BELL 206-L4

Full Narrative

HISTORY OF FLIGHTOn July 20, 2023, about 1105 Alaska daylight time, a Bell 206L-4 helicopter, N311MH, was destroyed when it was involved in an accident near Wainwright, Alaska. The pilot and three passengers were fatally injured. The helicopter was operated by the pilot as a Title 14 Code of Federal Regulations Part 135 on-demand charter flight.
The helicopter was owned and operated by Maritime Helicopters and was under an exclusive use contract to the State of Alaska’s Department of Natural Resources (DNR), being used to transport scientific crews to various remote locations within the North Slope region.
Maritime Helicopters’ Director of Operations reported that the accident helicopter and DNR crew members were based in Utqiagvik (formerly Barrow), Alaska, for the duration of the contract. He added that when the accident helicopter departed from Utqiagvik, about 1001, the anticipated route included a brief stop at the Atqasuk Airport, Atqasuk, Alaska, and then continuing to remote sites to the east of Wainwright, before ultimately returning to Utqiagvik. The accident helicopter was expected to return to Utqiagvik by 2030. When the helicopter did not arrive back in Utqiagvik, a North Slope Borough (NSB) Search and Rescue Sikorsky S-92 helicopter was dispatched to search for the missing helicopter.
The partially submerged, fragmented helicopter 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 in some areas. The terrain around Lake Itinik consists of flat, featureless, arctic tundra-covered terrain. The elevation of Lake Itinik is about 56 ft above mean sea level (msl).
The accident helicopter was equipped with a Honeywell Sky Connect Tracker system enabling real-time flight following capabilities. The Sky Connect Tracker system broadcasts flight status data in 3-minute intervals to satellite-based receivers. Management personnel from Maritime Helicopters, as well as personnel from DNR had real-time flight following capabilities of the accident helicopter.
A review of the archived Sky Connect data revealed that the accident helicopter departed from Utqiagvik about 1001; it then proceeded southwest to the Atqasuk Airport. After a brief stop at the Atqasuk Airport, the helicopter departed and traveled in a northwesterly direction. At 1105, the Sky Connect data ends as the helicopter passed over the southeastern shoreline of Lake Itinik, while continuing to travel in a northwesterly direction, at an altitude of 144 ft msl with a ground speed of 93 knots.
At about 1112 the Sky Connect system sent out an overdue aircraft report, but that report went unnoticed by the operator or the DNR. The helicopter was reported overdue at 2230 by an employee of the State of Alaska Geological Survey.

