WPR17FA021

The pilot's decision to continue visual flight into an area of instrument meteorological conditions at night in rain, which resulted in his geographic disorientation and controlled flight into terrain.

The airline transport pilot and passenger departed on an expected 30-minute visual flight rules flight that was destined for the pilot's private helipad and residence on the southeast side of a neighboring Hawaiian island. Before the flight, the pilot's mechanic asked the pilot not to fly due to the weather at the intended destination, but the pilot insisted on flying. The National Weather Service forecast products that were available before the flight indicated a trade wind pattern that would bring bands of rain, low visibility, and mountain obscurations to the eastern slopes of the islands, but it is unknown if the pilot reviewed these products or any other forecast of expected weather conditions along the flight route. One witness stated that the pilot routinely flew at night to his helipad and that she had previously seen the pilot's helicopter operating in dark adverse weather conditions. Several witnesses reported seeing the helicopter fly over their locations in dark conditions with wind and rain. Two witnesses reported that they saw the helicopter make an approach to a ridgeline near the pilot's helipad, but then the helicopter disappeared from view because of a cloud or terrain. Meteorological data revealed that a line of rain showers moved over the accident site at the accident time. The reduced visibility and ceiling as the line of rain showers moved east to west over the rising mountain terrain likely resulted in instrument meteorological conditions and mountain obscuration conditions.  The helicopter wreckage was discovered 0.75 mile upslope of the intended destination. Tree and ground impact marks indicated a relatively level descent to the ground at an approach angle of about 18° on a 310° heading, which is indicative of impact with terrain in controlled forward flight. The helicopter was destroyed by impact forces and a postcrash fire. Examination of the wreckage revealed no evidence of any preimpact failures or malfunctions of the engine, drive train, main rotor, tail rotor, or structure of the helicopter. Damage to the mast support structure, main rotor hub, main rotor blades and upper flight controls is consistent with power-on main rotor blade impact damage. Given the weather conditions and witness observations, the pilot encountered dark instrument meteorological conditions and rain while flying in an area of rising terrain as he likely searched for the helipad at his residence, which was outfitted with various lights that would have been difficult to see in reduced visibility. The pilot did not have the visual cues necessary to maintain clearance above the ground, resulting in geographic disorientation, which subsequently led to controlled flight into terrain.

