N7471PPiper PA-24-250 · 1961

On October 4, 2009, about 0725 mountain standard time, a Piper PA-24-250 airplane, N7471P, was substantially damaged when it collided with terrain near Black Canyon City, Arizona. The airplane was registered to Chief LLC of Aguila, Arizona, and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91. The airline transport pilot and his sole passenger were killed. General visual meteorological conditions prevailed along the route and no flight plan was filed for the personal flight. The cross-country flight originated from the St. John's Industrial Airport, St. Johns, Arizona, at 0600, with an intended destination of Aguila, Arizona.

A family member of the pilot reported the airplane overdue to the Federal Aviation Administration (FAA) on the morning of October 5, 2009, after becoming concerned when the airplane and pilot had not arrived at their intended destination. The FAA subsequently issued an Alert Notification (ALNOT). On the afternoon of October 5, United States Forest Service (USFS) firefighters reported locating the wreckage of a downed airplane while fighting a wildfire around the 5,499 foot level of the Bradshaw Mountain Range near the accident site. USFS personnel reported that the fire in the area was initially reported about 1600 on October 4, 2009.

Review of radar data supplied by the FAA revealed that about 50 miles east of the accident site, the flight was at a pressure altitude of 8,500 feet mean sea level (msl), with a flight path predominately on west-southwest heading. The radar data depicted a descent from a pressure altitude of 6,900 feet at 0723 to 5,700 feet at 0725, where radar contact was lost. During this descent, the data shows a slight turn to the left followed by a slight right turn. The last radar target was located about 0.32 miles southeast of the accident site, at a pressure altitude of 5,700 feet msl.

Review of recorded radio communications between the pilot and the Albuquerque Air Route Traffic Control Center (ARTCC) revealed that at 0700, the pilot informed the controller that he was “going to be drifting down just a little bit lower to stay under the clouds." At 0716, the controller provided the pilot with a frequency change to a different sector. The pilot confirmed the transmission and subsequently contacted the new sector controller at 0717. Upon initial contact with the pilot, the controller provided the pilot with an updated altimeter setting of 29.67, followed by a confirmation from the pilot. No further radio communication was received from the pilot. In addition, no emergency distress calls were received from the pilot.

The pilot, age 74, held an airline transport pilot certificate with airplane multiengine land ratings. The pilot also held a commercial pilot certificate with airplane single-engine land and airplane single-engine sea ratings. A third-class airman medical certificate was issued on October 10, 2008, with the limitation stated "must have available glasses for near vision." The pilot's logbook was not recovered for examination. The pilot reported on his most recent medical certificate application they had accumulated 22,239 total flight hours.

The four-seat, low-wing, retractable-gear airplane, serial number (S/N) 24-2662, was manufactured in 1961. It was powered by a Lycoming O-540-A1D5 engine, serial number L-4053-40 and equipped with a Hartzell model HC-A2MVK-1, serial number HXA23, variable-pitch propeller.

Review of copies of maintenance logbook records showed an annual inspection was completed October 1, 2009, at a recorded tachometer reading of 2,649.03 hours, airframe total time of 2,649.03 hours, and engine time since major overhaul of 527.16 hours. The tachometer was observed at the accident site; however, damage precluded determining the current readings.

A National Transportation Safety Board (NTSB) staff meteorologist prepared a factual report for the area surrounding the accident site.

The National Weather Service (NWS) Surface Analysis Chart depicted a trough of low pressure over western Arizona with southerly winds of 10 to 20 knots ahead of the trough with scattered to broken clouds over the state.

The NWS Radar Summary Chart issued for the hour at 0740 depicted an area of light rain showers over central Arizona in the vicinity of the accident site, with echo tops from 18,000 to 20,000 feet. No movement was provided with the area of echoes. NWS composite radar image at 0725 for the area centered over Arizona and the accident site. Reflectivity values of 10 to 35 dBZ were observed in the vicinity of the accident site.

