NTSB Factual Report

HISTORY OF FLIGHT

On September 10, 1993, about 1750 hours eastern daylight time, N6013J, a Cessna A150, registered to Metropolitan Aviation, Inc., Fort Washington, Maryland, was destroyed after impacting trees and terrain in Greenbelt, Maryland, following an uncontrolled descent. The certificated private pilot and student pilot were fatally injured. Visual meteorological conditions prevailed and a flight plan was not filed. The local flight departed from Friendly, Maryland, and was conducted under 14 CFR 91.

According to a witness, the private pilot arrived at the Potomac Airfield, Friendly, Maryland, and was met by the student pilot. The witness personally filled the airplane with 100 low lead aviation fuel for the flight. He observed the pilot make a call from a public telephone and then pre-flight the airplane. After the pre-flight, both the private pilot and student pilot boarded the airplane, taxied to runway 24, and took off. The witness stated that the "takeoff appeared to be normal" and the airplane departed the traffic pattern to the north.

Another witness, a co-worker of the private pilot who lives near the accident site, reported that the private pilot contacted him by telephone just prior to departure to let him know that he would be flying over his home.

According to FAA Air Traffic Control transcripts, the private pilot contacted Andrews Air Force Base Terminal Radar Approach Control at 1735 hours and requested clearance to "College Park", an airport located 2.47 nautical miles from the accident site. At 1736 hours, the pilot was given clearance to enter the terminal control area (TCA) at 1,400 feet. At 1741 hours, the pilot transmitted "I'm going to go over to Greenbelt and do some airwork over Greenbelt so whenever you can dump us out of the TCA on this heading will be fine." At 1745, the pilot was told that he was "leaving the TCA beneath the floor." Radar service was terminated and the pilot was told to "squawk 1200." The pilot responded with "thank you very much for your help." This was the last transmission recorded by the pilot.

According to several ground witnesses who were near the accident site, the airplane was "circling" and "flying low" for about five minutes before it was observed to initiate a "steep" climb, suddenly nose over, and "spin" into the ground. Many of the witnesses reported hearing the engine "rev up" and become quiet several times while the airplane was circling. One witness stated that the pilot was "practicing stalls". Some of the witnesses reported that the engine "sputtered" and "quit" just before the airplane descended toward the ground. The airplane impacted trees, came to rest on its nose in the backyard of a home, and burned.

The accident occurred during the hours of daylight at 39 degrees, 0.28 minutes North and 76 degrees, 52.82 minutes West.

PERSONNEL INFORMATION

The pilot seated in the left front seat, age 41, was a certificated private pilot with a rating for single engine land airplanes. According to FAA records, the pilot was issued a FAA Second Class Medical Certificate on March 10, 1992, with no limitations. The pilot's logbook detailing his aeronautical experience was recovered at the accident site. The last entry listed in the logbook was dated August 21, 1993. As of that date, the pilot had logged a total of 638 hours.

The student pilot seated in the right front seat, age 42, was issued a FAA Third Class Medical Certificate and Student Pilot Certificate on June 22, 1993. According to FAA records, she reported 115 hours of flight time at the time of her medical application.

AIRCRAFT INFORMATION

An examination of the airplane's engine and airframe logbooks, and the airplane's "squawk record", did not reveal any unresolved discrepancies prior to departure the day of the accident.

WRECKAGE AND IMPACT INFORMATION

The airplane wreckage was examined at the accident site on the evening of the accident, September 10, 1993, and again on September 11, 1993. An additional examination occurred on September 15, 1993, at Dawn Aeronautics in New Castle, Delaware, after the wreckage had been moved.

The airplane came to rest about 12 feet from a house in a residential area. A broken tree limb was found about 65 feet directly above the wreckage. The left wing and fuel tank of the airplane were imbedded around another tree. The magnetic bearing of the airplane was about 306 degrees. The airplane was imbedded into the ground at an angle of about 60 degrees from the horizon. There was evidence of a ground fire near the cabin and engine area.

All primary and secondary flight control surfaces were accounted for at the accident site. The right wing and empennage were separated from the remainder of the airframe and were located within the dimensions of the airplane. No evidence was found to indicate a flight control deficiency. The leading edges of both wings of the airplane exhibited evidence of "accordion" crush damage. The engine was crushed upward into the cockpit. The engine and propeller remained attached to the airframe and were embedded into the ground in a nose down attitude.

The electrically-driven flap actuator mechanism was examined; none of the threads from the mechanism's jackscrew were exposed. According to engineering data from the Cessna Aircraft Company, the lack of exposed threads indicates that the flaps were in the fully retracted position.

Both wing fuel tanks and associated fuel lines were compromised. Evidence of a ground fire was found in the center of the wreckage, The carburetor was crushed, burned, and partially separated from the engine.

The instrument panel was destroyed by fire. About 2.2 inches of the throttle control shaft protruded from the panel and was bent.

