Okeechobee, FL, USA
N9774L
Beech A24R
The non-instrument rated private pilot was making a night cross country flight. Radar data indicated that the airplane departed, turned on course and maintained heading for about 24 minutes. The airplane then began to turn left and rapidly descend. The last radar hit placed the airplane less than 1 mile from the accident site. Examination of the wreckage indicated the airplane broke up in flight at a low altitude; the outboard wing panels and the left half of the horizontal stabilator were found about 1,000 feet from the main wreckage. All separations displayed signatures indicative of overload. The accident occurred at night with no illumination from the moon, which was more than 15 degrees below the horizon. Satellite infrared images depicted a broken cloud layer over the accident site with cloud tops near 13,000 feet. Weather radar images showed that the accident site bordered an area of VIP Level 2 moderate intensity echoes with echo tops near 13,000 feet. This area of echoes was associated with a decaying cumulonimbus cloud (thunderstorm). The proximity of the echoes to the accident site suggests the potential for moderate intensity convectively induced turbulence. It is likely that the pilot encountered instrument meteorological conditions or at least lost all visual reference, became disoriented and lost control of the airplane.
HISTORY OF FLIGHT On April 25, 2006, about 2111 eastern daylight time, a Beech A24R, N9774L, impacted the ground following a loss of control and subsequent inflight breakup near Okeechobee, Florida. The private pilot and the passenger received fatal injuries and the airplane was destroyed. The airplane was registered to and operated by the pilot. Dark night visual meteorological conditions prevailed and no flight plan was filed for the 14 Code of Federal Regulations Part 91 personal flight from Wachula, Florida, to Fort Pierce, Florida. The flight departed from the Wauchula Municipal Airport about 2047. The pilot and passenger were returning from visiting a family member in St. Petersburg, Florida. They departed St. Petersburg and stopped for fuel at Wauchula before continuing the flight to St. Lucie County International Airport, Fort Pierce. A family member notified authorities when the flight did not arrive. Local authorities located the airplane wreckage about 2200 on April 27, 2006. Review of recorded radar data revealed that the airplane departed Wauchula to the north, turned right and headed east. The easterly heading was maintained until approximately 2111, at which time the airplane turned left to a northerly heading. The last radar hit was recorded at 2111:26 and placed the airplane less than 1 mile from the accident site. The recorded mode C altitude for the airplane's entire flight was "-1,000 feet", indicating invalid data. Estimates of the airplane's altitude were generated by the height finder feature of the radar sites. Between 2110:26 and 2111:26, the airplane's estimated altitude changed from 6,000 feet to 2,400 feet, indicating a descent rate of 3,600 feet per minute. PERSONNEL INFORMATION The pilot, age 55, held a private pilot certificate with an airplane single engine land rating issued on September 29, 2005. The pilot was not instrument rated. On the application for his private pilot certificate dated September 29, 2005, the pilot reported that he had accumulated a total flight time of 72 hours. He held a third class medical certificate dated May 18, 2005, with the limitation, must have glasses available for near vision. The flight instructor, who instructed the pilot for his private pilot certificate and provided complex training in the accident airplane, reported that he had flown between 30 to 40 hours with the pilot, including approximately 15 hours in the accident airplane. The instructor estimated that the pilot had flown about 70 to 75 hours in the accident airplane. AIRCRAFT INFORMATION The 1972 model Beech A24R Sierra was powered by a 200-horsepower Lycoming IO-360-A1B6 engine, S/N L-8493-51A. The airplane's maintenance records were recovered from the wreckage; however, they were damaged and illegible. According to the pilot's flight instructor, the pilot purchased the airplane on December 3, 2005, in Casey, Illinois. The instructor and the pilot flew the airplane from Illinois to Florida. While flying the airplane to Florida, there were no problems with the airplane except vibration of the engine during engine starting and shutdown. The instructor flew with the pilot in the airplane on April 12, 2006, on a flight to the Bahamas. During this flight, he noticed that the electric turn coordinator was inoperative. The instructor advised the pilot that the turn coordinator needed to be repaired before flying the airplane at night. After hearing of the accident, the flight instructor contacted the mechanic who maintained the airplane and asked him if the turn coordinator had been repaired. The mechanic indicated that he was not aware of this discrepancy with the airplane and had not corrected it. METEOROLOGICAL INFORMATION The closest official NWS weather observation station that was reporting surrounding the time of the accident was at Orlando International Airport (KMCO) located approximately 59 miles north of the accident site, at an elevation of 96 feet msl. Orlando weather at 2053, wind from 260 degrees at 5 knots, visibility unrestricted at 10 miles, a few clouds at 8,000 feet agl, temperature 28 degrees Celsius (C), dew point 18 degrees C, altimeter 29.93 inches of Mercury (Hg). Orlando weather at 2153, wind from 280 degrees at 6 knots, visibility unrestricted at 10 miles, ceiling broken at 10,000 feet agl, temperature 27 degrees C, dew point 18 degrees C, altimeter 29.96 inches of Hg. Geostationary Operations Environmental Satellite number 12 (GOES-12) visible and infrared images surrounding the time of the accident from 2000 through 2200 were reviewed. The GOES-12 infrared image at 2132 depicts a band of low to mid-level clouds extending over southern Florida that obscures the accident site. No defined cumulonimbus clouds with any temperature enhancement were noted in the vicinity of the accident site. Two