Aviation Accident Summaries

Aviation Accident Summary WPR11FA021

Agua Dulce, CA, USA

Aircraft #1

N427MC

CIRRUS DESIGN CORP SR-22

Analysis

The airplane departed the airport and flew in a northerly direction towards the mountain pass that was along the airplane's planned route of flight to the northeast. About 12 minutes later, the airplane entered an uncontrolled descent and impacted mountainous terrain at an elevation of 2,690 feet mean sea level (msl). Witnesses reported hearing the airplane overhead moments before the crash, but could not see it through the low clouds, fog, and mist that enveloped the area. The weather at the departing airport (elevation 802 feet) included a broken cloud layer at 1,800 feet and an overcast layer at 2,800 feet. The highest elevation of the mountain pass was 3,200 feet msl with mountain peaks on either side of the pass rising between 4,000 and 5,000 feet. Weather at the accident site at the time was estimated to have been overcast from 3,200 feet (500 feet above ground level) to 4,700 feet. The weather at the nearest airport, which was also next on the airplane's route of flight, 15 miles to the northeast of the mountain pass, had excellent visibility and clear skies. The private pilot did not have an instrument rating. Ethanol was identified in tissue samples obtained from the pilot; however, the toxicology testing could not reliably determine if the ethanol was produced post-mortem or through ingestion. Postaccident examination of the airframe and engine found no preimpact mechanical malfunctions or failures that would have precluded normal operation. Witness reports and findings from the wreckage examination are consistent with a loss of control event; and based on the degraded visual reference conditions present about the time of the accident it is likely that the pilot experienced spatial disorientation.