On a flight the day before the accident, Sky Connect Tracker system flight data revealed an average altitude of about 200 ft msl with an average airspeed of about 105 knots.
A helicopter pilot operating in the same area said, in general, if there is poor flying weather, he will fly around 800 to 1,200 ft msl. With no weather restrictions, he will fly between 3,000 and 4,000 ft msl. When asked about the speed and altitude of the accident helicopter was flying at, he said based on his experience in that area that was “too fast” at those altitudes. PERSONNEL INFORMATIONThe accident pilot recently retired from the military; this was his first job as a pilot since retirement. He had about 1,900 hours of flight experience in helicopters. He started with the company in October of 2022. Initially he was assigned to the Bell 407 helicopter, but six months before the accident he transitioned to the Bell 206 series helicopter. As part of his initial training, the pilot completed an exam on flat-light conditions on October 21, 2022. On a follow up exam, the pilot identified the North Slope as an area conducive to flat light conditions. The pilot arrived in Utqiagvik two days before the accident flight. The accident flight was his second flight with passengers in the Utqiagvik area. According to the operator, flat light flight procedures are covered in their training program, and overwater flight procedures are covered in their Standard Operating Procedures (SOP’s). AIRCRAFT INFORMATIONThe operator’s SOP’s state that helicopters will not be operated in areas of flat featureless terrain unless the in-flight visibility is at least one mile, a visual surface reference is available which would allow for a safe landing area, and a visible horizon is present that distinguishes the sky and ground. According to the SOP’s, flat light conditions can be present in a variety of areas ranging from snow-covered terrain to over open water.
Flat light is a visual condition where sunlight is diffused by, but not limited to, overcast skies, coupled with flat and featureless terrain, calm water, or snow-covered terrain. Flat light conditions in these environments contribute to the pilot’s ability to discern topographical features below making it difficult to determine the altitude and/or attitude of the aircraft. One of the hazards associated with overwater operations identified by the operator in their SOP’s is controlled flight into terrain.
The operator’s SOP’s also require only float equipped aircraft (fixed or emergency pop-out floats) to be operated beyond power-off gliding distance from shore. The accident helicopter was not equipped with fixed or emergency pop-out floats.
Title 14 CFR §135.207 helicopter surface reference requirements. No person may operate a helicopter under VFR unless that person has visual surface reference or, at night, visual surface light reference, sufficient to safely control the helicopter.
The operator’s flight locating procedures shall be provided by:
A local Flight Service Station, through the use of a filed FAA flight plan including Company phone contact; or, a designated company or customer flight monitor through the use of a Company VFR flight plan. These flight locating procedures will be immediately available to the designated flight monitor.
In the event a company aircraft operating on a company flight plan is more than 60 minutes overdue from the latest ETA, or if an emergency signal is indicated by the aircraft flight following system. The following steps shall be taken by the designated flight monitor.
1. Attempt to contact the aircraft.
2. Contact other company aircraft, company personnel at the remote site, the customer or any other operators in the surrounding area and ask them to try to contact the overdue aircraft through their available communication methods.
3. Call the closest Flight Service Station, identify the flight and request any information and possible FSS contact.
4. Notify company management. Identify the aircraft and its location on the Sky Connect Tracker computer display, and explain any pertinent information about the flight.
5. If the aircraft has not been located after accomplishing steps 1 through 4 call NTSB and the FAA 24-hour response phone number to report the flight overdue.
The operator reported that the accident pilot did not receive the information concerning the altitude flight restrictions that were required by the Alaska DNR permit.
The operator does not have a Flight Operational Quality Assurance program and does not review flight history to detect unsafe behaviors.
A chief at the Alaska DNR who had extensive knowledge of the requirements of the permit to operate in the area, was familiar with the mission the crew was conducting, and who had flown numerous times in the area reported that helicopter pilots would fly a lot higher than the minimum altitude and would only go lower because of the weather as stipulated in the permit.
The Director of Operations for the operator said “they fly as high as they can and avoids flying over water in poor weather conditions.” The only time they fly low is because of poor weather. He was not sure why the pilot would choose to fly so low and at that speed.
The operator requires their pilots to comply with FAA altitude minimums, to include 14 CFR §91.119, 14 CFR §135.203 and 14 CFR §135.207. METEOROLOGICAL INFORMATIONWhen the accident helicopter departed PABR, which was about 55 miles from the accident site at an elevation of 49 ft, the ceiling was about 200 to 300 ft agl and visibility was about 3 to 5 statute miles.

The closest weather reporting location to the accident site was Atqasuk Edward Burnell Sr. Memorial Airport (PATQ), located about 27 miles southeast of the accident site at an elevation of 101 ft. The weather conditions were light winds, visibility was 10 miles or more, and sky conditions were clear. About 5 minutes after the accident the visibility was reported as 5 miles and haze. These conditions were present for about 15 minutes and then returned to 10 miles or more.

PATQ weather at 1105 AKDT, automated, wind from 290° at 3 knots, visibility 10 miles or more, sky clear below 12,000 ft, temperature 18° C, dew point 14° C, altimeter 29.90 inHg. PATQ weather at 1110 AKDT, automated, wind from 240° at 5 knots, visibility 5 miles in haze, sky clear below 12,000 ft, temperature 18° C, dew point 14° C, altimeter 29.90 inHg.

The next closest reporting location was from Wainwright Airport (PAWI), Wainwright, Alaska, located 36 miles west of the accident site at an elevation of 45 ft. The weather conditions about the time of the accident were reported as visibility 9 miles, sky clear below 12,000 ft agl.

Satellite imagery of the accident site revealed the presence of low stratiform clouds that extended from PABR and ended near PATQ. The Fog Stability Index indicated favorable conditions for the formation of radiation type fog.

Due to fiber optic outages, there were a limited number of FAA weather camera images available. There were no images from the closest weather camera (PATQ) facing the accident site (northwest); however, images to the north revealed clear skies. The images to the southwest depicted a scattered layer of low stratiform clouds and a mid-layer of altostratus clouds. The PAWI camera images toward the accident site displayed scattered high-level clouds.

The Area Forecast noted that an AIRMET for IFR conditions was current for the coastal and offshore sections over PABR to near PAWI, with ceilings below 1,000 ft agl and visibility below 3 miles in light rain, mist, and fog.

The National Weather Service’s Alaska Aviation Weather Unit Flying Weather graphic valid for the time of the accident depicted marginal VFR conditions.

According to the FAA Barrow Flight Service Station, the pilot received a preflight weather briefing and requested a special VFR departure.

Weather camera images near the accident site revealed no cloud coverage and unrestricted visibility.