The closest weather reporting facility to the accident site was from Humbug Creek (QHBA3), an unmanned Remote Automated Weather Station (RAWS) site at an elevation of 5,250 feet mean sea level (msl) located approximately 3 miles west of the accident site. The Humbug RAWS weather site recorded at 0648, wind from 216 degrees at 22 knots gusting to 31 knots, temperature 56 degrees Fahrenheit (F), dew point 56 degrees F, and relative humidity 100 percent. At 0748, the Humbug RAWS weather site recorded wind from 209 degrees at 23 knots gusting to 35 knots, temperature 54 degrees F, dew point 54 degrees F, and relative humidity 100 percent.

The Sunset Point (QSPA3) RAWS was located approximately 8 miles northeast of the accident site at an elevation of 2,960 feet msl, in Bumble Bee, Arizona on the western side of Interstate 17. At 0653, the Sunset Point RAWS weather site recorded wind from 039 degrees at 12 knots gusting to 17 knots, temperature 62 degrees F, dew point 56 degrees F, and a relative humidity of 81 percent.

At 0753, the Sunset Point RAWS weather site recorded wind from 022 degrees (northeast) at 10 knots gusting to 21 knots, temperature 62 degrees F, dew point 57 degrees F, and a relative humidity of 84 percent.

The next closest weather observation site was the Phoenix Deer Valley Airport (KDVT), located 28 miles south-southeast of the accident site at an elevation of 1,478 feet msl. The airport had an Automated Surface Observation System (ASOS) installed and reported southeasterly winds, visibility unrestricted, with a variable layer of clouds between 3,700 and 4,200 feet agl, or about 5,200 to 5,700 feet msl. A broken to overcast layer of clouds was reported prior to and after the time of the accident.

The Ernest A. Love Field Airport (KPRC), was located 7 miles north of the city of Prescott, and approximately 32 miles north-northwest of the accident site at an elevation of 5,045 feet msl. The airport was equipped with an ASOS and reported the following conditions surrounding the area at 0708: wind from 170 degrees at 12 knots gusting to 21 knots, visibility 10 miles, broken clouds at 2,700 feet agl, broken clouds at 3,700 feet, and broken clouds at 5,500 feet, temperature 49 degrees Celsius (C), dew point 9 degrees C, and altimeter 29.76 inches of Mercury (Hg).

The next closest weather reporting location was from Luke Air Force base (KLUF), approximately 7 miles west of the city of Glendale and 37 miles south-southwest of the accident site at an elevation of 1,085 feet msl. The airport had an ASOS installed and reported the following conditions at 0725 MST: wind from 120 degrees at 7 knots, visibility 10 miles, broken clouds at 3,900 feet agl, temperature 23 degrees C, dew point 16 degrees C, and altimeter 29.66 inches of Hg.

Upper air soundings were obtained from the closest NWS observing location and from model data to document the conditions over the accident site. The NWS Flagstaff (KFGZ), Arizona, site number 72376, was the closest upper air sounding or rawinsonde observation (RAOB) located approximately 70 miles north-northeast of the accident site at an elevation of 7,192 feet msl. The 0500 sounding from KFGZ plotted on a standard Skew-T log P diagram utilizing RAOB software, with the observed and derived stability parameters from the surface to 500-mb, or 18,000 feet.

The sounding depicted a moist low-level environment with the lifted condensation level (LCL) or the approximate base of the clouds at 725-hPa or at 1,813 feet agl. The sounding had a relative humidity of 75 percent or more from just above the surface to approximately 13,500 feet, and suggested saturated conditions from the LCL to 13,000 feet, which resulted in a precipitable water value of 0.47 inches.

The atmosphere was characterized as being moist and conditionally unstable below the inversions and supported nimbostratus type clouds to stratocumulus. The freezing level was identified at 11,161 feet, and supported a shallow layer of icing conditions to 13,000 feet.

The sounding wind profile indicated surface wind from 170 degrees at 9 knots with the wind veering to the southwest with height. A low-level jet was identified with wind from 210 degrees at 48 knots at 9,931 feet. The mean 0 to 6 kilometer wind was from 230 degrees at 43 knots.

