NTSB Factual Report

HISTORY OF FLIGHT

On June 13, 2016, at 0957 eastern daylight time, a Cessna 150F airplane, N102DK, impacted trees and terrain after departure from Butler Field Airport (IN46), Rockville, Indiana. The pilot and passenger were fatally injured, and the airplane was destroyed. The airplane was registered to and operated by a private individual as a 14 Code of Federal Regulations Part 91 personal flight. Day visual meteorological conditions existed about the time of the accident near the accident site, and no flight plan filed. The flight was destined for Eagle Creek Airpark, Indianapolis, Indiana.

According to a witness who was mowing grass at IN46, the airplane lifted off from the grass runway near midfield. The witness noticed that the airplane initially climbed with a high pitch attitude, but he did not observe the subsequent climbout or accident. The airplane struck the top of 50-ft-tall trees located about 1,100 ft past the departure end of the runway and came to rest about 125 ft beyond the initial tree strike. A postcrash fire ensued.

PERSONNEL INFORMATION

The pilot, age 44, held a private pilot certificate with an airplane single-engine land rating. On March 15, 2016, the pilot was issued a third-class medical certificate with no limitations. At the time of the medical examination, the pilot reported having 60 hours of total flight time with 25 hours in the last 6 months. The pilot's logbooks were not available for the investigation.

AIRCRAFT INFORMATION

The accident airplane, a Cessna 150F, was manufactured in 1966. It was powered by a Continental Motors O-200A engine, serial number 63037-6-A. On April 24, 2002, the Federal Aviation Administration (FAA) approved the use of auto gas for the airplane and engine in accordance with supplemental type certificates SE634GL and SA633. At the time of the airplane's last annual inspection on December 26, 2015, the airframe had accumulated 6,184 total hours, and the engine had accumulated 961 hours since its last overhaul.

METEOROLOGICAL INFORMATION

At 1015, the weather observation station at Edgar County Airport, Paris, Illinois, located about 21 miles west of the accident site, reported wind from 110° at 3 knots, visibility 10 miles, clear skies, temperature 24° C, dew point 13° C, and altimeter setting of 30.06 inches of mercury.

AIRPORT INFORMATION

IN46 was a privately owned, uncontrolled airport, located in a rural area 2 miles south of Rockville, Indiana. The airport elevation was 687 ft mean sea level, and the grass runway, oriented in a 09/27 configuration, was 2,081 ft long and 65 ft wide. The runway was dry and in good condition at the time of the accident. When using runway 27, a 20-to-1 slope was required to clear trees 500 ft beyond the departure end.

WRECKAGE AND IMPACT INFORMATION

The wreckage was located about 1,100 ft beyond the departure end of runway 27 slightly right of the projected runway centerline. Damage was observed to the tops of trees about 125 ft preceding the wreckage location, and broken branches were found below these trees. Broken tree branches were consistent with the airplane descending through the trees at an angle of about 70°. No damage was noted to terrain outside of the immediate footprint of the airplane, which came to rest upright and aligned with the runway heading.

The cabin area of the fuselage was destroyed by fire, but the tail section was mostly intact and undamaged by fire. Damage to both wing leading edges was consistent with tree and branch impact. One of the propeller's blade tips was bent forward at a 90° angle, and the other blade was bent aft and embedded in the ground.

Examination of the airplane revealed normal flight control continuity, and no anomalies of the flight control surfaces were noted. The flaps actuator indicated that the flaps were in the "up" position and that the elevator trim was near the "neutral" position. All cockpit engine controls were fire damaged, and the throttle was observed in the "full open" position.

The engine was removed for further examination, and the carburetor was disassembled, and no anomalies were noted except for thermal damage. The throttle and mixture control arms moved freely by hand, and the accelerator pump actuated normally.

The top spark plugs were removed, and the electrodes exhibited normal signatures. The cylinder combustion chambers were examined with a lighted borescope, and no anomalies were noted. The propeller was rotated by hand, and engine continuity was confirmed with thumb compression obtained on all four cylinders. The magnetos and ignition harness were thermally damaged, and the magnetos did not produce spark.

Examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.

MEDICAL AND PATHOLOGICAL INFORMATION

The Terre Haute Regional Hospital Department of Pathology conducted an autopsy on the pilot. The autopsy report noted the cause of death was "blunt force injuries." The FAA's Civil Aerospace Medical Institute performed toxicology tests on the pilot's specimens, and the results were negative for tested drugs.

TESTS AND RESEARCH

Weight and Balance Calculations

Based on the pilot's medical certificate weight, the passenger's driver's license weight, and a full fuel load of 26 gallons, the airplane's takeoff weight would have been 45 lbs above its maximum gross weight. Although a witness observed the pilot add fuel to the airplane with plastic jugs from his car trunk, the investigation was unable to determine the actual amount of fuel onboard the airplane during the takeoff.

Based on the Pilot's Operating Handbook performance chart, at maximum gross weight and 24° C with no wind, 1,500 ft of runway would have been needed to clear a 50-ft-high obstacle. The chart did not contain a correction for a grass runway.

Applicable Guidance

The FAA Airplane Flying Handbook (FAA-H-8083-3B, Chapter 5) describes ground effect as follows:

Ground effect is a condition of improved performance encountered when the airplane is operating very close to the ground. Ground effect can be detected and measured up to an altitude equal to one wingspan above the surface. When the wing is under the influence of ground effect, there is a reduction in upwash, downwash, and wingtip vortices. As a result of the reduced wingtip vortices, induced drag is reduced.

Due to the reduced drag in ground effect, the airplane may seem to be able to take off below the recommended airspeed. However, as the airplane rises out of ground effect with an insufficient airspeed, initial climb performance may prove to be marginal because of the increased drag. Under conditions of high-density altitude, high temperature, and/or maximum gross weight, the airplane may be able to become airborne at an insufficient airspeed, but unable to climb out of ground effect. Consequently, the airplane may not be able to clear obstructions.

The FAA Airplane Flying Handbook contains the following information about a soft-field takeoff:

After becoming airborne, the nose should be lowered very gently with the wheels clear of the surface to allow the airplane to accelerate to Vy, or Vx if obstacles must be cleared. Extreme care must be exercised immediately after the airplane becomes airborne and while it accelerates, to avoid settling back onto the surface. An attempt to climb prematurely or too steeply may cause the airplane to settle back to the surface as a result of losing the benefit of ground effect. An attempt to climb out of ground effect before sufficient climb airspeed is attained may result in the airplane being unable to climb further as the ground effect area is transited, even with full power. Therefore, it is essential that the airplane remain in ground effect until at least Vx is reached.

NTSB Probable Cause

The pilot's use of an improper soft-field takeoff procedure, which resulted in the airplane having insufficient airspeed to climb out of ground effect and its subsequent impact with trees near the departure end of the runway.