A pilot from a different operator reported that he was operating in the same area as the accident helicopter. He stated he departed Utqiagvik (PABR) to the southwest on the day of the accident, between 0900 and 1000. He said there was no ceiling, no altitude restrictions, and no issues with visibility. The temperature that day was one of the warmest days he had ever seen. When he returned to Utqiagvik that night, he noticed the accident helicopter was not back yet. It was very unusual for him to be back before the accident helicopter. He called the FAA flight service center with his concern but was told they had no flight plan and no information on when the accident helicopter was returning. AIRPORT INFORMATIONThe operator’s SOP’s state that helicopters will not be operated in areas of flat featureless terrain unless the in-flight visibility is at least one mile, a visual surface reference is available which would allow for a safe landing area, and a visible horizon is present that distinguishes the sky and ground. According to the SOP’s, flat light conditions can be present in a variety of areas ranging from snow-covered terrain to over open water.
Flat light is a visual condition where sunlight is diffused by, but not limited to, overcast skies, coupled with flat and featureless terrain, calm water, or snow-covered terrain. Flat light conditions in these environments contribute to the pilot’s ability to discern topographical features below making it difficult to determine the altitude and/or attitude of the aircraft. One of the hazards associated with overwater operations identified by the operator in their SOP’s is controlled flight into terrain.
The operator’s SOP’s also require only float equipped aircraft (fixed or emergency pop-out floats) to be operated beyond power-off gliding distance from shore. The accident helicopter was not equipped with fixed or emergency pop-out floats.
Title 14 CFR §135.207 helicopter surface reference requirements. No person may operate a helicopter under VFR unless that person has visual surface reference or, at night, visual surface light reference, sufficient to safely control the helicopter.
The operator’s flight locating procedures shall be provided by:
A local Flight Service Station, through the use of a filed FAA flight plan including Company phone contact; or, a designated company or customer flight monitor through the use of a Company VFR flight plan. These flight locating procedures will be immediately available to the designated flight monitor.
In the event a company aircraft operating on a company flight plan is more than 60 minutes overdue from the latest ETA, or if an emergency signal is indicated by the aircraft flight following system. The following steps shall be taken by the designated flight monitor.
1. Attempt to contact the aircraft.
2. Contact other company aircraft, company personnel at the remote site, the customer or any other operators in the surrounding area and ask them to try to contact the overdue aircraft through their available communication methods.
3. Call the closest Flight Service Station, identify the flight and request any information and possible FSS contact.
4. Notify company management. Identify the aircraft and its location on the Sky Connect Tracker computer display, and explain any pertinent information about the flight.
5. If the aircraft has not been located after accomplishing steps 1 through 4 call NTSB and the FAA 24-hour response phone number to report the flight overdue.
The operator reported that the accident pilot did not receive the information concerning the altitude flight restrictions that were required by the Alaska DNR permit.
The operator does not have a Flight Operational Quality Assurance program and does not review flight history to detect unsafe behaviors.
A chief at the Alaska DNR who had extensive knowledge of the requirements of the permit to operate in the area, was familiar with the mission the crew was conducting, and who had flown numerous times in the area reported that helicopter pilots would fly a lot higher than the minimum altitude and would only go lower because of the weather as stipulated in the permit.
The Director of Operations for the operator said “they fly as high as they can and avoids flying over water in poor weather conditions.” The only time they fly low is because of poor weather. He was not sure why the pilot would choose to fly so low and at that speed.
The operator requires their pilots to comply with FAA altitude minimums, to include 14 CFR §91.119, 14 CFR §135.203 and 14 CFR §135.207. WRECKAGE AND IMPACT INFORMATIONA postaccident wreckage examination revealed that the fuselage was fragmented from impact forces with the water. All observed fractures were consistent with overload forces from impact. Evidence of front-to-rear crushing consistent with frontal water impact forces was observed at the cockpit seat structure, copilot door, and right cabin door. The aft fuselage was relatively intact but heavily damaged from impact forces. The four tailboom attachment bolts and nuts were all solidly attached. The tailboom exhibited a fracture consistent with impact overload just aft of the intercostal support at the forward end of the tailboom. No preimpact anomalies were observed in the tail rotor, elevator flight controls, or tail rotor driveshaft system; all observed fractures were consistent with overload impact forces.
All tail rotor driveshaft segments on the tail boom rotated freely by hand and corresponding rotation to the tail rotor blades through the tail rotor gearbox was observed. No unusual noises were heard when the tail rotor gearbox was rotating. All Thomas couplings and hanger bearings on the tailboom were intact. Tail rotor gearbox support fractures were observed at both the left forward and left aft locations where the gearbox attaches, and all were consistent with overload forces. No chips were observed on the tail rotor gearbox chip detector. Remnants of oil were observed in the gearbox.
