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 the floatplane. The first pilot receiving instruction said that they departed at approximately 0930, and the plan was to practice landings on two nearby reservoirs. Both reservoirs were at approximately 1,100 feet elevation. 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 had requested to see some high mountain lakes, and they planned to fly directly to Cherry Lake (elevation 4,698 feet). The second pilot was an enthusiastic photographer, planning to document the entire flight while the flight instructor flew.
Digital photographic data recovered from the wreckage indicated that the floatplane flew directly to Cherry Lake and made one touch-and-go landing, from north to south, at the north end of the lake. Then it 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. 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 FAA medical certificate was issued on November 6, 2007. He held an airline transport pilot certificate with a multi-engine land airplane rating and commercial privileges in single-engine land and sea airplanes. He was a flight instructor in single-engine, multi-engine, and instrument, and held an advanced ground instructor certificate. His total flight experience was estimated at 7,000 hours, with 200 hours in the accident make and model.
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 was a flight instructor in gliders. He had an estimated 1,500 hours of flight time, with 25 hours in the accident make and model.
Aircraft Information
The airplane was a single-engine, propeller-driven, two-seat airplane with dual flight controls, manufactured by Cessna Aircraft Company in 1969. Its maximum takeoff gross weight was 1,700 pounds; empty weight was 1,183 pounds. It was powered by a Lycoming O-320-E2D engine with 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 at the last 100-hour inspection. On February 7, 2004, floats were installed in accordance with Cessna's Type Certificate No. 3A19.
The previous owner 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, dated September 20, 2005, showed an empty weight of 1,183 pounds and a useful load of 517 pounds.
According to FAA airmen's medical data, the flight instructor weighed 227 pounds and the second pilot weighed 180 pounds. The airplane had two 13-gallon wing tanks; the first pilot stated that at departure, the left tank was full and the right half full, for an estimated 19.5 gallons (117 pounds) of fuel. The airplane's total weight at departure was estimated at 1,707 pounds.
Meteorological Information
At 1253, weather at Modesto County Airport (elevation 97 feet), located 220 degrees and 55 nautical miles from the accident site, was: wind variable at 4 knots; visibility 10 statute miles; clear of clouds; temperature 79°F; dew point 37°F; altimeter 29.91 inHg.
At 1300, the temperature at Spring Gap Forebay (elevation 5,100 feet), 270 degrees and 11 nautical miles from the accident site, was 67°F. The density altitude at the accident site at the time of the accident was calculated to be 6,907 feet.
First responders estimated weather at the south end of the lake near the dam: clear skies with strong and gusty winds out of the south, estimated at 10 knots gusting to 20 knots. Similar conditions were present the following day. A pilot familiar with the lake reported that by midday, wind generally rises up the mountain and accelerates over the water due to the funneling effect of the surrounding mountains. The lake is oriented south to north, and the accident site is about a mile north of the lake in a valley containing a stream that 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, sparsely vegetated with conifers up to 60 feet. The airplane rested 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 major components were accounted for.
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 cockpit controls to each aerodynamic surface. The flap actuator measurement corresponded to approximately 9 degrees. No anomalies were found with the fuel system.
The engine case was cracked near the nose, and the crankshaft was broken inside the case and could not be rotated. The oil sump had broken free from the case, with pieces scattered along the ground scar. The carburetor had separated from the engine, its pieces also scattered. Spark plugs appeared normal. Both magnetos were broken free and produced sparks at all leads when rotated by hand. Propeller blades had chordwise grooves near the hub and on one blade tip.
No evidence of any preimpact mechanical discrepancies was found with the 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. The cause of death for both occupants was multiple blunt traumas.
The FAA's Civil Aeromedical Institute (CAMI) performed toxicology tests on the flight instructor and the second pilot. For the flight instructor, carbon monoxide and cyanide tests were not performed. Urine tests for volatiles and drugs were negative.
For the second pilot, carbon monoxide and cyanide tests were not performed. Urine tests for volatiles were negative, but drug testing detected Ibuprofen. The second pilot's wife reported that he had fallen at home 2 or 3 days before the accident and 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.