National Transportation Safety Board
Aviation Accident Final Report




Molokai, HI

Accident Number:


Date & Time:

10/16/2017, 1918 HST





Aircraft Damage:


Defining Event:

Loss of control in flight


2 Fatal

Flight Conducted Under:

Part 91: General Aviation - Instructional



During a night instructional flight in the helicopter, the commercial pilot receiving instruction and the flight instructor departed and flew uneventfully to an adjacent island, where they conducted a practice instrument approach to an airport before they initiated the published missed approach procedure. As the flight reestablished radio communication with air traffic control, the pilots obtained an instrument flight rules clearance for their return to the departure airport. Radar and radio contact with the helicopter were lost shortly thereafter. Air units from the United States Coast Guard and a local fire department located some floating debris in the ocean the night of the accident and the day following the accident, respectively. The wreckage was located about 12 months following the accident submerged in the Pacific Ocean at a reported depth of 298 ft. A portion of the located wreckage was recovered about 3 months later. A postaccident examination of the recovered wreckage revealed no evidence of any preexisting mechanical malfunctions that would have precluded normal operation of the airframe or engine.

Weather radar depicted an area of moderate-to-heavy rain showers along the helicopter's flight path about the time radar and radio contact were lost. Although the pilots had access to sufficient weather information to properly plan their flight around the weather and could have asked for further assistance in avoiding the weather from air traffic control, they elected to fly into an environment favorable to unexpected changes in wind direction and speed due to heavy rain showers, which could result in localized instrument meteorological conditions; however, because only a portion of the wreckage was recovered, the reason for the helicopter's sudden descent and impact with open ocean waters could not be determined.


Probable Cause and Findings

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

A descent and subsequent impact with open ocean waters for reasons that could not be determined based on the available information.




Not determined

Not determined - Unknown/Not determined (Cause)

Factual Information

History of Flight

Enroute-change of cruise level

Loss of control in flight (Defining event)

Collision with terr/obj (non-CFIT)


On October 16, 2017, about 1918 Hawaii-Aleutian standard time, a Robinson Helicopter R44, N820DF, impacted the Pacific Ocean near Molokai, Hawaii. The flight instructor and commercial pilot receiving instruction are missing and presumed to be fatally injured. The helicopter was registered to Stasys Aviation Leasing LLC and was being operated by Hawaii Pacific Aviation, doing business as Mauna Loa Helicopters, as a Title 14 Code of Federal Regulations Part 91 instructional flight. Instrument and visual meteorological conditions existed in the area around the time of the accident, and an instrument flight rules (IFR) flight plan was filed for the flight, which originated from Daniel K. Inouye International Airport (PHNL), Honolulu, Hawaii, at an undetermined time.

Information provided by the Federal Aviation Administration (FAA) indicated that air traffic control (ATC) cleared the flight for a practice RNAV (GPS)-B instrument approach to the Molokai Airport (PHMK), at which time the pilots requested a pop-up IFR clearance to PHNL. The controller instructed the pilots to depart via the published missed approach to 4,000 ft, and expect clearance on departure, which the pilots acknowledged. The controller subsequently terminated radar service, approved a frequency change, and informed the flight to return to that frequency after conducting the missed approach.

The flight executed the missed approach as instructed and reestablished radio contact with ATC about 1 mile north of PHMK as it was climbing through 1,700 ft. The controller radar-identified the helicopter and subsequently issued a clearance to PHNL with instructions to fly a heading of 260° and climb to 4,000 ft. About 4 minutes later, the controller issued a heading change to 240° to intercept the Victor 8 airway; the pilots acknowledged. About 2 minutes later, the controller advised the flight that radar contact with the helicopter was lost. No further radio transmissions were received from the pilots.

