledged the updated instructions. At 0953, after reestablishing radio contact with the controller, the pilot of N6709Q requested a climb to 15,000 ft and the controller approved the request. At 0958, the controller stated “N6709Q, Anchorage center,” then again, “N6709Q, Anchorage center,” with no response from the pilot. The controller then asked another airplane to broadcast on the frequency to ask the pilot of N6709Q about his intentions. At 0958, the controller stated, “All other aircraft standby real quick, N6709Q, Anchorage center, you up? N6709Q, I see you rapidly descending at 11,000.” There were no further communications from the pilot of N6709Q. According to archived ADS-B data, at 0957 the airplane reached its highest altitude of 14,950 ft, then began a left turn and rapid descent. At 0959 the final radar target was near the accident site at 8,875 ft and 138 knots groundspeed. The next day, the crew of a U.S. Coast Guard HC-130 airplane located the wreckage site near Mt. Leeper, located in the Wrangell-St. Elias National Park and Preserve, at an elevation of about 4,787 ft, but terrain and continued poor weather conditions precluded reaching the site (see figure 1).  Figure 1. Aerial image of the accident site, with red box depicting area of accident site. (Source: Alaska Rescue Coordination Center) On September 5, about 9 days after the accident, weather conditions improved briefly, and a National Park Service (NPS) ranger was able to fly over and photograph the accident site. The fragmented airplane wreckage came to rest in a highly crevassed area on the Yahtse Glacier that continually accumulates snow (see figure 3). A sizable portion of the airplane wreckage was found in a large snow crater on the snow- and ice-covered glacial terrain, with smaller portions of airplane wreckage observed adjacent to the crater.   On September 13, the Wrangell-St. Elias National Park and Preserve mountaineering team determined that due to the location, crevasse danger, and poor weather conditions, recovery of the airplane’s two occupants or wreckage would not be attempted. Figure 3. Aerial view of the accident site (National Park Service photo) Previous Related Recommendations The pilot obtained three self-briefings before the accident flight, and reviewed weather information from several sources, including multiple pages on the NWS AAWU website. The NWS AWC produced graphical forecast products (the CIP and the FIP) that depict the potential for significant icing, including SLD conditions, for the contiguous United States. However, a product depicting SLD was not available for the state of Alaska; if it had been, the accident may have been avoided. On May 24, 2022, the NTSB issued two safety recommendations regarding SLD icing conditions in Alaska. Safety Recommendation A-22-21 recommended that the FAA, in collaboration with the NWS, develop a graphical forecast showing the potential for SLD icing conditions in Alaska and make this information available to pilots. Safety Recommendation A-22-22 recommended that the NWS work with the FAA to develop a graphical forecast depicting potential areas of SLD icing conditions in Alaska and make this information available to pilots. Additionally, an article on planning a flight to and from Alaska is available on the FAA website. The article, “FAI FSS – Planning A Flight to Alaska,” encourages users to contact Flight Service to get a thorough preflight weather briefing before the flight. The pilot obtained three preflight weather self-briefings from ForeFlight with a planned cruising altitude of 13,000 ft. Between the second and final briefing, the pilot requested the maximum icing severity image, icing potential for 11,000 ft and 12-hour icing forecast, and the 18,000 ft winds aloft forecast. Archived versions of the icing product viewed by the pilot were not available in the ForeFlight database or available from the NWS. The NWS current icing potential (CIP) and forecast icing potential (FIP) products the pilot requested were only available for the contiguous United States and were not created for the Alaska region. The only icing information available to the pilot in the Foreflight weather briefing was on the vertical cross-section of the winds aloft, which also includes the winds aloft and turbulence. The vertical cross-section depicted a change of light to moderate turbulence by color shaded boxes with the corresponding values. The chart also included icing symbols, which ranged from trace to heavy icing between 14,000 and 16,000 ft. The freezing level was identified at 14,000 ft. The NWS Alaska Aviation Weather Unit (AAWU) issued the Significant Weather Prognostic Chart which depicted a large area of continuous precipitation over the interior of Al