Pilot Was Going For Altitude Record
A well-known glider pilot, David
Bigelow (69), lost his life last year while flying Hawaii's amazing
mountain wave action in pursuit of an altitude record. Bigelow was
a highly-experienced flyer, and a retired Air Force captain, as
well as a former commercial airline pilot and member of the Mauna
Kea Soaring Club. Bigelow's flight that was an attempt to set an
altitude record, and was not his first such effort -- in April
2008, Bigelow had ascended to an absolute altitude of 33,561 feet.
During the January 2009 attempt, the aircraft reached an ultimate
altitude of 38,630 feet but broke up in flight, killing
Bigelow.
The NTSB's report, released over the weekend 'determines the
probable cause(s) of this accident as follows: The pilot's loss of
pitch control and subsequent exceedance of the glider's airspeed
limit for undetermined reasons.'
Full NTSB Report -- WPR09FA089
HISTORY OF THE 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.
File Photo-Glaser Dirks
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.”
File Photo-Glaser Dirks
METEOROLIGICAL 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. Mountain wave activity
severity is dependent on wind speed, stability, mountain height,
and slope steepness. Modifying the program for slope steepness with
a half mountain width of 4 miles, created a predominate wave at
25,760 feet with a wavelength of 9.2 miles, amplitude of 629 feet,
maximum vertical motion of 2,938 fpm, and capable of produced
severe turbulence. The RAOB default mountain wave program
variables, which produces the maximum potential mountain wave
amplitude by using a 1 kilometer high (3,280 feet) mountain and a
half width automatically adjusted to the natural wavelength of the
air stream also produced a moderate to severe wave at approximately
25,000 and 29,000 feet. No waves were detected between 32,000 and
40,000 feet.
The Geostationary Operations Environmental Satellite number 11
(GOES-11) data was obtained from the National Climatic Data Center
(NCDC) and displayed on the National Transportation Safety
Board’s Man-computer Interactive Data Access System (McIDAS)
workstation. The GOES-11 visible (band 1) image at 1230, 1300, and
1330 respectively, at 2X magnification, the image depicted clear
skies over the accident site. The images depict the peak of Mauna
Loa to the west and Mauna Kea to the north both covered in snow.
Low stratus and stratocumulus clouds were over the northern and
western portions of the island, north of the departure airport of
Waimea-Kohala over the Kohala Mountains and over Kona International
Airport. An arch of stratocumulus type clouds is observed over the
northeast part of the island in the leeside flow of Mauna Kea. A
band or line of stratocumulus clouds or specifically vortex streets
are observed directly east of the island downwind indicating some
blocking of the wind from the mountains across the island.
The Regional Atmospheric Soaring Prediction (RASP) model data
over the Hawaiian Islands was obtained for the period. The RASP is
a high-resolution (1-12 kilometer) meteorological forecast designed
to help soaring pilots plan their flights. These high resolution
charts are particularly useful for those locations where soaring
conditions can vary dramatically over short distances, as in or
near complex terrain. Forecasting terrain-forced phenomena, such as
terrain-channeled winds and terrain-induced convergence, requires
that the terrain to be resolved and RASP is capable of providing
finer-scale resolution than most National Center for Environmental
Prediction (NCEP) models. The accident pilot experimented with RASP
model charts along with other model data for planning his flights,
along with other official NWS data.
Multiple pilot reports northwest of Hilo from flight crews
operating a Canadian Regional Jets (CRJ2) reported moderate
turbulence between 7,000 and 13,000 feet during their climb. The
cruising level of flight level was not identified. Another glider
pilot who was operating in the Mauna Kea area surrounding the
period (also in contact with the accident airplane) indicated that
he encountered smooth conditions until he descended below 5,000
feet.