The mixture control was found in the full rich position. The fuel shutoff valve handle was found in the ON position. The altimeter indicated zero feet with an altimeter setting of 29.72 inches. No other indications from the cockpit could be read.

The engine, a Continental model O-200-A, and propeller were examined. No holes were found in the crankcase. The bottom of the engine exhibited crush and fire damage and the oil sump was deformed. About three quarts of oil were found in the sump; no contamination was noted. The oil screen was removed and examined; no contamination was noted. The crankshaft had been pushed rearward about 1/8 inch. The propeller flange was cracked and bent. The propeller could be rotated through about 60 degrees of rotation. Crankshaft drive and valve train continuity was verified for all four cylinders during propeller rotation. The magnetos were removed and the interior of the engine was visible. No evidence of heat distress was found. Continuity of all connecting rods was verified.

The magnetos exhibited evidence of impact and fire damage. Both of the magnetos could be freely rotated and the impulse couplings could be engaged.

The carburetor was separated from the intake manifold assembly and was attached to the engine by the throttle linkage. An external examination revealed evidence of fire damage. The carburetor heat control was found in the COLD position. The carburetor was disassembled and examined. The venturi and accelerator pump were intact. Thermal damaged was noted on the composite floats. The carburetor bowl was empty. The carburetor fuel screen was removed and examined; it was coated with an oily, sticky substance which resembled partially oxidized fuel residue.

The two-bladed McCauley metal propeller was examined. One blade exhibited evidence of chordwise scratching and was bent aft about 35 degrees. The other blade did not exhibit evident of chordwise scratching and was bent aft about 35 degrees.

MEDICAL AND PATHOLOGICAL INFORMATION

The autopsy of the private pilot was performed on September 11, 1993, by Dr. Margarita A. Korell at the Office of the Chief Medical Examiner, Baltimore, Maryland. The cause of death listed on the report of autopsy was "Multiple Injuries - Accident". No pre-existing conditions were noted on the report of autopsy. A toxicological examination was conducted on specimens from the private pilot by the FAA Civil Aeromedical Institute. The results of the examination were reported to be negative for all screened drugs and alcohol.

The autopsy of the student pilot was performed on September 11, 1993, by Dr. Margarita A. Korell, M.D., at the Office of the Chief Medical Examiner, Baltimore, Maryland. The cause of death listed on the report of autopsy was "Multiple Injuries - Accident". No pre-existing conditions were noted on the report of autopsy. A toxicological examination was conducted on blood specimens from the student pilot by the Office of the Chief Medical Examiner for the State of Maryland. The results of the examination were negative for ethanol and carbon monoxide.

ADDITIONAL INFORMATION

A recorded radar data study was performed by the Safety Board and is attached. The study utilized recorded radar data extractor tapes of Automated Terminal System (ARTS) III data from the Baltimore-Washington International Airport and Washington National Airport's Terminal Radar Approach Control from the day of the accident. According to the study:

"Inspection of N6013J's flightpath plot revealed the first recorded 1200 beacon code beacon target return at 1746:04 EDT at a Mode C altitude of 1200 Feet Mean Sea Level (MSL). . . . N6013J's groundtrack indicated northerly flight until 1749:14.5 EDT, when the data indicated a turn to the east.

"For the next approximately 4.5 minutes, N6013J's recorded radar groundtrack indicated a series of circling turns - three clockwise and one counterclockwise. . . . The recorded Mode C altitude during the circling maneuvers ranged from 1100 to 500 feet MSL, with an approximate average of 800 feet MSL. The last recorded [beacon target] was at 1753:47 Local , with a recorded Mode C altitude of 800 Feet MSL. The final four recorded returns (covering approximately 14 seconds) indicated N6013J was travelling southeast, with an average groundspeed through the segment of 61.3 knots."

At 1755 hours, the recorded wind speed and direction at Andrews Air Force Base, located 11.5 nautical miles south of the accident site, was 17 knots at 280 degrees. This would impart a tail wind component on the airplane as it progressed along the path of its last 14 seconds of recorded flight. Therefore, the actual airspeed of the airplane would be less than the recorded groundspeed of 61.3 knots. According to the Cessna 1972 Model 150 Aerobat Owner's Manual, page 7-2, the airspeed at which the airplane will stall is about 48 knots with the flaps retracted and a zero degree bank angle, and about 55 knots with retracted flaps and a bank angle of 40 degrees.

The aircraft wreckage was released to Mr. James McArthur, Critenden Adjustment Company, representing the owner, on September 15, 1993.

NTSB Probable Cause

1) THE PILOT'S POOR JUDGEMENT IN BUZZING A RESIDENTIAL AREA, 2) HIS FAILURE TO MAINTAIN AN AIRSPEED ABOVE THE AERODYNAMIC STALLING SPEED, WHICH LED TO A STALL/SPIN, AND 3) THE INABILITY OF THE PILOT TO TAKE REMEDIAL ACTION AND RECOVER FROM THE STALL/SPIN DUE TO INSUFFICIENT ALTITUDE.