Aviation Accident Summaries

Aviation Accident Summary ANC98FA048

PALMER, AK, USA

Aircraft #1

N9212H

Cessna 172M

Analysis

The noninstrument rated private pilot was issued adverse condition warnings and urgent pilot reports for severe turbulence. His route of flight took him up channeled, mountainous terrain requiring a climb to a minimum of 9,000 feet msl. Winds aloft were forecast to be between 28 and 41 knots. Surface winds were forecast to be in a downslope direction at 25 knots gusting to 50 knots from channeled terrain. Cessna 172 performance charts for the 180 horsepower engine indicate a maximum climb rate available of 405 feet per minute at 8,000 feet pressure altitude. Ceilings of 8,500 feet were reported on the west side of the mountains. The pilot radioed that he was going to try to get on top through a hole. The airplane was located on the west side of a peak, in deep snow, at 8,600 feet msl, about 40 hours after the departure. The Emergency Locator Transmitter signal was masked by terrain and wreckage. Both occupants were lightly dressed, and appeared to have survived the impact. The pilot was described by acquaintances as inexperienced and prone to taking chances with the airplane.

Factual Information

HISTORY OF FLIGHT On May 15, 1998, about 0915 Alaska daylight time, a Cessna 172M airplane, N9212H, was destroyed when it impacted mountainous terrain near the 8,600 feet msl level of the Radcliffe Glacier, about 38 miles east of Palmer, Alaska, at position 61 degrees, 21 minutes North latitude, 147 degrees, 52 minutes West longitude. The private pilot and the sole passenger sustained fatal injuries. The flight was conducted under 14 CFR Part 91, as a personal flight from Big Lake, Alaska, to Petersburg, Alaska. Visual meteorological conditions prevailed at Palmer, Alaska, at the time of the accident. Weather at the accident site is unknown. A direct route of flight from Big Lake to the location of the wreckage would have taken the airplane over the Knik Glacier. This glacier constitutes continually rising terrain from Palmer, to the crest of the Chugach Mountain Range. The mountains are extremely rugged, and covered by glaciers and a large ice field at the higher elevations. The ice field area where the airplane came to rest is surrounded by peaks extending to 10,610 feet msl. The general direction of flight is eastward, and required the airplane climb from sea level to a minimum of 9,000 feet msl to clear the passes. The airplane was reported overdue by a friend in Petersburg, Alaska, at 1100 on May 16. The airplane was located about 2300 on May 16, by an Alaska Air National Guard C-130 airplane. INJURIES TO PERSONS Both occupants were confirmed to be deceased about 2300 on May 16. Severe injuries were not described by the two National Guard pararescuemen (PJs) who reached the site. The PJs described both occupants located outside, and below the airplane by 10 and 20 feet respectively. Footprints were visible in the snow surrounding the airplane fuselage and the two occupants prior to the arrival of the PJs. The female occupant was dressed in long pants and a sweater. The male was dressed in long pants and a medium weight jacket. Neither were wearing gloves. The male appeared to be wearing a hat. The National Guard mission report comments included, "It appeared both died of hypothermia." Other handwritten mission notes stated, "guy had injuries." DAMAGE TO AIRCRAFT The airplane sustained substantial damage, and has not been recovered. PERSONNEL INFORMATION The pilot held a private certificate for single engine land airplanes. He did not hold an instrument rating. His third class medical certificate was valid, with no restrictions. At the time of his last FAA medical examination he stated that he had accumulated 288 hours of flight time. He received his private pilot certificate on March 15, 1988. The passenger was not a licensed pilot, but reportedly had soloed as a student. No FAA records of pilot experience of the passenger were received. Interviews obtained by the Alaska State Troopers, and the Alaska National Guard, included the following statements from acquaintances and friends of the pilot: "The aircraft was fully equipped with nav gear and radio equipment, of which the pilot did not know how to operate any of it for the most part other than the radio." A friend's wife stated that her husband "didn't fly with the pilot because he wasn't an experienced pilot and took too many chances." This friend himself said that "the pilot was very inexperienced as a pilot and didn't think twice about taking chances with the aircraft." AIRCRAFT INFORMATION The pilot purchased the airplane in 1997. The airplane was a Cessna 172M, modified by Supplemental Type Certificate with a Lycoming O-360-A1A engine, serial number L-23074-36A. The engine was rated to produce 180 horsepower at sea level at 2,700 propeller rpm. The airplane had a Sensinich model 76EM8S14-0-56 fixed pitch propeller, serial number 26581K. The propeller was repitched from 60 inches (cruise propeller) to 56 inches (climb propeller) prior to purchase by the pilot. The Cessna 172Q operator's handbook, provides a rate of climb chart for Cessna 172 airplanes with an O-360 engine. This chart indicates that at 8,000 feet pressure altitude, an outside air temperature of 0 degrees C, a gross weight of 2,550 pounds, and a 76 inch long propeller pitched to 58 inches, that a climb rate of 405 feet per minute is available. This chart does not account for any additional climb rate available with a climb propeller. The last weight and balance form for the airplane revealed an empty weight of 1,552 pounds. Full fuel of 48 gallons weighs 288 pounds. The Cessna 172Q fuel consumption chart indicates 1.4 gallons (8.4 pounds) consumed for taxi and 3.6 gallons (21.6 pounds) consumed to 8,000 feet. The pilot weighed 238 pounds according to his third class medical. The passenger weighed 128 pounds according to her driver's license. Total weight estimated at the time of the accident, excluding any personal items or cargo, is 2,176 pounds. METEOROLOGICAL INFORMATION Visual meteorological conditions