The probable cause for
a somewhat unusual Cirrus SR22 accident last December has just been
determined by the NTSB. Involved in a loose formation with a
motor-glider, the Cirrus SR22 eventually stalled and impacted
mountainous terrain in Montana. Despite several rumors and some
post-crash reports by persons not associated with the NTSB, the
aircraft was functioning normally at the time of the crash and the
aircraft experienced no loss of power. Pilot error was ultimately
cited as the cause of the accident, which klilled three.
NTSB Report
On December 4, 2004, approximately 1530 mountain standard time,
a Cirrus SR22 airplane, N1159C, impacted mountainous terrain while
maneuvering about 10 nautical miles northeast of Belgrade, Montana.
The commercial pilot and two of the three passengers were killed.
The other passenger received serious injuries. The airplane, which
was registered to Flightline Fractionals Inc. and operated by the
pilot, was destroyed. The local personal flight was conducted under
14 CFR Part 91. Visual meteorological conditions prevailed, and no
flight plan was filed. The airplane departed from Gallatin Field
Airport, Belgrade, Montana, at 1518.
At the time of the accident, a motor glider was flying near the
area where the accident occurred. The pilot of the motor glider was
interviewed by the NTSB investigator-in-charge and reported that he
was giving a ride to a friend of the pilot of the accident
airplane. Prior to departing from Gallatin Field, the motor glider
pilot spoke with the pilot of the accident airplane, who told him
that he would get the airplane out, takeoff, catch up with the
glider and make some "flybys" of the glider. The motor glider pilot
said that after takeoff, he remained on the tower frequency and
heard the airplane depart. The pilots of both aircraft then tuned
their radios to an air-to-air frequency and established
communications.
The motor glider had shut down and stowed his engine and was
soaring north along the western edge of the Bridger mountain range
nearing Sacagawea Peak. The airplane made one pass above the
glider, circled and made a second pass immediately to the left of
the glider. When the airplane passed by the glider, it was "in
coordinated flight," with the flaps up, and it was either flying
level or descending slightly. The glider pilot watched the airplane
continue heading north "straight out in front of him" for about 5
to 10 seconds. Since the glider was losing lift, he then made a
turn to the south.
At the time the glider pilot last saw the airplane, it was
heading towards a transverse "foothills ridge" that runs downward
from the summit of Sacagawea Peak (elevation about 9,600 feet)
towards the west and then hooks toward the south. There is a peak
(elevation about 8,916 feet) on the transverse ridge at the point
where it hooks south. According to the glider pilot, this ridge is
unique compared to the rest of the transverse ridges coming off the
crest of the Bridgers in that it "does not fall away like the rest
of the foothills." The combination of the crest of the Bridger
range and this transverse ridge form a cirque or bowl that is open
to the south and has high terrain to the west, north and east.
After gaining altitude, the glider pilot turned back to the
north. He then saw a column of black smoke, which was later
identified as being from the crash site. The column of smoke was
located just south of the 8,916-foot-peak on the transverse ridge.
It was 5 minutes between the time the glider pilot last saw the
airplane and the time he turned back north and spotted the smoke.
The glider pilot reported that the weather was clear blue sky, no
turbulence, "no sucking downdrafts," but some "down air" in the
area where he last saw the airplane.
The glider pilot analyzed the data recorded in the glider's
flight logger for his flight on the day of the accident. His
analysis indicated that when the airplane passed the glider on its
second pass, the glider was at an altitude of about 8,900 feet, had
a ground speed of about 57 knots, and the time was about 1529:30.
About 90 seconds later, he made his turn back to the south. When he
made the turn, he was about 500 yards from the crash site, at
altitudes between 9,100 and 9,200 feet, in the bowl formed by the
crest of the Bridgers and the transverse ridge. During the turn, he
encountered an air mass that was sinking about 100 to 200 feet per
minute, and the glider lost about 50 feet of altitude.
The surviving passenger was interviewed on December 15, 2004, by
the NTSB investigator-in-charge (IIC) and an FAA inspector. The
passenger was not a rated pilot or aircraft mechanic, but had
gotten involved in working on airplanes when he was in high school.
He explained that he flew frequently with different pilots at the
airport "when he got the chance." This was his first flight in a
Cirrus and his first flight with the pilot. The passenger reported
that he was seated in the left rear seat and that all four
occupants had headsets on, and they could talk with each other and
also hear the transmissions on the airplane's communication radio.
