Mountains

The single engine airplane departed Us-Khatyn on a flight to Suordakh, carrying five passengers, two pilots and a load consisting of 600 kilos of various goods. While cruising at an altitude of about 1,450 metres, the crew encountered moderate atmospheric turbulences and was unable to maintain the altitude. The aircraft lost height and crashed on the rocky slope of amountain located 15 km southeast from the Lake Siljan-Kuel, some 250 km from the destination. Two passengers were killed while five others occupants were injured. The aircraft was destroyed.

At 1101 Pacific Daylight Time on 06 August 2019, the Alkan Air Ltd. Cessna 208B Grand Caravan aircraft (registration C‐FSKF, serial number 208B0673) departed Rau Strip, Yukon, on a visual flight rules company flight itinerary to Mayo Airport, Yukon. The aircraft had 1 pilot, 1 passenger, and cargo on board. At 1113, the aircraft entered instrument meteorological conditions and struck rising terrain in a box canyon shortly after. The crash occurred approximately 25 nautical miles east‐northeast of Mayo Airport, at an elevation of 5500 feet above sea level. The Canadian Mission Control Centre did not receive a signal from the aircraft’s 406 MHz emergency locator transmitter. Eyewitnesses from a nearby exploration camp arrived at the site after approximately 1 hour. Royal Canadian Mounted Police and emergency medical services arrived on site approximately 90 minutes after the accident. The pilot and passenger received fatal injuries. The aircraft was destroyed; there was a brief post‐impact fire.

Seair Seaplanes (Seair) was contracted by a remote fishing lodge on the central coast of British Columbia (BC) (Figure 1) to provide seasonal transport of guests and supplies between Vancouver International Water Aerodrome (CAM9), BC, and the lodge, which is located about 66 nautical miles (NM) north-northwest of Port Hardy Airport (CYZT), BC, and about 29 NM southeast of Bella Bella (Campbell Island) Airport (CBBC), BC. On 26 July 2019, the occurrence pilot arrived at Seair’s CAM9 base at approximately 0630. Over the next hour, the pilot completed a daily inspection of the Cessna 208 Caravan aircraft (registration C-GURL, serial number 20800501), added 300 L of fuel to the aircraft, and began flight planning activities, which included gathering and interpreting weather information. On the morning of the occurrence, 4 Seair visual flight rules (VFR) flights were scheduled to fly to the central coast of BC, all on Caravan aircraft: C-GURL (the occurrence aircraft) was to depart CAM9 at 0730, C-GSAS at 0745, C-FLAC at 0800, and C-GUUS at 0900. The first 3 flights were direct flights to the fishing lodge, while the 4th flight had an intermediate stop at the Campbell River Water Aerodrome (CAE3), BC, to pick up passengers before heading to a research institute located approximately 4 NM southwest of the fishing lodge. Because of poor weather conditions in the central coast region, however, all of the flights were delayed. After the crews referred to weather cameras along the central coast region, the flights began to depart, but in a different order than originally scheduled. It is not uncommon for the order of departure to change when groups of aircraft are going to the same general location. One of Seair’s senior operational staff (operations manager) departed CAM9 at 0850 aboard C-FLAC. C-GUUS, bound for the research institute, departed CAM9 next at 0906, and then the occurrence aircraft departed at 0932 (Table 1). The pilot originally scheduled to fly C-GSAS declined the flight. This pilot had recently upgraded to the Caravan, had never flown to this destination before, and was concerned about the weather at the destination. When Seair’s chief pilot returned to CAM9 at 0953 after a series of scheduled flights on a different type of aircraft, he assumed the last remaining flight to the lodge and C-GSAS departed CAM9 at 1024.After departing the Vancouver terminal control area, the occurrence aircraft climbed to 4500 feet above sea level (ASL) and remained at this altitude until 1023, when a slow descent was initiated. The aircraft levelled off at approximately 1300 feet ASL at 1044, when it was approximately 18 NM northeast of Port Hardy Airport (CYZT), BC, and 57 NM southeast of the destination. At 1050, the occurrence aircraft slowly descended again as the flight continued northbound. During this descent, the aircraft’s flaps were extended to the 10° position. At this point, the occurrence aircraft was 37 NM south-southeast of the fishing lodge. The aircraft continued to descend until it reached an altitude of approximately 330 feet ASL, at 1056. By this point, the occurrence aircraft was being operated along the coastline, but over the ocean. C-FLAC departed from the fishing lodge at 1056 on the return flight to CAM9. C-FLAC flew into the Fitz Hugh Sound and proceeded southbound along the western shoreline. At approximately 1100, it flew through an area of heavy rain where visibility was reduced to about 1 statute mile (SM). C-FLAC descended to about 170 feet ASL and maintained this altitude for the next 5 minutes before climbing to about 300 feet ASL. As the southbound C-FLAC entered Fitz Hugh Sound from the north at Hecate Island, the occurrence aircraft entered Fitz Hugh Sound from the south, near the southern tip of Calvert Island. The occurrence aircraft then changed course from the western to the eastern shoreline, and descended again to about 230 feet ASL (Figure 2), while maintaining an airspeed of approximately 125 knots. The 2 aircraft established 2-way radio contact. The pilot of C-FLAC indicated that Addenbroke Island was visible when he flew past it, and described the weather conditions in the Fitz Hugh Sound to the occurrence pilot as heavy rain showers and visibility of approximately 1 SM around Kelpie Point. The occurrence pilot then indicated that he would maintain a course along the eastern shoreline of the sound. At 1103, the 2 aircraft were separated by 2 NM and passed each other on reciprocal tracks, approximately 4 NM south of the accident site. The occurrence aircraft maintained a consistent track and altitude for the next 54 seconds, then slowly began a 25° change in track to the west (0.35 NM from the Addenbroke Island shoreline). Seven seconds after the turn started (0.12 NM from the island’s shoreline), the aircraft entered a shallow climb averaging 665 fpm. At 1104:55, the occurrence aircraft struck trees on Addenbroke Island at an altitude of approximately 490 feet ASL, at an airspeed of 114 knots, and in a relatively straight and level attitude. The aircraft then continued through the heavily forested hillside for approximately 450 feet, coming to rest at an elevation of 425 feet ASL, 9.7 NM east-southeast of the destination fishing lodge. The pilot and three passengers were killed and five other occupants were injured, four seriously.

