N777WN

HISTORY OF FLIGHT

On January 16, 2009, about 1300 Hawaiian standard time, an experimental Glaser-Dirks DG-400 motor-glider, N777WN, collided with mountainous terrain on the southwestern slope of Mauna Loa mountain, near Volcano, Hawaii, following an in-flight structural failure. The airline transport pilot operated the motor-glider under the provisions of Title 14 Code of Federal Regulations Part 91. The pilot was killed, and the motor-glider was destroyed. Visual meteorological conditions prevailed, and no flight plan had been filed. The flight originated at Waimea-Kohala Airport, Kamuela, Hawaii, about 1000.

A member of the Mauna Kea Soaring Club that the pilot belonged to stated that the flight was an attempt to set an altitude record. The pilot's glider had been towed to 12,600 feet mean sea level (msl) and released about 1028. Around 1245, the pilot radioed that he was in the primary wave, climbing at 1,000 feet per minute, and was at 28,000 feet (msl). He then stated that he was going to crossover to Mauna Loa. At 1644, when the pilot had not returned to Waimea-Kohala Airport at the designated time, the US Coast Guard was notified of an overdue aircraft.

On January 17th, approximately 1300, search aircraft identified debris at the 10,000-foot level, on the southwest face of Mauna Loa.

PERSONNEL INFORMATION

The pilot, age 69, held an airline transport pilot certificate for airplane multiengine land, commercial privileges for airplane single engine land, and glider, issued on May 10, 2005. He also held a flight engineer's certificate issued on July 1, 1967, and was type rated in the Boeing 737 and DC-10. An examination of his Federal Aviation Administration (FAA) medical records revealed that his most recent medical certificate was a first-class certificate issued on September 26, 1989. Flight time information was obtained from an insurance application dated April 17, 2007. The pilot reported on the insurance application that he had 15,000 hours of flight time, 812 hours in gliders, and 83.3 hours in motor-gliders.

The pilot had made a previous glider altitude record attempt on April 4, 2008, in the vicinity of the Mauna Loa Volcano, where his glider reached an altitude of 33,561 feet msl.

Friends of the pilot said that he was equipped with a finger blood oxygen sensing device. A video of the pilot’s previous record flight, on April 4, 2008, to 33,561 feet, indicates that the pilot did not put the device on until approximately 18,000 to 20,000 feet. The pulse-oximeter was not located or recovered from the wreckage. A colleague stated that he and the accident pilot had purchased the same pulse-oximeter, a “Check-Mate Pulse Oximeter.” The pulse-oximeter would be worn on a finger and displayed the person's pulse rate and blood oxygen level (SpO2). It did not have a low SpO2 warning alarm.

A parachute was not recovered with the pilot remains nor located within the glider wreckage. Colleagues stated that the pilot did not wear a parachute on this flight due to the bulk of the cold weather gear he was wearing.

AIRCRAFT INFORMATION

The single seat, retractable landing gear, motor glider (S/N) 4-116, was manufactured in 1985. The motor glider was powered by a Rotax 505, 40-horsepower engine, which retracted into the fuselage behind the cockpit when not in use. According to the members of the pilot’s soaring club, the engine had been disabled by shutting off the fuel in the engine compartment. The purpose of this was to ensure the aircraft could only operate as a glider during the altitude record attempt. The glider’s maintenance logbook recorded that the last annual inspection was performed on April 2, 2008, and the total aircraft time as recorded on July 3, 2008, was 920.9 hours. The glider’s weight and balance documentation was not located.

The glider was equipped with two oxygen systems. The Mountain High EDS (Electronic Delivery System) provides metered oxygen as the pilot inhales through a mask or cannula. The second system, which the pilot used for high altitudes, utilized a US Air Force surplus A-14 Diluter-Demand Regulator and a mask that covers the nose and mouth. With this system the percentage of oxygen delivered to the user is increased with increasing altitude, becoming 100 percent at an altitude of approximately 32,000 feet. The A-14 operating instructions state for cabin pressures below 30,000 feet the regulator pressure control knob is set to ‘normal’ and the diluter lever set at 'normal oxygen.' Between 30,000 and 40,000 feet the dial is set to 'safety,' which supplies oxygen to the mask at pressures above ambient.

Both oxygen systems were located on the right side of the cockpit. The EDS system was located at the pilot’s right shoulder and the A-14 system was located on the right just behind his head. Friends of the pilot said he operated this regulator by feel. A radio transmission from the pilot to his ground team indicated that he changed from the EDS system to the A-14 system between 28,000 and 29,000 feet. The A-14 regulator located in the wreckage was set to the ‘normal’ position.