A model sounding utilizing the NWS North American Mesoscale 12-kilometer model (NAM12) was obtained from the Air Research Laboratory (ARL) for 0800 and was plotted on a Skew-T Log-P diagram. The sounding depicted saturated conditions from the LCL at 866-hPa or 542 feet agl (6,021 feet msl) to approximately 9,000 feet, which implied mountain obscuration conditions in the immediate vicinity of the accident site.

The wind profile depicted southerly wind veering to the southwest and increasing in speed with height. The model data indicated that at 5,518 feet the wind was estimated from 200 degrees at 30 knots. Immediately below this level, the sounding indicated a 100 percent probability of light to moderate intensity turbulence at 5,480 feet due to a vertical wind shear of 14.1 knots per 1,000 feet. The mean 0 to 6 km wind was determined to be from 240 degrees at 44 knots.

The Geostationary Operations Environmental Satellite number 12 (GOES-12) data was obtained from the National Climatic Data Center (NCDC) and displayed on the National Transportation Safety Board’s Man-computer Interactive Data Access System (McIDAS) workstation. Both visible and infrared imagery was obtained surrounding the time of the accident. The infrared imagery (band 4) at a wavelength of 10.7 microns provided a 4-kilometer (km) resolution with radiative cloud top temperatures. The visible imagery (band 1) at a wavelength of 0.65 microns provided a resolution of 1 km.

The GOES-12 visible images for 0702 and 0732 depict the accident site under a broken to overcast layer of low stratocumulus type clouds. The GOES-12 infrared imagery during the same time depicted low clouds extending over the region with a radiative cloud top temperatures of 276.0 degrees to 278.3 degrees Kelvin (K) or 2.84 degrees to 5.14 degrees C at 0702 and 0732 respectively, which corresponded to cloud tops near 10,000 feet.

The closest NWS Weather Surveillance Radar-1988, Doppler (WSR-88D) was located at Flagstaff (KFSX), approximately 58 miles northeast of the accident site. A compilation of the KFSX WSR-88D 0.5 degree base reflectivity images completed at 0715:55, 0725:39, and 0735:21, depicted an area of light to moderate intensity echoes over central Arizona in the vicinity of the accident site and along the route of flight. At 0725, echoes of 20 dBZ extended west and north of the accident site, with no echoes over the accident site at that time. Echoes of 20 dBZ and stronger typically are an indication of precipitation reaching the surface.

The pilot reports over Arizona indicated several reports of icing in clouds between the freezing level and 14,000 feet, and varied in intensity from a trace to moderate icing. There were also several reports of moderate turbulence between 8,000 to 15,000 feet, and one report of moderate to occasional severe turbulence below 5,000 feet over the Grand Canyon National Park area of northern Arizona. There were also several urgent pilot reports of low-level wind shear in the Prescott area and several reports of updrafts and downdrafts of plus or minus 400 feet per minute (fpm).

The Area Forecast (FA) is a forecast of Visual Flight Rules (VFR) clouds and weather conditions over an area as large as the size of several states. It must be used in conjunction with the AIRMET Sierra (IFR) bulletin for the same area in order to get a complete picture of the weather. The area forecast together with the AIRMET Sierra bulletin are used to determine forecast enroute weather and to interpolate conditions at airports which do not have a terminal forecast (TAF) issued. The NWS Aviation Weather Center (AWC) located in Kansas City, Missouri, issues the FA at regular intervals and issues special reports as necessary, usually in the form of an AIRMET. The region that covers Arizona is under the Salt Lake City (KSLC) regional forecast. The forecast valid for this accident was issued at 0630 MST on October 4, 2009, and was valid until 1600 MST. The forecast was as follows:

The synopsis section of the forecast indicated that the upper level low near the Nevada, Oregon, and the California border with a trough extending southward into California, coupled with the surface cold front over Utah and Nevada were the primary weather features. The forecast for northern Arizona was for scattered to broken clouds at 9,000 to 10,000 feet with tops to 15,000 feet, and, wind from the southwest at 25 knots gusting to 35 knots. After 1100 MST widely scattered light rain showers with wind from the southwest at 30 knots gusting to 50 knots.

