History of Flight
On July 20, 2023, about 1105 Alaska daylight time, a Bell 206L-4 helicopter, registration N311MH, was destroyed when it struck terrain near Wainwright, Alaska. The pilot and three passengers were fatally injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 135 on-demand charter flight. It was owned and operated by Maritime Helicopters under an exclusive use contract with the State of Alaska’s Department of Natural Resources (DNR) for transporting scientific crews to remote locations in the North Slope region.
The helicopter departed Utqiagvik at about 1001. The planned route included a brief stop at Atqasuk Airport and then continued to remote sites east of Wainwright before returning to Utqiagvik. The helicopter was expected back by 2030. When it did not arrive, a North Slope Borough Search and Rescue Sikorsky S-92 helicopter was dispatched to search. The partially submerged, fragmented wreckage was found in the shallow waters of Lake Itinik, about 30 miles east of Wainwright. Lake Itinik is a large, oval-shaped arctic lake measuring more than three miles across. The surrounding terrain is flat, featureless arctic tundra at an elevation of about 56 feet above mean sea level.
The helicopter was equipped with a Honeywell Sky Connect Tracker system that broadcast flight status data every 3 minutes. Management and DNR personnel had real-time flight following. Sky Connect data showed the helicopter departed Utqiagvik at 1001, stopped at Atqasuk, then traveled northwesterly. At 1105, the data ended as the helicopter passed over the southeastern shoreline of Lake Itinik at 144 ft msl and 93 knots ground speed. At about 1112, the system sent an overdue report that went unnoticed. The helicopter was reported overdue at 2230 by a State of Alaska Geological Survey employee.
On a flight the day before, average altitude was about 200 ft msl and average airspeed about 105 knots. A pilot operating in the same area said that, in general, he flies around 800-1200 ft msl in poor weather and 3000-4000 ft msl in good weather. He commented that the accident helicopter's speed and altitude in that area was "too fast" at those altitudes.
Personnel Information
The accident pilot was a recent military retiree with about 1,900 hours of helicopter flight experience. He started with Maritime Helicopters in October 2022, initially flying a Bell 407, then transitioned to the Bell 206 series six months before the accident. He completed an exam on flat-light conditions on October 21, 2022, and a follow-up exam where he identified the North Slope as an area conducive to flat light. He arrived in Utqiagvik two days before the accident flight, which was his second flight with passengers in that area. The operator stated that flat light and overwater flight procedures are covered in their training program and Standard Operating Procedures (SOPs).
Aircraft Information
The operator's SOPs prohibit operation in flat featureless terrain unless in-flight visibility is at least one mile, a visual surface reference is available for a safe landing, and a visible horizon distinguishes sky and ground. Flat light conditions can occur over snow-covered terrain, calm water, or open water, making it difficult to discern topographical features, altitude, and attitude. One SOP-identified hazard is controlled flight into terrain. The SOPs require float-equipped aircraft (fixed or emergency pop-out floats) for operations beyond power-off gliding distance from shore; the accident helicopter was not so equipped.
The operator's flight locating procedures require steps when an aircraft is more than 60 minutes overdue, including contacting the aircraft, other aircraft, the Flight Service Station, management, and eventually the NTSB and FAA. The operator reported that the accident pilot did not receive information about altitude flight restrictions required by the Alaska DNR permit. The operator does not have a Flight Operational Quality Assurance program and does not review flight history for unsafe behaviors.
A DNR chief familiar with the permit requirements stated that helicopter pilots typically fly higher than minimum altitudes and only descend due to weather. The Director of Operations said the company's pilots "fly as high as they can and avoids flying over water in poor weather conditions" and was unsure why the pilot flew so low and at that speed. The operator requires compliance with FAA altitude minimums, including 14 CFR §91.119, §135.203, and §135.207.
Meteorological Information
At departure from Utqiagvik (about 55 miles from the accident site, elevation 49 ft), the ceiling was about 200-300 ft agl and visibility 3-5 statute miles. The closest weather station was Atqasuk Edward Burnell Sr. Memorial Airport (27 miles southeast, elevation 101 ft). At 1105, automated weather reported wind 290° at 3 knots, visibility 10+ miles, sky clear, temperature 18°C, dew point 14°C, altimeter 29.90 inHg. At 1110, visibility dropped to 5 miles in haze, then returned to 10+ miles. Wainwright Airport (36 miles west) reported visibility 9 miles, sky clear.
Satellite imagery showed low stratiform clouds extending from Utqiagvik to near Atqasuk. The Fog Stability Index indicated favorable conditions for radiation fog. The Area Forecast included an AIRMET for IFR conditions over coastal and offshore sections, with ceilings below 1000 ft and visibility below 3 miles in light rain, mist, and fog. The National Weather Service's Flying Weather graphic depicted marginal VFR conditions. The pilot received a preflight weather briefing and requested a special VFR departure.
A pilot from another operator reported departing Utqiagvik to the southwest between 0900 and 1000 that day, with no ceiling, no altitude restrictions, no visibility issues, and calling it one of the warmest days he had seen.
Wreckage and Impact Information
A postaccident examination revealed that the fuselage was fragmented from impact forces with the water. All fractures were consistent with overload. Front-to-rear crushing consistent with frontal water impact was observed. The tailboom was fractured aft of the intercostal support. No preimpact anomalies were found in the tail rotor, elevator flight controls, or tail rotor driveshaft; all fractures were from overload. The main rotor hub and blades showed no preimpact anomalies. Both tail rotor blades were fractured chordwise, consistent with being under power at impact. Main rotor flight controls exhibited no preimpact anomalies. The engine showed no evidence of preimpact fire, damage, or malfunction. N1 and N2 turbine rotors rotated smoothly. The fuel control unit pointer was in the 100 (max) position. Clean fuel was detected. Oil was present and uncontaminated. No ferrous metal debris was found in the oil filter or chip detectors.
Medical and Pathological Information
The 48-year-old pilot's aviation medical examination on October 26, 2022 noted use of bilateral hearing aids. He was issued a second-class medical certificate with requirements for glasses for near vision and hearing amplification. An autopsy determined the cause of death as multiple blunt force injuries, manner of death accident. Postmortem toxicology detected cetirizine at 73 ng/mL in blood and 277 ng/g in liver tissue. The FAA states pilots should wait 48 hours after using cetirizine before flying.