He further reported that there were no problems with the airplane
during the run up or takeoff. After departing the airport, they
headed directly towards the mountains to meet the glider. When they
spotted the glider, it was considerably to their left. They crossed
behind the glider at its altitude, continued over the crest of the
Bridgers and made a "big swooping left turn." They crossed back
over the crest of the Bridgers and passed in front of and above the
glider. They "had a smooth ride the whole flight. There was very
little wind shear even when they crossed over the ridge crest."
According to the surviving passenger, the pilot leveled out the
airplane, and they turned back to the right to get behind the
glider. They were climbing "to bleed off speed." The passenger
could not see the glider as they were still in a right bank, and to
see the glider, he would have had to be able to see through the
roof of the airplane. The airplane was positioned behind and left
of the glider, and it was "in a light climb." The stall warning
indicator came on in the airplane. When this happened, there was no
discussion about it between the pilot and the right front seat
passenger, who was also a pilot. The surviving passenger heard the
engine pick up speed. The stall warning continued to buzz. The
third passenger, who was seated in the right rear seat and who was
also a pilot, said, "isn't that your stall buzzer?" and the pilot
replied, "yeah." The pilot dropped the nose to level out, and the
stall warning indicator stopped sounding. The passenger heard a
noise that sounded like the flaps were going down. He looked out
and saw that the flaps were not moving. He could not see the pilot
moving the flap control; he just heard the noise, there was no
conversation about it. The sound he heard was a high-pitched whine,
and it sounded like what he had heard during the preflight
check.
The passenger stated that the left wing dropped and they
"started going down hill. It felt like what had happened before
during the flight as they turned to stay with the glider. It felt
like the airplane was under control." The pilot turned and said,
"hang on, we might get a couple of trees on this one." The pilot's
tone of voice was "totally normal." At this point, the nose was
"somewhat up," the passenger was looking forward, and he could not
see trees. It was about 10 to 15 seconds from the time the stall
warning horn stopped sounding until they hit the trees. He heard a
few bumps like the landing gear was hitting something. Then they
hit something hard and he was "slung way forward." His next
recollection was waking up laying on bare ground.
AIRCRAFT INFORMATION
Examination of the airplane's maintenance records indicated that
the airplane was manufactured in 2003 and received its most recent
annual inspection on November 24, 2004, at a total airframe time of
388.3 hours. As of that date, the engine, a Continental IO-550N7B,
S/N 686803, had accumulated 388.3 hours since new. Review of the
maintenance records revealed no evidence of any uncorrected
maintenance discrepancies.
According to the pilot who flew the airplane just prior to the
accident flight, she experienced no problems with the airplane
during her 1.2 to 1.3 hour flight. She stated that the flaps worked
normally during the four takeoffs and landings she made during her
flight. She estimated that the airplane had 28 to 30 gallons of
fuel remaining at the conclusion of her flight.
The weight and balance of the airplane at takeoff was estimated
using the following information: basic empty weight 2,353 pounds,
front seat occupants 375 pounds, rear seat occupants 296 pounds,
baggage 10 pounds, fuel 180 pounds (30 gallons). The estimated
takeoff weight was 3,205 pounds, which was below the maximum
takeoff weight of 3,400 pounds. The estimated takeoff moment was
464.276/1000 (pound-inches/1000), which was within the allowable
moment range for the calculated takeoff weight. (At 3,200 pounds,
the allowable moment range is 452/1000 to 474/1000.)
According to the Pilot's Operating Handbook and FAA Approved
Airplane Flight Manual for the Cirrus Design SR22, takeoffs are
approved with flaps up or at 50% and normal landings can be made
with any flap setting desired.
METEOROLOGICAL INFORMATION
At 1456, the reported weather conditions at Gallatin Field
Airport were wind calm, visibility 10 statute miles, sky clear,
temperature 3 degrees C, dew point -6 degrees C, and altimeter
setting 29.69 inches. At 1556, the reported weather conditions at
Gallatin Field Airport were wind calm, visibility 10 statute miles,
scattered clouds at 12,000 feet, temperature 2 degrees C, dew point
-6 degrees C, and altimeter setting 29.68 inches.
WRECKAGE AND IMPACT INFORMATION
The accident site was located in rugged mountainous terrain at
45 degrees 54.055 minutes North latitude and 110 degrees 58.802
minutes West longitude. According to measurements taken by
personnel with the Gallatin County Sheriff's Department (GCSD), the
airplane impacted trees at an elevation of 8,553 feet on a heading
of 236 degrees true and came to rest about 360 feet past the
initial impact point. Examination of photographs taken by GCSD
personnel and recovery personnel indicated that the outboard
section of the left wing, the right wingtip, the engine, the
empennage, the right main landing gear, a portion of the floor with
the aft passenger seats attached and other miscellaneous pieces
separated from the fuselage during the impact sequence. These
separated pieces were not damaged by fire. The forward section of
the fuselage and the majority of the wings were consumed by
fire.