The National Weather Service (NWS) area forecast for Hawaii, issued at 1734 and valid at the time of the accident, indicated the following conditions for Oahu and Molokai: scattered clouds at 2,500 ft, scattered to broken ceiling at 5,000 ft; temporary conditions of broken ceilings at 2,500 ft and visibility between 3 and 5 miles with rain showers; and isolated conditions of broken ceilings at 1,500 feet with visibility below 3 miles in rain showers. The NWS area forecast discussion (AFD) at 1604 (the closest AFD to the accident time) indicated that an area of showery low clouds was moving toward the islands in the trade wind flow (west) and was expected to continue to promote the development of marginal VFR conditions (visibilities and ceilings) over windward (east) portions of the Big Island…and appear poised to move ashore over windward portions of the smaller islands (Molokai) overnight. AIRMET Sierra was issued at 1731, before the flight departed, and was valid at the accident time and for the area near the accident site. AIRMET Sierra advised of mountain obscuration on the north- through east-facing slopes of Molokai due to clouds and rain. The closest official weather station to the accident site was an automated surface observing system (ASOS) at MKK, which was about 17 miles west of the accident site. The ASOS recorded the following conditions at 1854 (13 minutes after the accident): wind from 030° at 15 knots with gusts to 21 knots, visibility 10 miles, a broken ceiling at 4,800 ft, a broken cloud layer at 5,500 ft, temperature 24°C, dew point 21°C, and altimeter 30.04 inches of mercury. The surface observations surrounding the accident time indicated VFR conditions on the leeward side of mountainous terrain with periods of rain and gusty wind from the east to the northeast. A review of archived radar data from the Molokai NWS Weather Surveillance Radar-1988, Doppler (WSR-88D,) which was located 17 miles west of the accident site, showed that, between 1834 and 1845, a line of rain showers moved from east to west over the accident site, likely with reduced visibilities and ceilings. Figure 2. WSR-88D Doppler Radar at 1840. A search of official weather briefing sources, such as Lockheed Martin Flight Service and Direct User Access Terminal Service, indicated that the accident pilot did not request an official weather briefing. The pilot's mechanic stated that the pilot normally checked the Molokai radar images on the NWS website before his flights to Pukoo. According the US Naval Observatory astronomical data, sunset at the accident site on the day of the accident was at 1746, and the end of civil twilight was at 1809. The moon was not visible during the accident flight; moonrise occurred at 1925. For further weather information, see the weather study in the public docket for this accident. The pilot, age 70, held an airline transport pilot certificate with a rotorcraft-helicopter rating issued on December 29, 2009. Additionally, he held a commercial pilot certificate with airplane multiengine land and instrument airplane ratings and a private pilot certificate with an airplane single-engine land and sea rating. His most recent FAA third-class medical certificate was issued on May 17, 2016, with the limitation to have available glasses for near vision. According to a family member, the pilot was in excellent health. On his most recent medical certificate application, the pilot reported 4,210.7 hours of total flight experience, 45.2 hours of which were within the last 6 months. The pilot's logbook was not located, so his instrument and night flight experience and the number of hours in the accident helicopter make and model could not be determined. According to the pilot's workplace personal assistant, the pilot flew to Molokai about every other week, often after work at night. A family member recalled that, during one flight, the pilot diverted to MKK due to deteriorating weather conditions near Pukoo. The family member also stated that the pilot used GPS to navigate at night. The helicopter, serial number 100634D, was manufactured in 1979 as a Hughes 369D helicopter. The type certificate at the time of the accident was held by MD Helicopters, Inc. (MDHI) The helicopter was powered by a Rolls-Royce (Allison) 250-C20B turboshaft engine. The helicopter was controlled by a single pilot from the left seat. The helicopter's maintenance records revealed that its last annual inspection occurred on September 17, 2016. According to a maintenance tracking report dated November 17, 2016, the airframe total time was 9,640.1 hours, and the engine total time was 8,371.1 hours. An emergency locator transmitter was not installed or required to be installed. The accident site was located on the southeast side of Kamakou Mountain, which has a peak of 4,970 ft, in a remote area on a 25° southeast slope of a rising ridge at 1,389 ft. The wreckage came to rest about 0.75 mile north of the helipad at the pilot's residence. An aerial view of the wreckage site indicated a confined wreckage field, about 80 ft long and 25 ft wide, of burned and fragmented components on a heading of about 310° and a ground brush fire pattern that continued northwest for 50 ft upslope. Postimpact fire damage was observed throughout the wreckage field. All major components were found. Tree strike marks and broken tree limbs were observed on the south end of the wreckage field, starting at tree tops located about 100 ft from the initial ground impact. The tree strikes indicated a descent angle of about 18° from the tree tops to the landing skids, which made the first ground impact. The transmission, main rotor head, rotor blades, engine, and tail rotor drive shaft were spread upslope through the burned area and showed thermal and impact damage. The tail rotor section was found intact near the southwest portion of the site. No thermal damage was observed, but the tail rotor section was completely fractured forward of the tail rotor gear box. The landing skid tubes had separated from the airframe and were located at the southern end of the wreckage field among broken canopy windscreen pieces. The left skid was imbedded almost 30 inches into the dirt, consistent with forward flight and the initial impact point. The fuselage and cockpit sustained extensive thermal damage with only the engine firewall intact. The cabin and cockpit were completely consumed by the postimpact fire, but a few instruments were recovered at the scene. The altimeter indicated 913 ft with a setting of 30.00 inches of mercury. The dual tachometer gauge was found on the ground with an NR (rotor speed) reading of 340 rpm and an N2 power turbine speed reading of 78 percent. The pilot's cyclic grip was fractured and separated from the control stick about 1 inch below the grip, with wires from the switches extending outward from the fracture. The GPS unit was not located. The pilot's watch was recovered at the scene; the pointers had stopped when the time was 1841. The support structure with the mast, main transmission, upper controls, main rotor hub, and five main rotor blades separated from the main fuselage near the upper fuselage attach areas. Two of the five main rotor blades remained attached to the main rotor hub; the others had separated at the steel strap sets and were found near the rotor head. Each main rotor blade showed signs of impact damage, bending, span-wise splitting along bond joints, and thermal damage. Two of the five blade tips were located. Damage to the mast support structure, main rotor hub, main rotor blades and upper flight controls is consistent with power-on main rotor blade impact damage. The aft section of the tailboom, which consisted of the vertical and horizontal stabilizer, tail rotor gearbox, and the tail rotor assembly, had separated from the rest of the tailboom. A long section of the tail rotor drive shaft was found near the c