At approximately 1000LT on 12 July 2019, a private de Havilland DHC-2 Mk. 1 Beaver floatplane (registration C‑GRHF, serial number 1123) took off from the St-Mathias Water Aerodrome (CSV9), Quebec, with only the pilot on board, for a series of visual flight rules (VFR) flights. The aircraft landed at approximately 1130 on Désert Lake in La Minerve, Quebec, and came alongside a private dock where 3 individuals were waiting to board and fly to a fishing lodge. Once the baggage was stowed on the aircraft, the pilot provided a safety briefing to the passengers, who were all wearing a personal flotation device. The aircraft took off from Désert Lake at approximately 1215, bound for the Barrage Gouin Water Aerodrome (CTP3), Quebec, where the aircraft was scheduled to be refuelled. The aircraft landed at approximately 1430. Once the refuelling was complete, the aircraft took off once again around 1528, headed northwest to Weakwaten Lake, Quebec, where the fishing lodge was located. After approximately 48 minutes of flight, at around 1616, the aircraft collided with trees and struck the ground. There was no post-impact fire. The emergency locator transmitter was activated by the force of impact, and began transmitting a signal on frequency 121.5 MHz. This signal was detected by the flight crew of a commercial airliner at 1705 and reported to air traffic services. At 1850, the Joint Rescue Coordination Centre in Trenton dispatched a CC130 Hercules aircraft to try to locate the distress signal. The occurrence aircraft was found in a densely wooded area at 2032. Two search and rescue technicians were parachuted to rescue the aircraft occupants. Three of the 4 occupants received fatal injuries. The survivor was evacuated and transported to the hospital in Chibougamau, Quebec.

The crew departed Kyren Airport on a crop spraying mission to treat forests. About 40 minutes into the flight, while flying at a speed of 140 km/h, the crew encountered downdrafts and the airplane lost height. Due to mountainous terrain, the crew made a turn to the right but the airplane continued to descend. The captain attempted an emergency landing when, at a speed of 85 km/h, the aircraft struck trees and crashed in a wooded area located 16 km southeast of Dabady. Both pilots were injured and evacuated to Irkutsk a day later. The aircraft was damaged beyond repair.