The pilot called the Automated Flight Service Station (AFSS) prior to his departure at 0600, and asked for a standard weather briefing. The pilot indicated that he was planning on operating VFR, with a cruising altitude of 10,500 feet, departing from St. John's Airport at approximately 0700, with the planned destination of “E35”, and an en route time of one hour and thirty minutes. The pilot of N7471P did not realize he had provided the wrong destination airport identifier for the Wickenburg Municipal Airport (E25), Wickenburg, Arizona, but had in fact provided “E35,” which was Fabens Airport, Fabens, Texas.

When the AFSS briefer responded with a question regarding his planned cruising altitude, the pilot repeated “10,500 feet.” As the AFSS briefer then began to gather the weather data, he indicated that recommended cruising altitudes eastbound were odd thousands foot plus 500 feet, which is consistent with the VFR hemispheric cruising altitude rules (CFR FAR 91.159), another flag the pilot did not question. The AFSS briefer then advised that an AIRMET for mountain obscuration and instrument flight rule (IFR) conditions existed over the route which traversed southeastern Arizona, New Mexico, and western Texas, and that VFR flight was not recommended. The AFSS briefer also provided the turbulence information of the AIRMET for occasional moderate turbulence below 18,000 feet and the weather observations and forecast data for western Texas.

At the end of the briefing the AFSS briefer asked the pilot if he needed any further information. The pilot asked for the current conditions for St. John’s (KSJN), Phoenix (KPHX), and Prescott (KPRC), Arizona. The AFSS briefer then provided the information, which indicated VFR conditions prevailed at the three airports, with a forecast for strong southwesterly winds. The briefing then concluded. The pilot at no time corrected the AFSS briefer about the planned destination or cruising level.

Wreckage debris was located on the eastern side of a mountain range within rising terrain, at an elevation of 5,488 feet msl. The wreckage energy path was oriented along a 260-degree heading. Wreckage debris was contained within about 200-feet of the main wreckage.

The first identified point of contact (FIPC) was a large flat top rock. The top of the rock exhibited blue paint transfer and numerous scratches. Numerous trees were damaged about four feet beyond the FIPC. Impact impressions were observed on a large vertical rock face about 10 feet beyond the FIPC. The rock face extended upwards about 50 feet. The right wing was observed upright between the rock face and FIPC. Remains of the propeller assembly were observed about 20 feet upwards within the rock face.

The main wreckage was located about 80 feet to the left of the FIPC. The empennage was found in the inverted position. The left wing was located in an inverted position adjacent to the main wreckage.

Examination of the wreckage revealed that the left and right wings were separated from the fuselage. The center section of the fuselage was consumed by a post-impact fire. Remains of the cockpit controls, rudder pedals, and "T" bar were present. Multiple instruments and radio equipment was displaced from the cockpit area and located throughout the wreckage debris path.

The left wing was intact and exhibited thermal and impact related damage. Compression damage was noted along the span of the leading edge. The aileron and flap remained attached to their respective mounts. The right wing was intact and exhibited thermal and impact related damage. Compression damage was noted along the span of the leading edge. The aileron and flap remained attached to their respective mounts. Flight control continuity was established from the left and right ailerons to the wing roots. The cables exhibited broomstraw separation signatures consistent with tension overload.

The empennage was intact and exhibited fire damage. The horizontal stabilator remained attached via all its mounts. The vertical stabilizer and rudder were intact. Flight control continuity was established from the cockpit area aft to the rudder and stabilator. The areas of separation in the control cables were consistent with overload. The pitch trim drum was measured in apposition consistent with neutral.

The engine exhibited one cylinder and accessory displacement. Part of one cylinder was located within the wreckage debris path. The propeller was separated from the engine crankshaft. One propeller blade was separated from the propeller hub. The opposing blade remained within the propeller hub. Both propeller blades were located near the FIPC. The exhaust muffler was located displaced from the engine and situated near the FIPC. The internal cavity of the muffler exhibited light gray brown coloration and was absent of any oil residue.

The wreckage was recovered to a secure location for further examination.

The Yavapai County Medical Examiner conducted an autopsy on the pilot on October 8, 2009. The medical examiner determined that the cause of death was “blunt impact injuries.” Review of autopsy report revealed that "decomposition" was noted.

