N7337JPiper PA-28-140 · 1968

On November 6, 2012, about 1220 central standard time, a Piper PA-28-140 airplane, N7337J, impacted terrain near Anadarko, Oklahoma. The private pilot, the sole occupant, was fatally injured. The airplane was substantially damaged and a post-crash fire ensured. The airplane was registered to and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the flight that operated on a visual flight rules flight plan. The flight departed the Crosbyton Municipal Airport (8F3), Crosbyton, Texas, at 1207, and was destined to the Anadarko Municipal Airport (F68), Anadarko, Oklahoma.

According to statements provided by witnesses, the airplane was seen approaching the airfield from the north and landed at an angle about one-quarter of the way down runway 17. The airplane drifted to the left and airplane’s left main landing gear went off the runway into the dirt. The airplane then climbed, turned left, and circled over the airport to enter the downwind leg for a left base turn to runway 35. As the airplane turned to land on runway 35, the airplane's bank increased to the point where the top of the airplane was completely visible to the eyewitness. The airplane subsequently made a rapid descent towards the terrain.

The pilot, age 62, held a private pilot certificate with a single engine land rating. He was issued a third class medical certificate on April 5, 2011, with the restriction that he must have glasses available for near vision. The pilot had been issued his private pilot’s certificate on April 5, 2011. The pilot’s log book was not recovered during the course of the investigation, and the pilot’s complete flight experience is unknown.

The single engine, low wing, fixed landing gear equipped airplane, N7337T, was manufactured in 1968. It was registered with the Federal Aviation Administration under the normal and utility classifications. A review of the log books found that the previous annual inspection accomplished on February 7, 2012, noted an airframe total time of 3,986.88 hours and an engine total time of 3,986.88 hours, with 1,476.28 hours since major overhaul. A log book entry for work accomplished on the right flap was accomplished on August 10, 2012, with an airframe total time of 4,033.5 hours.

At 1215, an automated weather reporting facility located at Chickasha Regional Airport (KCHK), Chickasha, Oklahoma, located 15 nautical east of the accident site reported wind from 260 degrees at 5 knots, visibility 10 miles, a clear sky, temperature 68 degrees Fahrenheit (F), dew point 43 degrees F, and a barometric pressure of 30.10 inches of mercury.

The prevailing wind was from the west, and the traffic pattern was flown to the west. Without compensating for wind, the airplane could be susceptible to overshooting final approach.

The accident occurred while the airplane was attempting to land at F68. F68 is a non-towered, publicly owned airport. The only runway available is 17/35, which is asphalt paved and is 3,100 feet long, and 50 feet wide. The airfield does not have its own weather reporting station, so pilots must either utilize the weather reporting station at KCHK or utilize the windsock located near the approach end of runway 17.

The airplane impacted an open, farm field about 0.4 miles south-southwest of runway 17’s threshold. The soil was dry and appeared hard packed. The main impact point was a shallow crater. Near the crater was the airplane’s propeller which was fractured from the propeller hub. The wreckage was about 10 feet southwest of the impact point and was in the upright position. The nose of the airplane faced 170 degrees. The left wing, fuselage, vertical stabilizer, rudder, left horizontal stabilizer, and left elevator were almost totally consumed by fire. The leading edge of the right wing was crushed. The right wing tip was buckled and displaced aft and upward. The right horizontal stabilizer was heat damaged. Flight control continuity was established through cable continuity from the control surfaces to the cockpit controls. The flaps were in the retracted position. Both propeller blades displayed signatures of leading edge polished and chord wise scratches. The propeller attach bolts were found sheared. There were no preimpact anomalies detected with the airframe.

The engine was heat damaged. It was impact separated from the fuselage. The engine crankshaft rotated freely and engine continuity and compression were established. The oil screen was free of obstructions. The left magneto was heat damaged and the right magnetos produced spark at all of the terminals. The carburetor fuel inlet screen was free of obstructions. There were no preimpact anomalies detected with the engine.

An autopsy was performed on the pilot by the Office of the Chief Medical Examiner, Oklahoma City, Oklahoma. The cause of death was multiple blunt force trauma and thermal injuries. The manner of death was ruled an accident.

Forensic toxicology was completed on specimens from the pilot by the Federal Aviation Administration’s Civil Aerospace Medical Institute (CAMI), Oklahoma City, Oklahoma. The autopsy was negative for carbon monoxide, cyanide, ethanol, and screen substances. One finding was that 262 mg/dl of glucose was detected in vitreous. CAMI noted that “postmortem vitreous glucose levels about 125 mg/dl are considered abnormal…”

The pilot did not report any medical concerns on his most recent medical application or during his examination. Medical records for the pilot were not located and it is unknown what medical treatment the pilot was undergoing. The pilot’s brother was not aware of any health concerns. Although the elevated postmortem glucose level suggests that the pilot may have been diabetic, it could not be determined if the pilot was aware of his medical condition or seeking medical care.

The prevailing wind was from the west, and the traffic pattern was flown to the west. Without compensating for wind, the airplane would be subjected to an overshooting final.

Overshooting finals

An excerpt from the FAA’s “Airplane Flying Handbook,” 2004 (FAA-H-8083-3A):

Normally, it is recommended that the angle of bank not exceed a medium bank because the steeper the angle of bank, the higher the airspeed at which the airplane stalls. Since the base-to final turn is made at a relatively low altitude, it is important that a stall not occur at this point. If an extremely steep bank is needed to prevent overshooting the proper final approach path, it is advisable to discontinue the approach, go around, and plan to start the turn earlier on the next approach rather than risk a hazardous situation.

Accelerated Stalls

An excerpt from the FAA’s “Airplane Flying Handbook,” 2004:

The airplane will, however, stall at a higher indicated airspeed when excessive maneuvering loads are imposed by steep turns, pull-ups, or other abrupt changes in its flightpath. Stalls entered from such flight situations are called “accelerated maneuver stalls,” a term, which has no reference to the airspeeds involved.

Stalls which result from abrupt maneuvers tend to be more rapid, or severe, than the unaccelerated stalls, and because they occur at higher-than-normal airspeeds, and/or may occur at lower than anticipated pitch attitudes, they may be unexpected by an inexperienced pilot.

Safety Alert SA-019

March 2013, the NTSB held a general aviation safety forum. One of the safety alert issues was the prevention of aerodynamic stalls at low altitude. This alert provided recommended tools for pilots to avoid this accident potential.