Radar data showed that the flight's radar track started about 1.3 nautical miles (nm) northeast of PHMK and remained on a north-northeasterly heading while climbing from 1,700 ft to 3,500 ft msl for about 3 minutes. The helicopter then entered a left turn to a westerly heading while continuing a climb to 4,000 ft msl. The track continued on a westerly heading for about 2 more minutes before it began a right turn to an east-southeasterly heading. About 35 seconds later, the helicopter entered a left turn to a northwesterly heading and began descending from 4,000 ft msl to 3,700 ft msl over about 35 seconds. Shortly thereafter, the track continued in a left turn to a southeasterly heading for about 19 seconds while climbing to 3,900 ft. The helicopter then turned to a westerly heading and had descended to about 2,700 ft when radar contact was lost about 6 miles northwest of PHMK.

A representative from the United States Coast Guard reported that, after the helicopter was reported missing, an air unit located debris and a red chemlight floating in the ocean northwest of Molokai. The following day, an air unit from the Maui Fire Department located an uninflated life jacket along the northwest shoreline of Molokai. The search for the helicopter was suspended on the evening of October 19, 2017. Reported water depths in the vicinity of the last radar target varied between 348 ft and 1,812 ft.


Flight Instructor

The flight instructor, age 24, held a commercial pilot certificate with rotorcraft-helicopter and instrument helicopter ratings. In addition, he held a flight instructor certificate with rotorcraft-helicopter and instrument-helicopter ratings. The flight instructor was issued a second-class FAA medical certificate on January 5, 2017, with the limitation, "must wear corrective lenses." On the application for that medical certificate, the flight instructor reported a total flight experience of 630 hours, of which 300 hours were in the previous 6 months.

Pilot Receiving Instruction

The pilot receiving instruction, age 27, held a commercial pilot certificate with a rotorcraft-helicopter rating. He held a second-class FAA airman medical certificate that was issued on June 2, 2017, with the limitation, "must wear corrective lenses." On the application for that medical certificate, the pilot reported a total flight experience of 139 hours.

Review of the pilot's flight training records revealed that, as of the most recent entry, dated October 12, 2017, he had accumulated a total of 186.9 hours of flight experience, of which 18.5 hours were in the previous 30 days.


The accident helicopter was a Robinson R44 II, four-place, two-bladed, single main rotor, single-engine helicopter with skid-type landing gear. The primary structure was welded steel tubing and riveted aluminum. The tailboom was a semi-monocoque structure consisting of an aluminum skin. The helicopter was equipped with a Lycoming IO-540-F1B5 engine, rated at 260 horsepower; however, according to the helicopter's type certificate, the de-rated engine had a 5-minute takeoff rating of 245 horsepower and a maximum continuous rating of 205 horsepower. The helicopter was certified for day and night visual flight rules operations only.

Review of the airframe and engine logbooks revealed that the most recent annual inspection was completed on September 28, 2017, at an airframe total time of 4,209 hours and an engine total time since major overhaul of 2,009.2 hours.


At 1854, the recorded weather conditions at PHMK, located 6.3 miles southeast of the last radar target, included wind from 030° at 8 knots gusting to 21 knots, 10 statute miles visibility, light rain, few clouds at 3,300 ft above ground level (agl), a broken cloud ceiling at 6,000 ft agl, a broken cloud layer at 7,000 ft agl, temperature 24°C, dew point 20°C, and an altimeter setting of 30.04 inches of mercury.

The closest National Weather Service (NWS) Weather Surveillance Radar-1988, Doppler (WSR-88D) to the accident site was the Molokai, Hawaii, radar (PHMO), which was located 6 nm south-southwest of the accident site at an elevation of 1,363 ft. The WSR-88D captured base reflectivity imagery at 1917 and 1918 (shown in figures 1 and 2, respectively; the black line shows the helicopter's flight path). The imagery depicts moderate-to-heavy values of reflectivity within the vicinity of the last radar target. Rain showers and convective clouds produce outflow boundaries and gust fronts throughout their life cycle. An outflow boundary or gust front can create an environment favorable for unexpected changes in wind direction and speed. There were no lightning strikes in the vicinity of the last radar target around the time of the accident.

Figure 1: WSR-88D base reflectivity imagery at 1917