prevailed at Big Lake (150 feet msl), and Palmer (248 feet msl) at the time of departure. The weather conditions at the accident site are unknown. Flight precautions for severe turbulence and mountain obscurations were in effect in the area forecast for the time of the accident. The area forecast called for strong low level winds to intensify, and for surface winds out of passes and channeled terrain from the east and southeast of 25 knots gusting to 50 knots. All passes were forecast to be turbulent. The weather reported at Palmer at 0853 was, scattered clouds at 7,000 feet, broken clouds at 8,500 feet, winds 130 degrees magnetic at 25 knots gusting to 32 knots. Visibility was reported as 7 miles with blowing dust in all quadrants. The weather reported at Whittier at 0854 was, ceilings overcast at 7,000 feet, winds 080 degrees magnetic at 10 knots. COMMUNICATIONS The last radio contact was at 0847 on May 15 with the FAA Kenai Flight Service Station, when the pilot requested current weather at Valdez. He was told that Valdez ceilings were 10,000 feet msl. The FSS specialist then stated, "we do have some urgent pilot reports of moderate to severe turbulence in the Anchorage Bowl area." The pilot was also advised of adverse conditions of turbulence, low level wind shear, mountain obscuration, icing, and isolated IFR. The pilot stated to the FSS specialist at 0847 that, "...I'm heading down Knik Arm to look to see if I can go over the top. It looks good from here. If I see a hole I'm going to file a flight plan. Probably be 20-25 minutes. Otherwise we are going to have to take an alternate route." No flight plan was filed. WRECKAGE AND IMPACT INFORMATION The National Guard rescue mission notes state that the airplane came to rest at the 8,600 feet msl level on the western side of the western most peak of Radcliffe Glacier. A review of photographs taken by the Air National Guard helicopter crew who confirmed the fatalities indicated the airplane came to rest on a magnetic heading about 330 degrees. The wide pass in which the airplane was located is oriented generally east-west (070/250 degrees magnetic). After the wreckage was located on May 16, and the two occupants were confirmed to be fatalities, three attempts were made by the NTSB and Alaska State Troopers to reach the site, extract the occupants, and examine the wreckage. The first two attempts, on May 19 and May 23, were abandoned due to weather at the accident site. On June 3, the NTSB IIC and a team of five other climbers reached the geographic location of the crash site. Large amounts of accumulated snow and avalanches had buried the airplane. Several hours of probing the crash site using avalanche rescue techniques failed to locate the wreckage. The NTSB IIC conducted an overflight of the area on August 14, and observed large amounts of new snow, and extensive, new avalanche fields along the entire mountain slope where the airplane wreckage had been sighted. These avalanche fields had not been present on June 3. A review of photographs taken by the Alaska National Guard 210th Rescue Squadron on May 16, revealed the left wing attached to the center cabin assembly. This assembly came to rest in an upright position, with the nose in to the 45 degree slope. The right wing was not visible. The left wing tip was torn open in an upward direction. The entire left wing appeared to be deflected downward and aft at the fuselage attach joint, with a 45 degree crease extending from the forward fuselage attachment to midspan on the left flap. The left flap appeared to be extended to the 20 degree position. The empennage was separated from the fuselage center section at the rear window. This section was laying immediately to the left side of the fuselage, partially inverted. It appears that the top surface mounted Emergency Locator Transmitter antenna was partially buried in snow, and located under the left wing. The underside of the empennage and tail cone did not show damage. The right horizontal stabilizer appears undamaged. The top of the vertical stabilizer, and the left horizontal stabilizer are bent up and to the right. The trim tab on the trailing edge of the right elevator is deflected upwards to a position corresponding to a setting halfway between neutral (takeoff) and full nose down. The mission notes from the Alaska Air National Guard helicopter crew stated "...the aircraft was in a nose down position with the wings broken off near the fuselage. Only the first 3 of the serial number were visible, N92...nosed in / badly damaged / wings alongside fuselage." MEDICAL AND PATHOLOGICAL INFORMATION The occupants were not recovered and no toxicological samples were obtained. SURVIVAL ASPECTS About 2100 on May 16, an Alaska National Guard rescue C-130 detected a weak ELT signal, and located the wreckage. The crew stated that the ELT was only detectable in the bowl of the glacier where the airplane came to rest. No signal was received by search and rescue satellites. Mission comments from the helicopter rescue crew who reached the wreckage stated "...confirmed 2 deceased...It appeared both died from hypothermia." The airplane was reported to be equipped with a tent and sleeping bags. The helicopter crew told the IIC that only one of the deceased was wrapped in a sleeping bag. Winds aloft and temperatures forecast for 9,000 feet msl at Anchorage were 41 knots and 21 degrees Fahrenheit (F). At Middleton Island, Alaska, the forecast was 28 knots and 21 degrees F. ADDITIONAL INFORMATION Attempts to recover the airplane or occupants was suspended by the Alaska State Troopers on June 4, pending future information that the wreckage has become uncovered and is able to be reached. No one representing the pilot's estate was able to complete an NTSB 6120.1/2 Pilot/Operator Report.

Probable Cause and Findings

The pilot's intentional flight into known adverse weather conditions. Contributing factors were the terrain induced turbulence, clouds, the pilot's overconfidence in his abilities, and mountainous terrain conditions.

 

Source: NTSB Aviation Accident Database

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