The Area Forecast (FA) is an aviation forecast of general
weather conditions over an area the size of several states. It is
used to determine forecast en route weather and to interpolate
conditions at airports that do not have Terminal Aerodrome
Forecasts (TAFs) issued. The NWS Honolulu office issued the area
forecast at 1203, and was valid until 2400 local. The forecast for
the big Island of Hawaii interior above 7,000 feet was for a few
clouds at 9,000 feet with temporarily surface winds over the
mountain ridges west-to-northwest at 25 to 35 knots, with higher
gusts to 60 knots with isolated broken clouds at 9,000 feet with
tops to 10,000 feet.
The NWS issues in-flight weather advisories for Hawaii
designated as SIGMET's (WS's), and AIRMET's (WA's) serve to notify
en route pilots of the possibility of encountering hazardous flying
conditions, which may not have been forecast at the time of the
preflight briefing. The forecast available to the pilot of N777WN
prior to his departure was issued at 0545 and valid until 1200. The
advisories did not expect any significant IFR or icing conditions
across the Hawaiian Islands, occasional moderate turbulence was
expected below 10,000 feet with conditions expected to continue
beyond 1200. The outlook beyond 1200 from Kauai though Maui
expected sustained surface winds greater than 20 knots due to the
approaching cold front. The next schedule AIRMETs were issued at
1145 and were valid until 1800, and expected the same conditions to
continue through the period.
The complete Meteorological Factual Report is available in the
official docket of this investigation.
File Photo-Glaser Dirks
FLIGHT RECORDERS
The pilot had equipped the gilder with an EW Avionics
microRecorder that was used to document the aircraft flight
utilizing GPS technology, and a Sony HDR-TG1 high definition (HD)
video/audio recorder. The EW Avionics mircroRecorder was
continuously recording data throughout the flight. The video
recorder was used by the pilot as a video diary, where the pilot
would turn it on to make some commentary then turn it off.
EW Avionics microRecorder
The EW Avionics microRecorder is a GPS-based flight recorder
capable of logging a GPS track, engine noise measurement, and
barometric pressure altitude in a secure .IGC file. The flight
recorder is battery-operated using internal rechargeable batteries
and can operate for up to 100 hours on a single charge. Data is
stored in non-volatile FLASH memory. Logging intervals are
adjustable from 1 to 10 updates per second. Logged data is
continuously recorded up to the internal memory limit, after which
the oldest data is replaced with new data on a first-in-first-out
basis.
The data recovered from FLASH memory was data-mined using
standard hex editing software and stored IGC data corresponding to
the accident flight was identified.
Recovered data included the following parameters for each
recorded (logged) data point: latitude/longitude position at the
time of the update; fix validity; pressure altitude; GPS Altitude;
fix validity; number of satellites in view; ground speed; and
engine noise measurement. The engine noise measurement parameter is
facilitated by a microphone that records cockpit noise.
Data corresponding to a logged flight dated January 16, 2009,
began at 0902:51 with a latitude/longitude position fix
corresponding to Waimea-Kohala Airport. The glider took off from
Waimea-Kohala and flew south-southwest to ride lift that was near
the mountains behind the town of Holualoa. The flight then
proceeded east-northeast to ride the lift up again over Mauna Kea.
The flight then proceeded south-southwest to rise up over Mauna
Loa, where the flight abruptly ended with a rapid descent almost
directly down. The final 20 minutes of the flight shows the glider
entering the area from the north and making one s-turn searching
for lift before proceeding a short distance further. The glider
began s-turning upwind, then turned back to the north. After flying
a short distance, the glider began exploring the area just downwind
of Steaming Cone, making one left 360, followed by a right 360. The
glider began to make a second right 360 when the rapid descent
ensued. The recording ended approximately 1 minute later. The
glider reached a maximum pressure altitude of 36,846 ft (38,716 ft
GPS derived altitude), at 1314:59; about 1 minute 40 seconds before
the end of the recording. During the last 3 minutes 20 seconds of
recorded data the ground speed is seen to begin rapidly varying
between about 75 mph and 150 mph with a period of about 10 seconds.