The airplane departed Jorhat Airport at 1227LT on a flight to Mechuka, Arunachal Pradesh. About half an hour later, while in cruising altitude, radio and radar contact were lost. SAR operations were quickly initiated and the wreckage was spotted eight days later, on June 11, by the crew of a Mil Mi-17 helicopter. The wreckage was found at an altitude of 12,000 feet in a wooded and steep area, about 16 km north of Lipo and 32 km east of Mechuka Airport. The aircraft was totally destroyed and all 13 occupants were killed.

On 01 May 2019 at 0723, the aircraft departed CYYR on a VFR flight plan direct to BGBW. The ferry pilot, who was the pilot-in-command, occupied the left seat while the co-owner occupied the right seat. The aircraft climbed to 2000 feet ASL and proceeded on a direct track to destination. The altitude and heading did not change significantly along the route, therefore it is likely that the autopilot was engaged. At 0816, the aircraft collided with a snow-covered hill 2250 feet in elevation, located 35 nautical miles (NM) southeast of Makkovik Airport (CYFT), Newfoundland and Labrador. The impact happened approximately 200 feet below the top of the hill. The aircraft came to rest in deep snow on steep sloping terrain. The aircraft sustained significant damage to the propeller, nose gear, both wings, and fuselage. Although the cabin was crush-damaged, occupiable space remained. There was no post-impact fire. The ferry pilot was seriously injured and the co-owner was fatally injured. The Joint Rescue Coordination Centre (JRCC) in Halifax received an emergency locator transmitter (ELT) signal from the aircraft at 0823. The ferry pilot carried a personal satellite tracking device, a personal locator beacon (PLB) and a handheld very high frequency (VHF) radio, which allowed communication with search and rescue (SAR). Air SAR were dispatched to the area; however, by that time, the weather had deteriorated to blizzard conditions and aerial rescue was not possible. Ground SAR then deployed from the coastal community of Makkovik and arrived at the accident site approximately 4 hours later because of poor weather conditions and near zero visibility. The ferry pilot and the body of the co-owner were transported to Makkovik by snowmobile. The following day, they were airlifted to CYYR.

On 8 December 2018, the pilot of a Pilatus Britten-Norman BN2A-20 Islander, registered VH-OBL and operated by Airlines of Tasmania, was conducting a positioning flight under the visual flight rules from Cambridge Airport to the Bathurst Harbour aeroplane landing area (ALA), Tasmania. The aircraft departed Cambridge at about 0748 Eastern Daylight-saving Time and was scheduled to arrive at Bathurst Harbour about 0830 to pick up five passengers for the return flight. The passengers were part of a conservation project that flew to south-west Tasmania regularly, and it was the pilot’s only flight for that day. Automatic dependent surveillance broadcast (ADS-B) position and altitude data (refer to the section titled Recorded information) showed the aircraft tracked to the south-west towards Bathurst Harbour (Figure 1). At about 0816, the aircraft approached a gap in the Arthur Range known as ‘the portals’. The portals are a saddle (lowest area) between the Eastern and Western Arthur Range, and was an optional route that Airlines of Tasmania used between Cambridge and Bathurst Harbour when the cloud base prevented flight over the mountain range. After passing through the portals, the aircraft proceeded to conduct a number of turns below the height of the surrounding highest terrain. The final data point recorded was at about At about 0829, the Australian Maritime Safety Authority received advice that an emergency locator transmitter allocated to VH-OBL had activated. They subsequently advised the Tasmanian Police and the aircraft operator of the activation, and initiated search and rescue efforts. The rescue efforts included two helicopters and a Challenger 604 search and rescue jet aircraft. The Challenger arrived over the emergency locator transmitter signal location at around 0925, however, due to cloud cover the crew were unable to visually identify the precise location of VH-OBL. A police rescue helicopter arrived at the search area at about 1030. The pilot of that helicopter reported observing cloud covering the eastern side of the Western Arthur Range, and described a wall of cloud with its base sitting on the bottom of the west portal. Multiple attempts were made throughout the day to locate the accident site, however, due to low-level cloud, and fluctuating weather conditions, the search and rescue operation was unable to confirm visual location of the aircraft until about 1900. The aircraft wreckage was found in mountainous terrain of the Western Arthur Range in the Southwest National Park (Figure 2) . The search and rescue crew assessed that the accident was unlikely to have been survivable. The helicopter crew considered winching personnel to the site, however, due to a number of risks, including potential for cloud reforming, the time of day and lighting, and other hazards associated with the mountainous location, the helicopter departed the area. The aircraft wreckage was accessed the following day, when it was confirmed that the pilot was fatally injured.

