NTSB Factual Report

HISTORY OF FLIGHT

On April 18, 2008, at 1250 Pacific daylight time, a Cessna 150J floatplane, N60760, was destroyed when it impacted rugged terrain in the Emigrant Wilderness Area, near Sonora, California. The airline transport pilot flight instructor and commercially certificated student were killed. Seaplane Ventures, Inc., was operating the floatplane under 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed for the instructional flight. The floatplane departed from a pond on a private cattle ranch near Angels Camp, California, 38 minutes before the accident. A flight plan had not been filed.

On the day of the accident, two commercial pilots came to the flight instructor for currency training in his fixed float equipped airplane. The first pilot receiving instruction said that they departed at approximately 0930, and the plan was to practice landings on two nearby reservoirs. Both of these reservoirs were at approximately 1,100 feet elevation, which was about the same elevation as the home base pond. They flew for 1.7 hours and returned to the pond for lunch. Their flight was uneventful.

The first pilot reported that the airplane departed for its second training flight at 1212. The second pilot receiving instruction had requested to see some high mountain lakes and they had planned to fly directly to Cherry Lake (elevation 4,698 feet). The second pilot was an enthusiastic photographer, and he was planning to document the entire flight while the flight instructor was flying.

Digital photographic data recovered from the wreckage indicated that the floatplane flew directly to Cherry Lake and they made one touch-and-go landing, from north to south, at the north end of the lake. Then the floatplane reversed course and flew north towards rising terrain.

An Emergency Locator Transmitter (ELT) signal was received by the U.S. Air Force Rescue Coordination Center, at Tyndall Air Force Base, Florida. Concerned friends of the overdue flight instructor and second pilot commenced an aerial search; the airplane was located late that afternoon.

PERSONNEL INFORMATION

The 38-year-old flight instructor's most recent first-class Federal Aviation Administration (FAA) medical certificate was issued on November 6, 2007. He held an airline transport pilot certificate with a multi-engine land airplane rating with commercial privileges in single engine land and sea airplanes. He was a flight instructor in single engine, multi-engine and instrument. He had an advanced ground instructor's certificate. His total flight experience was estimated to be 7,000 hours, with 200 hours in the make and model airplane involved in the accident.

The 56-year-old second pilot's most recent second-class FAA medical certificate was issued on November 2, 2006. He was a commercially certificated pilot with single engine land and sea, multi-engine and glider ratings; he had an instrument rating and he was a flight instructor in gliders. He had an estimated 1,500 hours of flight time, with 25 hours in the make and model airplane involved in the accident.

AIRCRAFT INFORMATION

The airplane was a single engine, propeller-driven, two seat airplane, with dual flight controls, which was manufactured by Cessna Aircraft Company in 1969. Its maximum takeoff gross weight was 1,700 pounds; its empty weight was 1,183 pounds. It was powered by a Lycoming O-320-E2D (STC#SA572CE), reciprocating, direct drive, air-cooled, normally aspirated engine, which had a maximum takeoff rating of 150 horsepower at sea level.

A review of the maintenance records indicated that the last annual inspection was performed on October 5, 2007; the last 100-hour inspection was performed on March 31, 2008. The airframe had 7,849 hours on it at the time of its last 100-hour inspection. On February 7, 2004, the floats were installed on the airplane in accordance with Cessna's Type Certificate No. 3A19.

The previous owner of the airplane reported takeoff configuration was 20 degrees of flaps, and climb required 10 degrees of flaps. The flight instructor purchased the airplane on November 16, 2007. The last weight and balance was dated September 20, 2005; the airplane's weight was 1,183 pounds, and it had a useful load of 517 pounds.

According to the occupant's FAA airmen's medical data, the flight instructor weighed 227 pounds and the second pilot weighed 180 pounds.

The airplane was equipped with two 13-gallon wing tanks; the first pilot stated that when the airplane departed, the left wing tank was full and the right wing tank was half full. The estimated fuel at departure was 19.5 gallons, or 117 pounds. The airplane's total weight at departure was estimated at 1,707 pounds.