No preimpact anomalies were observed in the main rotor hub and blades. Both main rotor blades remained connected to the hub at the blade grips. The main rotor blade grips and pitch horns all remained intact and attached. One main rotor blade was fractured at the outboard doublers that was consistent with impact forces. The other main rotor blade was cut during recovery approximately ¼ of the way from the blade grip. This main rotor blade was relatively intact from root to tip with a slight bend opposite the direction of rotation consistent with impact while rotating. Both tail rotor blades were fractured chordwise in overload, consistent with being under power at impact. No preimpact anomalies were observed in the main rotor flight controls and hydraulics; all observed fractures were consistent with overload forces at impact. Most of the main rotor flight controls were missing and not recovered and all fractures were consistent with overload at impact. The cyclic stick was fractured at its base consistent with overload forces.
The three main rotor servos were found impact damaged but relatively intact. All three servo bodies were able to be moved by hand through their respective servo pistons. The servo support remained attached to the fractured roof structure. The servo manifold exhibited several fractured lines consistent with overload fractures. The connection from the servo input valve lever arms to their respective wiredrive assemblies were all intact with no evidence of joint looseness observed. The outer ring rotating swashplate rotated freely by hand. The swashplate support was fractured near its base consistent with the mast bending just above the transmission top case from impact forces. One main rotor pitch change link (PCL) was fractured consistent with overload forces in the middle of the link and at the bottom of the link near the bottom clevis insert. The other PCL was bent but not fractured.
The fuel spray nozzle was removed and examined. The air shroud on the nozzle tip contained a typical amount of light carbon layer that had been contaminated with rusty brown like debris indicative of lake water exposure. The nozzle appeared internally clear of debris and was not disassembled further. No preimpact anomalies were observed in the main drive system and all fractures were consistent with overload forces. The main rotor transmission remained mounted through all four intact pylon support links to the nodal beam supports. Both main rotor transmission chip detectors were removed for inspection and found to be clean with no debris. The roof structure was fractured surrounding the nodal beam supports from impact forces.
The main rotor mast assembly was rotated by hand, and continuous free movement of the main rotor transmission without binding or unusual noises was observed. The KaFlex driveshaft input assembly rotated, which confirmed main rotor drive continuity throughout the main rotor transmission. The KaFlex flexible coupling assembly remained connected to main transmission input quill. The upper portion of the main rotor mast had contact witness marks consistent with hard main rotor hub static stop contact, and the mast was bent at this location. The freewheeling unit (FWU) exhibited a fractured outer race shaft assembly (“stub” shaft) consistent with a sudden stoppage of main rotor while the engine was supplying power through its gearbox.
Rolls-Royce, M250-C30P Engine
There was no visible evidence of preimpact fire, damage, or malfunction of the engine. Both N1 and N2 turbine rotors moved continuously when rotated by hand and were smooth and quiet. The output shaft assembly, which is part of the freewheel installation, was fractured forward of its spline connection with the power takeoff gearshaft in the engine gearbox. The compressor impeller contained two blades approximately 180° apart that were heavily bent opposite the direction of rotation. Cockpit controls to the Power Turbine Governor (PTG) and Fuel control unit (FCU) were not recovered. The FCU pointer indicator was in the 100 (max) position. Both controls were checked to confirm full stop-to-stop travel of their input drive arms. Clean, clear turbine fuel was detected and drained at the inlet of the fuel spray nozzle. Primary oil supply, scavenge, vent, pressure, and torquemeter hoses were securely connected to the engine gearbox. Oil was present in the supply and scavenge hoses to the aft firewall immediately forward of the airframe oil tank and cooler compartment. Only the lower portion of the oil tank was recovered, and the oil cooler assembly was distorted from impact forces. The engine oil filter and magnetic chip detectors were clean of ferrous metal and related debris. Clean but somewhat darkened oil was observed in the engine pressure filter housing. MEDICAL AND PATHOLOGICAL INFORMATIONThe 48-year-old pilot’s aviation medical examination was on October 26, 2022. At that time, he was noted to use bilateral hearing aids. He was issued a second-class medical certificate limited by requirements to have available glasses for near vision and to use hearing amplification.
An autopsy of the pilot was performed by the Alaska State Medical Examiner, Anchorage, Alaska. According to the autopsy report, the cause of death was multiple blunt force injuries and the manner of death was accident.
A postmortem toxicological testing by the FAA Forensic Sciences Laboratory detected cetirizine at 73 ng/mL in blood and at 277 ng/g in liver tissue.
Cetirizine is a second-generation antihistamine medication that is available over the counter and is commonly used to treat allergy symptoms. Cetirizine often carries a warning that users may experience drowsiness and should be careful when driving a motor vehicle or operating machinery. Data on sedation and psychomotor impairment from cetirizine are mixed, with some studies finding some sedating and impairing effects. The FAA states that pilots should wait 48 hours after using cetirizine before flying to allow time for the drug to be cleared from circulation.