The wreckage was recovered from the accident site on December 6,
2004, and examined on December 15, 2004, by the NTSB
investigator-in-charge and representatives of Cirrus Design
Corporation, Teledyne Continental Motors, and the FAA. All cockpit
instruments and avionics were destroyed by fire. The flight
controls and stabilizers were accounted for to include left and
right ailerons, left and right flaps, left and right horizontal
stabilizers and elevators, the vertical stabilizer and the rudder.
Flight control continuity could not be confirmed due to the extent
of damage. The flap actuator motor was recovered, and measurements
showed the actuator to be in the flaps up / zero degrees position
when compared with a flap actuator measured at the factory.
Functional testing of the flaps was precluded by impact and fire
damage.
The engine was intact with the starter separated and the
alternator partially separated. The propeller remained attached to
the crankshaft. One blade was loose in the hub, twisted toward the
direction of rotation and displayed leading edge impact marks. The
second blade was wrinkled and twisted toward the direction of
rotation. The third blade was loose in the hub, had "S" type
bending, and the tip was folded back over the non-cambered side of
the blade. The throttle, mixture and propeller controls remained
attached. The throttle shaft was bent, and the throttle valve was
frozen in place. The intake sides of the number three and five
cylinder heads were separated. The top spark plugs and valve covers
were removed, the crankshaft was rotated, and continuity was
confirmed to cylinders one, two, four and six and to the rear of
the engine. The pistons in cylinders three and five were observed
to move. Good hand compression was obtained on cylinders one, two,
four and six.
The magneto timing was checked, and the right and left magnetos
were found to be timed at 22 and 24 degrees before top dead center,
respectively. Both magnetos sparked at all terminals when rotated.
The spark plugs showed normal wear when compared to the Champion
Check A Plug card. The fuel pump had impact damage on the rear
side, and the mixture control was damaged. The drive coupling was
not damaged. The pump was rotated with a drill motor and fuel was
pumped through the unit. The fuel manifold was disassembled and
fuel was found in the interior; the diaphragm and spring were
intact and undamaged, and the fuel screen was clean. The number
five fuel injector nozzle was missing. The other nozzles were
undamaged, clean and clear. The oil filter was cut open, and the
element was clean with no metal deposits.
SURVIVAL ASPECTS
The surviving passenger (left rear seat) reported that after the
crash, he woke up laying on bare ground about 25 feet from his
seat. The passenger in the right rear seat was still strapped into
the seat and was clearly deceased. Part of the fuselage in front of
him was burning, and he heard burning behind him, but he did not
look behind him. He was wearing a t-shirt, no coat, and deck shoes.
He was missing his right shoe, his glasses and his hat. It was
freezing cold. He knew that he could find a road if he went
downhill, so he started down, plowing through snow. Near dark, he
stopped and went into a grove of trees and started to make a
shelter. He heard a helicopter and started out of the trees into an
open field. By the time he got into the open, the helicopter was
gone. He waited in the middle of the field and in about 5 minutes,
the helicopter came back, saw him, landed and picked him up. His
injuries included frostbite, cuts and bruises to his right foot,
burns on his forearms, face and the backs of his hands, and a
pelvic hernia. He was wearing his seatbelt and shoulder harness,
and he had bruises from both shoulder straps.
ADDITIONAL INFORMATION
The wreckage was released to a representative of the owner on
December 28, 2004.
In a letter dated February 1, 2005, an attorney representing the
surviving passenger wrote that the passenger told him "that before
take off the pilot indicated the flaps on the aircraft were not
functioning." On March 22, 2005, the NTSB IIC conducted a follow-up
phone interview with the surviving passenger. During this
interview, the passenger stated that while they were sitting in the
airplane before takeoff, the pilot mentioned that the flaps were
not working. This took place during the running of the electronic
checklist. None of the passengers questioned the pilot about the
flaps. The passenger heard a high-pitched whine (like the sound he
heard during the flight just before the crash) at some point during
the time the pilot was running the electronic checklist. He could
not recall whether this happened before or after the pilot's
comment about the flaps not working. The passenger stated that he
was sure the flaps were not down for takeoff, since he recalls the
pilot and the right front seat passenger discussing the need for
extra speed on the takeoff roll.
The National Transportation Safety Board determines the
probable cause(s) of this accident as follows:
The pilot's failure to maintain altitude/clearance while
maneuvering in mountainous terrain, which resulted in an inflight
collision with trees and terrain. Contributing factors were the
mountainous terrain and the downdraft.