METEOROLOGICAL INFORMATION

At 1253, the weather conditions at Modesto County Airport (MOD; elevation 97 feet), Modesto, California, located 220 degrees and 55 nautical miles (nm) from the accident site, were as follows: wind variable at 4 knots; visibility 10 statute miles; clear of clouds; temperature 79 degrees Fahrenheit; dew point 37 degrees Fahrenheit; altimeter setting 29.91 inches of Mercury.

At 1300, the temperature at Spring Gap Forebay (SFB; elevation 5,100 feet) weather facility near Pinecrest, California, which was 270 degrees and 11 nm from the accident site, was 67 degrees Fahrenheit. The density altitude at the accident site, at the time of the accident, was calculated to be 6,907 feet.

The weather conditions estimated by the first responders for the time of the accident, at the south end of the lake near the dam, were clear skies with strong and gusty winds out of the south. The wind was estimated at 10 knots, gusting to 20 knots. These same wind conditions were present the following day when rescuers were at the site. A pilot that had landed on the lake many times said that by midday, the wind generally rises up the mountain and accelerates over the water due to the funneling effect off the mountains on either side. The lake is oriented south to north, and the accident site is about a mile north of the lake in a valley, which contains the stream, which supplies Cherry Lake.

WRECKAGE AND IMPACT INFORMATION

The airplane was found in rugged, mountainous terrain (elevation 5,200 feet), near Sonora. The terrain is glacially landscaped with granitic ridges and valleys. The area was sparsely vegetated with conifers to 60 feet. The airplane was found resting on its nose and the leading edges of its wings. The nose was crushed aft, and the engine was displaced into the cabin. The wing leading edges were crushed aft to the wing spars in an accordion like manner, and the forward ends of the floats were crushed aft to the forward attachment points. A ground scar extended on a 355-degree course for 33 feet, and the airplane came to rest oriented 180 degrees. All of the airplane's major components were accounted for at the accident site.

The fuselage was wrinkled and compressed to just behind the cabin area. The empennage was bent down in reverse scorpion manner. Flight control cable continuity was confirmed from the cockpit controls to each aerodynamic surface. The flap actuator measurement corresponded to approximately 9 degrees. No anomalies were found with the airplane's fuel system.

The engine case was found cracked near the nose, and the crankshaft was found broken inside the case and could not be rotated. The oil sump had broken free from the case and its pieces were scattered along the ground scar leading to the wreckage. The carburetor had separated from the engine and its pieces were also scattered along the ground scar. The spark plugs appeared normal. Both magnetos were found broken free, and when they were rotated by hand produced sparks at all leads. The propeller blades had chord wise groves near the hub and on one blade tip.

No evidence of any preimpact mechanical discrepancies was found with the airplane's airframe or engine that would have prevented normal operation. There was no postimpact fire.

MEDICAL AND PATHOLOGICAL INFORMATION

The Tuolumne County, Office Of The Coroner, performed autopsies on both pilots on April 21, 2008. They determined that the cause of death for both of the occupants was multiple blunt traumas.

The FAA's Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma, performed toxicology tests on the flight instructor and the second pilot. According to CAMI's report on the flight instructor, carbon monoxide and cyanide tests were not performed. His urine was tested for volatiles and drugs, with negative results.

The second pilot was also not tested for carbon monoxide and cyanide. His urine was tested for volatiles, with negative results, however, the testing for drugs in his urine detected Ibuprofen. The second pilot's wife was contacted and she reported that he had fallen in the home 2 or 3 days before the accident. She said he had taken Ibuprofen for a day or two, but to the best of her knowledge he was feeling fine on the morning of the accident.

NTSB Probable Cause

The pilot's failure to maintain airspeed while maneuvering, resulting in an aerodynamic stall and loss of aircraft control. Contributing to the accident were rising mountainous terrain and a high density altitude.