The FAA's Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma, performed toxicology tests on the pilot. According to CAMI's report, carbon monoxide, cyanide, volatiles, and drugs were tested, and had positive results for 29 (mg/dL, mg/hg) ETHANOL detected in Lung, 27 (mg/dL, mg/hg) ETHANOL detected in Liver, 27 (mg/dL, mg/hg) ETHANOL detected in Kidney, 22 (mg/dL, mg/hg) ETHANOL detected in Spleen, 18 (mg/dL, mg/hg) ETHANOL detected in Brain, 1 (mg/dL, mg/hg) N-PROPANOL detected in Lung, and 1 (mg/dL, mg/hg) N-PROPANOL detected in Brain.

Due to the two day delay in recovering the bodies, it could not be determined if the alcohol was ingested or the result of postmortem decomposition.

A post impact fire sparked a localized wild fire, which was limited to about three acres of the main wreckage. The path of the fire burn area extended from the FIPC down slope, consuming numerous trees and vegetation.

The recovered engine and airframe were examined on November 10, 2009 at the facilities of Air Transport, Phoenix, Arizona.

Examination of the recovered airframe revealed that the fuel selector valve assembly was intact. The selector valve handle was damaged. The fuel selector valve was positioned on the "LEFT AUX" fuel tank. Continuity was established throughout the valve with no obstructions noted. Two air driven gyros were recovered. One gyro remained within the attitude indicator instrument housing. The gyro was removed from the housing and disassembled. Examination of the gyro revealed no scoring on the gyro or within the gyro housing. The second gyro was located displaced from the instrumentation and found intact and undamaged. The gyro was removed from the housing and disassembled. Examination of the gyro revealed no scoring on the gyro or within the gyro housing.

No evidence of any preimpact mechanical malfunction was observed with the airframe.

Examination of the recovered engine revealed that the engine was separated from the airframe via all engine mounts. The engine exhibited severe fire and impact damage throughout. The number one cylinder was separated from the engine. The engine crankcase and accessory housing were destroyed by fire, which exposed the internal components of the engine. All internal components visually appeared to be intact and undamaged. No evidence of heat distress or damage was observed on any of the internal reciprocating components. All connecting rods remained attached at their respective crankshaft journals. The crankshaft gear cluster, dowel, and bolt were intact and secure. The camshaft was intact. All of the camshaft lobes exhibited normal wear and displayed no evidence of spalling. The number one, two, three, four, and five cylinders were examined internally using a lighted borescope. All intake and exhaust valves were intact. No evidence of foreign object ingestion or detonation was observed. The top spark plugs were free of mechanical damage at the electrodes and displayed varying colorations from the post-impact fire.

The left magneto was destroyed by fire. The right magneto remained attached to its mount pad and was destroyed by fire. The propeller governor and mounting pad was separated from the engine. The governor exhibited impact damage. The carburetor was displaced from the engine and fractured into multiple pieces. The carburetor finger screen housing was recovered and examined. The fuel finger screen was free of debris.

The starter and alternator were separated from the engine. The oil filter was destroyed by fire. The vacuum pump was fragmented and separated from the engine. The vacuum pump housing shroud was recovered and exhibited no scoring within the internal area. The internal components of the vacuum pump were not located.

The propeller was separated from the crankshaft propeller flange. The attachment bolts were sheered at the propeller mounting flange. The two-bladed propeller assembly was labeled "A" and "B" for documentation purposes. Propeller blade A was separated from the propeller hub and exhibited thermal discoloration and damage. Approximately 8 inches of the propeller blade tip was separated. The propeller blade exhibited trailing edge and leading edge gouging along with twisting opposite the direction of rotation. Propeller blade B was partially attached to the propeller hub assembly and exhibited thermal discoloration and damage. The outboard tip of the propeller blade was separated. Chordwise scratching was observed near the remaining outboard portion of the blade. The propeller blade exhibited twisting opposite the direction of rotation and "S" bending.

No evidence of any preimpact mechanical malfunction was observed with the recovered engine.