areas of decaying cumulonimbus to cumulus congestus clouds were identified to the north between the accident site and Orlando and to the southeast with an area north of West Palm Beach, with an area of brighter echoes. The radiative cloud top temperature over the accident site was observed at 277.60 degrees Kelvin or 4.44 degrees C, which indicated cloud tops in the range of 13,000 feet. The closest NWS Weather Surveillance Radar-1988, Doppler (WSR-88D) was located at Melbourne (KMLB), approximately 45 miles east-northeast of the accident site. The radar produces three basic types of products reflectivity, radial velocity, and spectral width. Reflectivity is normally displayed in decibels (dBZ) and is a general measure of echo intensity. The FAA Advisory Circular AC 00-24B titled "Thunderstorms" dated January 2, 1983, also defines the echo intensity levels and potential weather phenomena associated with those levels. If the maximum VIP Level is 1 "weak" and 2 "moderate", then light to moderate turbulence is possible with lightning. VIP Level 3 is "strong" and severe turbulence is possible with lightning. VIP Level 4 is "very heavy" and severe turbulence is likely with lightning. VIP Level 5 is "intense" with severe turbulence, lightning, hail likely, and organized surface wind gusts. VIP Level 6 is "extreme" with severe turbulence, lightning, large hail, extensive surface wind gusts and turbulence. The KMLB WSR-88D base reflectivity image for the 0.5 degree elevation scan completed at 2129 depicts very light reflectivity echoes over southeastern Florida, with a few isolated embedded cells with reflectivities reaching approximately 44 dBZ or VIP Level 3 "strong" intensity echoes. The accident site was located in an area of echoes in the range of 5 to 10 dBZ, which were associated with Bragg scattering, which implies scattering by refractive index gradients along the peripheries of cumulus clouds. An echo near 35 dBZ, a VIP Level 2 "moderate" intensity echo, was located immediately east of the accident (within 1 mile). The echo immediately east of the accident site had a decreasing intensity trend, with the echo having been as strong as 50 dBZ or VIP Level 5 "intense" at 2106. The KMLB WSR-88D 1.4 degree base reflectivity elevation scan completed at 2130 shows the accident site is free of any echoes, but borders an echo of 20 to 25 dBZ. The echo was also identified up to the 3.4 degree scan, indicating an echo top reaching approximately 13,000 feet. The United States Naval Observatory astronomical data for Okeechobee, Florida on April 25, 2006, was as follows: Sunset at 1953 End of civil twilight at 2018 Elevation of Sun: more than 15 degrees below the horizon Moonset at 1751 Elevation of Moon: more than 15 degrees below the horizon Moon phase: waning crescent with 6% of the moon's visible disk illuminated WRECKAGE AND IMPACT INFORMATION Examination of the accident site showed the airplane was inverted with the forward and roof sections crushed. The airplane's engine with the propeller still attached was inverted and partially buried in a crater adjacent to the firewall. The left and right outer wing panels, left and right ailerons, and the left half of the horizontal stabilator were located about 1,000 feet northeast of the main wreckage. Examination of the wreckage revealed that both outer wing panels separated in an upward direction at the wing skin splices outboard of the wheel wells. The right wing panel had collision damage on its trailing edge at a mid-span location. The left wing panel had no visible collision damage. The right half of the stabilator had collision damage on its leading edge and remained partially attached to the fuselage. The left half of the stabilator had no visible collision damage. Control continuity was verified for all flight controls, except for separations to the aileron controls related to separation of the outer wing panels. The engine sustained heavy impact damage; there were multiple cracks in the crankcase, and the oil sump was fragmented. Impact damage prevented rotation of the engine crankshaft. The rear accessory case was removed, and the internal drive gears were found intact. Bore scope examination of the cylinders revealed no anomalies. Continuity of the reciprocating components within the power section and accessory section was confirmed visually through openings in the crankcase and by means of bore scope. The vacuum pump received impact damage and the pump rotor was crushed. The pump coupler was intact. The propeller remained attached to the engine crankshaft. Both propeller blades displayed light chordwise abrasions. Upon completion of the wreckage examination, the NTSB investigator-in-charge (IIC) retained the artificial horizon, the propeller and a handheld Garmin GPS 296 unit for further examination. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy of the pilot was conducted by the District 19 Medical Examiner Office, Fort Pierce, Florida. The cause of death was reported as multiple injuries due to blunt trauma. Toxicology tests were conducted by the FAA's Toxicology and Accident Research Laboratory. The tests were negative for drugs. Ethanol was detected in liver and muscle; however, the report noted that the specimens were putrefied. Tests for carbon monoxide and cyanide were not performed. TESTS AND RESEARCH The Garmin GPS 296 that was recovered from the wreckage was sent to the manufacturer for data extraction. According to the manufacturer, the unit had sustained significant physical impact damage, and all attempts to power the unit were unsuccessful. It was not possible to extract any data from the unit. The artificial horizon was disassembled by the NTSB investigator-in-charge (IIC) and slight to light scoring of the rotor was found. The propeller was disassembled under the supervision of the NTSB IIC. No evidence of any pre-impact discrepancies was found during the disassembly.
The pilot's failure to maintain aircraft control as a result of spatial disorientation and an in-flight break up. Contributing to the accident were the dark night and thunderstorms.
Source: NTSB Aviation Accident Database
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