After the first cycle the GPS altitude begins to decrease, and
after about 2 ½ cycles the ground speed begins to drop
dramatically. At 1315:47, the ground speed levels off at about 20
mph with a GPS altitude of 31,439 ft. The recording ended 42
seconds later at a GPS altitude of 11,825 ft; an equivalent descent
rate of about 28,000 fpm.
A plot of the glider’s track during the last 6 minutes of
the recording illustrates large radius curves consistent with
controlled constant rate turns. Three minutes and twelve seconds
from the end of the recording, at 38,630 feet, the track abruptly
becomes linear, heading in a southwest direction, and the rate of
descent rapidly increases over the next 16 seconds to 24,000 feet
per minute. Fifty-six seconds from the end of the recording the
track suddenly reverses course approximately 180 degrees, and
descends almost vertically until the end of the data.
The true airspeed of the glider can be estimated using the
ground speed provided by the microRecorder datalogger, and
calculating the rate of descent using the altitude recorded at
4-second intervals. Wind affects can be disregarded because the
southwest track that is being examined is perpendicular to the
prevailing winds of 315 degrees at 38,715 feet, effectively
eliminating headwind or tailwind components. The true airspeed was
calculated using simple trigonometric functions as the resultant
vector between the rate of descent and ground speed. Between
1315:23 and 1315:43, the true airspeed is calculated at 4-second
intervals to increase from 60 knots, to 120 knots, 103 knots, 180
knots, and finally 241 knots.
File Photo-Glaser Dirks
HDR-TG1 Video Recorder
The Sony HDR-TG1 is a High Definition (HD) digital video
recorder capable of recording video at full 1920 x 1080 HD
resolution. The video recorder was damaged beyond repair due to
impact forces. A 4GB memory stick was found within the unit. The
memory stick showed signs of minimal damage and was readable using
a standard card reader attached to a PC. Nine MTS (MPEG Transport
Stream) files were recovered from the memory stick. These files
were named 00000.MTS through 00008.MTS. These files were converted
to the WMV (Windows Media Video) standard and viewed on a standard
PC running MS Windows.
The video files recovered represented segments of the accident
flight covering the period from just prior to takeoff to about 52
minutes prior to the time of the accident. For every file, the
video captured a view directly forward from a position near the
pilot’s head, showing a wide-angle view of the external
environment. The pilot’s knees were just visible in the
bottom of the view. None of the cockpit instruments were visible
and no other part of the pilot was visible.
File 00000.MTS, 1001:04-1003:20, glider takes off from
runway.
File00001.MTS, 1020:36-1027:59, pilot reported reaching 10,000
feet, stated that the winds aloft were 227 degrees at 30 knots,
released the tow line, and made a left turn.
File 00002.MTS, unknown, 4-second snippet.
File 00003.MTS, 1032:21-1036:44, pilot stated he is in a wave at
13,300 feet and climbing. Sounds consistent with supplemental
oxygen use were recorded.
File 00004.MTS, 1052:47-1055:40, pilot reported a
300-foot-per-minute (fpm) rate of climb, winds aloft of 282 degrees
at 48 knots. At 1054:27, another glider made a radio call
announcing their approach to 20,000 feet. At 1055:10, pilot stated
he’s passing 14,000 feet at 300 fpm.
File 00005.MTS, 1125:25-1128:07, pilot states he’s passing
17,000 feet in weak lift. At 1125:55, he reported that the oxygen
is on, and his blood saturation was about 90 (%). At 1126:31, the
pilot reported winds aloft of 290 degrees at 44 knots. Sounds
consistent with supplemental oxygen use were recorded.
File 00006.MTS, 1159:09-1201:34, pilot stated he as at the top
of the Hualalai wave at 20,700 feet. At 1159:47, he reported his
blood oxygen is 89(%). At 1201:34, the pilot radioed that he is
starting to head towards Mauna Kea. Sounds consistent with
supplemental oxygen use were recorded.
