NTSB Factual Report

HISTORY OF THE FLIGHT

On October 8, 1994, about 1000 eastern daylight time, a Cessna 172N, N4851D, registered to Naples Air Center, crashed in the Big Cypress National Preserve, Ochopee, Florida, while on a 14 CFR Part 91 aerial observation flight. Visual meteorological conditions prevailed at the time and a visual flight rules flight plan was filed, but not activated. The aircraft was destroyed and the commercial-rated pilot and two passengers were fatally injured. The flight originated at Naples, Florida, on October 8, 1994, about 0702.

Witnesses observed the aircraft approach from the south at a low altitude and circle in the area of their camp. The aircraft made three turns to the right and then headed toward the southeast. Engine power was being reduced and increased during the maneuvering. The aircraft descended to tree top level and then entered a steep climb. The right wing and nose of the aircraft dropped and the aircraft descended nose down until ground impact.

Voice recordings from the Naples Airport Control Tower indicated the flight departed at 0702. The next reported contact with the flight was by the Everglades National Park personnel at 0942, when the flight reported it was doing low level panther telemetry tracking. After the accident the aircraft's flight hour recording meter, or hobbsmeter, indicated the aircraft had flown 3.0 flight hours since departure.

The aircraft was being operated by Naples Air Center under contract to the University of Tennessee, Knoxville, Tennessee. The purpose of the flight was to record radio telemetry information from Florida panthers. The University of Tennessee is under contract with the United States National Park Service to research "Effects of public use on Florida panthers on addition lands of Big Cypress National Preserve." Neither the National Park Service and University of Tennessee contract or the University of Tennessee and Naples Air Center contract gave specific flight procedures to be followed for the flights.

PERSONNEL INFORMATION

This was the pilot's first panther tracking flight. The pilot had been briefed on the procedures for the flight by other pilots at Naples Air Center, but had not observed on any of the flights. Additional information on the pilot is contained in this report under First Pilot Information and in attachments to this report.

AIRCRAFT INFORMATION

Information on the aircraft is include in this report under Aircraft Information.

METEOROLOGICAL INFORMATION

Visual meteorological conditions prevailed at the time of the accident. Meteorological information is contained in this report under Weather Information.

WRECKAGE AND IMPACT INFORMATION

The aircraft crashed in the Big Cypress National Preserve, at latitude 25 deg. 55' 51" North and longitude 81 deg. 00' 53" West, or about 4 nm north of the Oasis Ranger Station located on U.S. Highway 41. Examination of the crash site indicated the aircraft impacted in the swamp in a near nose down vertical descent. The right wing tip impacted first and the aircraft rotated across the right wing leading edge, nose, and then left wing leading, came to an abrupt halt, and the tail section broke to the left.

All components of the aircraft which are necessary for flight were located on the main wreckage of the aircraft. Continuity was established within the aileron, rudder, elevator, and elevator trim control systems. The wing trailing edge flap motor was found in the flap 15 degree extended position. The elevator trim tab actuator was found in the 3 degree tab down, or aircraft nose up position.

The pilot's seat was found loose from the tracks and in a forward position. The seat was held in place by the lap seat belt. The tracks were bent upward forward of the 4th locking hole from the front of the track. Locks to prevent forward and aft slippage of this seat were in place. The right front passengers seat was found loose from the tracks and in a forward position. The seat was held in place by the lap seat belt. The tracks were bent upward forward of the 4th locking hole from the front of the track. Locks to prevent forward and aft slippage of this seat were in place.

Examination of the engine indicated that it rotated normally and continuity was established within the crankcase, valve train, and accessory drives. Cylinders numbers 2, 3, and 4 produced normal compression. The number 1 cylinder produced low compression and the exhaust valve was found to be held partially open by carbon debris. Each spark plug had coloring indicative of normal engine operation. The ignition switch operated normally. Each magneto produced spark when rotated.

The carburetor float and needle shutoff valve operated normally. All nozzles and openings within the carburetor were unobstructed. Fuel was found in all airframe and engine fuel system components. The exhaust system was unobstructed and there were no holes in the muffler due to rust or corrosion. The propeller had bending damage indicative of rotation under power at impact. The front face of the propeller blades had chordwise scratches.

Examination of the emergency locator transmitter indicated it had not activated. The switch was found in the armed position and the external antenna was connected. The battery voltage was found to be within normal limits. The unit activated when the switch was moved to the on position. The unit did not activate when the switch was placed in the armed position and forces were applied to the unit. The unit's "G" switch was found to be stuck in the off position.

MEDICAL AND PATHOLOGICAL INFORMATION

Post mortem examination of the pilot and two passengers was performed by Marta Coburn, M.D., Medical Examiner, Naples, Florida. The cause of death for each occupant was multiple extreme injuries. Post mortem toxicology studies on specimens obtained from the pilot and two passengers was performed by the Medical Examiner's Office, Naples, Florida. The tests were positive for 2.5% or less carbon monoxide in each occupant. The tests were negative for ethanol, basic, acidic, and neutral drugs. Additional medical and pathological information is contained in Supplement K and attachments to this report.

TEST AND RESEARCH

The chief pilot for Naples Air Center stated Naples Air Center had been doing these flights for over 12 years for the State of Florida. They had only been flying for the University of Tennessee for a month. The flight procedures were the same for the University of Tennessee and the State of Florida. A visual flight rules flight plan is always on file for the flights and the pilot would have to activate it with the FAA Miami Flight Service Station. The pilot would then be required to maintain contact with the Everglades National Park personnel by radio. The flights would start out at 1,000 feet and once the signal from the panther was received the researcher would direct the pilot toward it. The flight would then descend to no lower than 500 feet. The aircraft would be slowed using 10 degrees of wing flaps as the position of the panther is located. The pilot always had control of the flight.

ADDITIONAL INFORMATION

The aircraft wreckage was released on October 13, 1994, to Richard Gentile, President, Naples Air Center. All components retained for further examination were returned to Richard Gentile.

NTSB Probable Cause

THE PILOT'S FAILURE TO MAINTAIN AIRSPEED WHILE MANEUVERING RESULTING IN AN INADVERTENT STALL AND AN UNCONTROLLED DESCENT UNTIL IMPACT IN A SWAMP.