On 11 August 2018, a PAC 750XL aircraft registered PK-HVQ was being operated by PT. Marta Buana Abadi (Dimonim Air) on unscheduled passenger flight from Tanah Merah to Oksibil. At the day of the occurrence the meteorological condition at Oksibil was below the requirement of Visual Flight Rule (VFR) weather minima and did not improve. Being aware that some flights had performed flight to Tanah Merah to Oksibil and returned, the pilot decided to fly to Oksibil. At 1342 LT, on daylight condition the PK-HVQ aircraft departed from Tanah Merah to Oksibil, on board the aircraft were one pilot, one observer pilot and 7 passengers. According to the passenger and cargo manifest, the total weight of passenger and the baggage were 473 kg. Prior to the departure, there was no record or report of aircraft system malfunction. At 1411 LT, the PK-HVQ pilot made initial contact to Oksibil Tower controller and reported that the aircraft was maintaining altitude of 7,000 feet over and the estimate time arrival at Oksibil would be 0520 UTC (1420 LT). The Oksibil Tower controller advised the pilot of the latest meteorological condition that the visibility was 1 up to 2 km and most of the area were covered by cloud. At 1416 LT, the pilot reported that the aircraft position was over Oksibil Aiport and the Oksibil Tower controller instructed the pilot to continue the flight to the final runway 11 and to report when the runway had in sight. The Oksibil Tower controller and pilots of other aircraft called the pilot but no reply. On the following day, the aircraft was found on a ridge of mountain about 3.8 Nm north west of Oksibil on bearing 331° with elevation about 6,800 feet. Eight occupants were fatally injured and one occupant was seriously injured.

The commercial pilot was conducting a 1-hour commercial air tour flight over Denali National Park and Preserve with four passengers on board. About 48 minutes after departure, the Alaska Rescue Coordination Center received an alert from the airplane's emergency locator transmitter. About 7 minutes later, company personnel received a call from the pilot, who reported that the airplane had run "into the side of a mountain." Although a search was initiated almost immediately, due to poor weather conditions in the area, the wreckage was not located until almost 36 hours later in a crevasse on a glacier about 10,920 ft mean sea level. Due to the unique challenges posed by the steepness of terrain, the crevasse, avalanche hazard, and the condition of the airplane, neither the occupants nor the wreckage were recovered from the accident site. A weather model sounding for the area of the accident site estimated broken cloud bases at 700 ft above ground level (agl) with overcast clouds at 1,000 ft agl and cloud tops to 21,000 ft agl and higher clouds above. The freezing level was at 9,866 ft and supported light-to-moderate rime type icing in clouds and precipitation. The on-scene assessment indicated that the right wing impacted snow while the airplane was flying in a wings-level attitude; the right wing had separated from the remainder of the wreckage. Based upon available weather data and forecast models and the impact evidence, it is likely that the pilot entered an area of reduced visibility and was unable to see the terrain before the airplane's right wing impacted the snow. The company's organizational structure was such that one group of management personnel oversaw operations in both Anchorage and Talkeetna. Interviews with company management revealed that they were not always aware of the exact routing a pilot would take for a tour; the route was pilot's discretion based upon the weather at the time of the flight to provide the best tour experience. Regarding risk mitigation, the company did not utilize a formal risk assessment process, but rather relied on conversations between pilots and flight followers. This could lead to an oversight of actual risk associated with a particular flight route and weather conditions. About 8 months after the accident, an assessment flight conducted by the National Park Service determined that during the winter, the hazardous hanging glacier at the accident site calved, releasing an estimated 4,000 to 6,000 tons of ice and debris. There was no evidence of the airplane wreckage near the crash site, in the steep fall line, or on the glacier surface over 3,600 ft below. Although the known circumstances of the accident are consistent with a controlled flight into terrain event, the factual information available was limited because the wreckage was not recovered and no autopsy or toxicology of the pilot could be performed; therefore, whether other circumstances may have contributed to the accident could not be determined.