File 00007.MTS, 1211:58-1217:37, the pilot stated he’s
close to Mauna Kea at 18,800 feet. At 1215:47, the pilot made a
radio call reporting that he was in lift passing through 17,000
feet at 400 fpm. At 1217:01, the pilot stated the pressure of the
first oxygen bottle was 1,000 (psi), blood oxygen is 93 (%). Sounds
consistent with supplemental oxygen use were recorded.
File 00008.MTS, 1222:05-1223:32, the pilot stated he was passing
20,000 feet at 800-900 fpm. At 1223:32, the pilot reported he is at
21,000 feet. Sounds consistent with supplemental oxygen use were
recorded.
No further recordings were made after 1223:32.
The entire GPS Factual Report and the Digital Video Factual
Report are contained in the official docket of this accident
investigation.
WRECKAGE AND IMPACT INFORMATION
The wreckage was located on the southeastern slope of Mauna
Loa on a steep slope of barren lava rock.
The glider was retrieved by Hawaii Volcanoes National Park
rangers. They reported a Plexiglas debris field near the fuselage
wreckage. The canopy emergency release knob was found in the stowed
position; it appeared to not have been activated. The left wing was
severely damaged from its root outboard for approximately 5 feet,
and was located 3.44 miles southeast of the main wreckage. The
remaining outboard wing section appeared relatively undamaged and
the spoiler moved freely. Its detachable one meter tip extension
appeared almost undamaged; its I-beam spar extension, which was
used for assembly, appeared damaged. The right wing was located
with the main wreckage, was badly damaged and fractured in pieces.
Its spoiler extension tubes were not damaged, but the spoiler
itself was bent and deformed, and is consistent with damage as a
result of ground impact forces. The right wing’s one meter
detachable tip extension appeared undamaged. Its I-beam spar
extension appeared undamaged. During the wreckage examination, both
detachable tip extensions were found detached. The horizontal
stabilizer and elevator control surfaces were not located or
identified during the examination.
Examination of the wing spar carry though revealed that the left
wing bottom spar cap fracture surface exhibited a flat face, and
carbon fibers that were bent and buckled in a manner consistent
with compression loading. The upper spar cap fracture surface was
jagged with carbon fiber ends extending at different lengths,
consistent with tension loading.
The cockpit, fuselage, and empennage were shattered into
unrecognizable pieces. A lap belt tongue and shoulder belt tongue
remained engaged in the seat harness rotary buckle. The A-14 oxygen
regulator knob was set at ‘normal.’
MEDICAL AND PATHOLOGICAL INFORMATION
An autopsy was performed on the pilot on January 20, 2009, at
the Hilo Medical Center, by the Department of Pathology, Hilo,
Hawaii. The autopsy findings state that the immediate cause of
death was multiple traumatic injuries.
Forensic toxicology was performed on specimens from the pilot by
the FAA Forensic Toxicology Research Team CAMI, Oklahoma City,
Oklahoma. The toxicology report stated no ethanol was detected in
muscle or lung tissue, and none of the listed drugs were detected
in muscle tissue.
ADDITIONAL INFORMATION
According to a recent textbook on aviation medicine, “When
an altitude of about 39,000 feet is reached, breathing 100 percent
oxygen, the alveolar oxygen tension falls to … a similar
value to that reached at 10,000 feet when breathing air.”
(Gradwell, DP. Hypoxia and Hyperventilation, in Ernsting’s
Aviation Medicine, Fourth Edition (Eds. D.P. Gradwell and D.J.
Rainford), Edward Arnold, London, 2006, p. 45).
Data from the Hilo airport surveillance radar (ASR) for the 30
minutes prior to the accident was reviewed. No traffic was
identified as being in the vicinity of the glider prior to the
accident.