The operating limitation section of the glider’s flight manual lists 146 knots (270 km/h) as the red line airspeed. Additionally, in the Airspeed Limits section, the flight manual states that at 20,000 feet, indicated airspeed is limited to 117 knots for flutter prevention. The provided airspeed limit table goes from 0 feet to 20,000 feet. The manufacturer stated that the airspeed limitation can be extrapolated linearly to 40,000 feet.

The flight manual states that with the cockpit loads as specified (between 154-242 lbs) the center of gravity (CG) limits will not be exceeded. The following weights were used to estimate the cockpit loads; pilot - 180 pounds, cold weather clothing – 8 lbs, two oxygen cylinders – 20 lbs. Total cockpit load was estimated to be 228 lbs.

Colleagues of the pilot stated that the fuel tank was at capacity (5.25 gallons), and that the water ballast system was not used. The flight manual states that “it is not allowed to carry water ballast” for flight at high altitudes or at low temperatures, and that in temperatures below 0 degrees C “it is possible that the control circuits could become stiffer. Special care should be taken to ensure that there is no moisture on any section of the control circuits to minimize the possibility of freeze up.”

METEOROLICAL INFORMATION

The NWS Surface Analysis Chart for 0800 on January 16, 2009, depicted the synoptic conditions over the region. The chart depicted a low pressure system with a central pressure of 947 hectopascals (hPa) south of the Alaska Peninsula with an occluded front wrapped around the low and extending southward across the eastern Pacific Ocean turning to a cold front into the northwestern Hawaiian Islands. Another developing low pressure center was identified forming north of the Hawaiian Islands near 43 degrees north latitude, with a trough of low pressure extending south-southwestward. The Hawaiian Islands were under an increasing pressure gradient from the front and was indicated by strong south to southwesterly winds across the islands, and not the prevailing tropical easterly wind flow pattern.

The 500-hPa Analysis Chart for 1400 on January 16, 2009, depicted conditions in the mean atmosphere at approximately 18,000 feet. The chart depicted the wind of 55 knots over the Hawaiian Islands with a band of maximum wind of 100 knots approximately 300 miles north of the islands.

The closest weather reporting facility to the accident site was from Bradshaw Army Airfield, Camp Pohakuloa, Hawaii, located approximately 16 miles north-northwest of the accident site, at an elevation of 6,190 feet msl. Certified military weather observers take observations daily between 0700 to 1500, and are closed during holidays. A special airport notice was listed in the Airport/Facility Directory indicated that high winds and low-level wind shear are common at the airport. The following conditions were reported surrounding the period:

Bradshaw Army Airfield weather observation at 1255 (2255Z): wind from 130 degrees at 12 knots gusting to 21 knots; visibility unrestricted at 10 miles; a few clouds at 3,000 feet, ceiling broken at 20,000 feet; temperature 18 degrees C; dew point -5 degrees C; altimeter 30.23 inches of Hg. Remarks: sea level pressure not available, wind data estimated.

The closest upper air sounding or rawinsonde observation (RAOB) was from the NWS Hilo (PHTO), Hawaii, site number 91285, located approximately 26 miles east-northeast of the accident site at an elevation of 36 feet msl. The 1200 sounding stability indices indicated a Lifted Index (LI) of 1.4, indicating a conditionally unstable atmosphere. The K-index 10 was 8.1 indicated no support for air mass type thunderstorms.

The sounding wind profile indicated surface winds from 020 degrees at 12 knots veering to the south with height through 5,000 feet, with wind speeds less than 10 knots. Above 10,000 feet the winds were from the west and increased to 43 knots at 13,000 feet and continued to veer to the northwest with height through 40,000 feet. The maximum wind was identified at 33,000 feet below the tropopause with wind from 315 degrees at 57 knots. The mean 0 to 6 kilometer (km) wind was from 266 degrees at 25 knots. At the accident airplane’s last known altitude of 38,716 feet, the wind was from 315 degrees at approximately 49 knots, with a temperature of –46 degrees C, and a relative humidity of 15 percent.

The accident site was located directly downwind of Mauna Loa, and the Hilo sounding wind and temperature profile supported mountain wave activity. The sounding produced a predominate wave at 24,500 feet or 400-hPa, with wind from 305 degrees at 41 knots, with a wavelength of 9.2 miles, an amplitude of 820 feet, and maximum vertical motion of 383 feet per minute (fpm), with a 90 percent potential of light turbulence. Moun...