Factual Information

HISTORY OF FLIGHT On October 21, 2010, at 1210 Pacific daylight time, a Cirrus SR-22, N427MC, impacted a horse stable in mountainous terrain, 1.5 miles west of the Agua Dulce Airport, Agua Dulce, California. The owner operated the airplane under the provisions of Title 14 Code of Federal Regulations Part 91. The private pilot and his two passengers were fatally injured, and the airplane was substantially damaged. The airframe was severely fragmented and consumed by a post impact fire. Instrument meteorological conditions prevailed, and no flight plan had been filed. The flight originated at Van Nuys, California, about 1156. Radar data indicated that the airplane departed Van Nuys Airport at 1156:45 initially to the south, then turned to the north, and climbed to 1,500 feet mean sea level (msl). Van Nuys tower requested a (cloud) base report from the pilot. The pilot reported before he switched off frequency that there were few clouds at 2,300 feet msl, and the layer above that was between 3,500 and 3,800 feet msl. The radar track shows that the airplane leveled off at 1,500 feet msl for 2 minutes, climbed to approximately 3,300 feet momentarily, then descended to approximately 2,200 feet. The final radar return was at 1202:04 at 2,200 feet, 11.6 miles southwest of the accident site. Witnesses reported that they heard the airplane overhead in the vicinity of the Agua Dulce Airport, but could not see it due to low clouds, fog, and mist. One witness stated that seconds before the airplane impacted terrain it overflew her upside down. Two witnesses working on a nearby roof top said they observed the airplane flying very low, pass between two hills north of the accident site, then make a steep right-hand descending turn and impacted the ground "like a missile." They said the engine pitch increased slightly while behind the hill, and then was steady in pitch until the airplane impacted the ground. The pilot's wife said that the purpose of the flight was to travel to Parker, Arizona. The pilot had called her prior to departing Van Nuys, and told her that he intended to fly from Van Nuys, over Agua Dulce, to Palmdale, over to the Cajon Pass, and then direct to Parker. The terrain between Van Nuys and Palmdale consists of mountainous terrain (Angeles National Forest) with ridgelines between 4,000 feet and 5,000 feet msl to the north and south of the Antelope Valley Freeway. The Antelope Valley Freeway (CA-14) passes through the Angeles National Forest from southwest to northeast and the highest elevation is about 3,200 feet msl, near Agua Dulce. The airplane wreckage was contained in a compact area about 40 feet in diameter and located in a horse corral. As a result from the ground impact, three horses were fatally injured, and corral structures exhibited soot and fire damage. PERSONNEL INFORMATION The pilot, age 51, held a private pilot certificate for airplane single-engine land issued June 2, 2004, and a third-class medical certificate issued October 21, 2010, with the limitation that the pilot must have glasses available for near vision. Portions of the pilot's logbook were recovered and examined; the majority of the logbook had been destroyed by fire. The pilot's logbook contained an endorsement for a flight review on June 28, 2008. On the pilot's October 21, 2010, medical application he reported having 285 hours of total pilot time, and accumulated 45 hours within the previous 6 months. AIRCRAFT INFORMATION The four seat, low-wing, fixed gear airplane, serial number 0152, was manufactured in 2002. It was powered by a Teledyne Continental Motors IO-550-N, 310-hp engine and equipped with a 3-bladed constant speed Hartzell propeller. Review of the maintenance logbook showed an annual inspection was completed May 2, 2010, at a recorded Hobbs time and total aircraft time of 827.4 hours. Neither the engine tachometer nor the Hobbs meter was recovered from the aircraft wreckage, therefore, the actual time on the airplane at the time of the accident was not determined. METEROLOGICAL INFORMATION A Citizen Weather Observers Program station at Agua Dulce was located about 1.4 miles to the east of the accident site at an elevation of 2,592 feet. Data from this station indicated that wind speeds were relatively light and relative humilities were in the low 90's (%) during the times surrounding the accident. Determining a cloudy area based on relative humidity values alone can be relatively difficult. While values close to 100% (greater than 95%) are safe in defining cloudy thresholds, values below 90% have been observed at cloud boundaries. The closest surface reporting station with visibility and ceiling detection capabilities was Palmdale Regional Airport, Palmdale, California, located at an elevation of 2,543 feet. Palmdale Airport is located approximately 15 miles to the northeast of the accident site, and was equipped with an Automated Surface Observing System (ASOS). Reports from Palmdale were issued while a certified weather observer was logged into the system. During the times surrounding the accident, the Palmdale ASOS indicated clear skies with excellent visibility. At 1153 PDT, the wind was from 210 degrees at 15 knots. The accident airplane's departure airport was Van Nuys Airport, Van Nuys, which is located at an elevation of 802 feet. Van Nuys Airport is located approximately 19 miles to the south-southwest of the accident site and was equipped with an ASOS. Reports from Van Nuys Airport were issued while a certified weather observer was logged into the system. At 1151 PDT, the airport was mostly VFR (visual flight rules) with broken ceilings at 1,800 feet above ground level (agl) and an overcast cloud base at 2,800 feet agl, visibility greater than 10 miles, and a light wind. A North American Mesoscale (NAM) model sounding for the accident location (where the surface elevation is estimated at 2,690 feet) at 1100 PDT was retrieved from NOAA's Air Resources Laboratory. The NAM model sounding indicated near-saturated conditions between about 3,175 and 4,725 feet, where relative humidity values were 97% or greater. Relative humidity values were 90% at the surface, and above the near-saturated layer, the atmosphere dried out considerably. Classifications made by the Rawinsonde Observation program (RAOB) indicated overcast clouds were likely preset in the near saturated layer, with bases within about 500 above the surface. The wind at the surface was 7 knots from the southwest, and the NAM model data indicated the wind rotated clockwise with height and had magnitudes approaching 20 knots from the northwest above 6,000 feet. A camera image taken by one of the accident passengers after departure and prior to reaching Agua Dulce was examined. The exact location and altitude of the airplane at the time this image was captured is estimated to be about 5 miles north of the Van Nuys Airport. The image does indicate a ceiling that partially obscures the tops of terrain in front of the airplane. A Los Angeles Police Department (LAPD) helicopter pilot, who was operating in the area near the time of the accident, indicated conditions would have made it impossible to fly beneath the clouds in the area of the accident. The LAPD pilot indicated that clouds obscured the hill tops to the north of the accident site and that conditions there were basically 0/0 (zero visibility and ceiling at surface). Numerous AIRMETs (Notice for Airmen) for IFR (instrument flight rules), mountain obscuration and icing conditions were active over southern California during the time of the accident. At the time of the accident, an AIRMET for mountain obscuration, which advised of mountains obscured by clouds, was active for the accident location. Several AIRMETs for IFR conditions was also active near the accident site. The entire Meteorological Weather Study is contained in the official docket of this investigation. WRECKAGE AND IMPACT INFORMATION Los Angeles County Fire received the call of an airplane crash and fire at 1219. The wreckage was located at an elevation of 2,690 feet msl, in a residential horse stable, and had impacted on level ground and corral fencing 15 feet from a wooden stable structure. The airplane wreckage had experienced an extreme post impact fire, consuming much of the airplane structure, leaving only carbon fiber cloth material and wing spar structure. The magnetic bearing taken from the engine and directed back towards the flight path perpendicular to the wing spars, was 110 degrees magnetic. Examination of the airframe revealed that all control surfaces were present and control continuity was confirmed through cable connections to control bell cranks or overload failure signatures. The airframe parachute system was located within the wreckage, the rocket motor case was located next to the engine with propellant expended, the parachute was in the stowed configuration, and exhibited thermal damage. Neither the parachute activation handle nor the safety pin was identified in the wreckage. The engine was imbedded into the ground about 2 feet, and was removed using a hoist. Fuel odor was evident as the engine was lifted, and dark oil like fluid drained from the engine. Cylinders 1, 3, and 5 had impact damage and the forward end of the engine case was fragmented. The oil pan had been crushed up into the engine case. The exhaust manifold exhibited bends and folds consistent with plastic deformation. The two magnetos were not present on their respective mounting pads. The propeller had been separated from the engine, but was located in the ground in line with the engine crankshaft. The propeller was removed from the earth using a hoist. All three blade shanks were in the propeller hub, two blades were present in the hub, and the third blade had fractured at the shank end. Blades exhibited leading edge polishing and sinusoidal s-bending. Post accident examination of the airframe and engine found no preimpact mechanical malfunctions or failures that would have precluded normal operation. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed on the pilot October 26, 2010, by the Los Angeles County Coroner, Los Angeles, California. The autopsy findings specified the cause of death as multiple blunt force injuries. Forensic toxicology was performed on specimens from the pilot by the FAA Bioaeronautical Sciences Research Laboratory CAMI, Oklahoma City, Oklahoma. The toxicology report stated tests for carbon monoxide and cyanide were not performed. Volatiles detected were 78 mg/dL of ethanol detected in the kidney, 27 mg/dL ethanol detected in lung, 18 mg/dL ethanol detected in muscle, 0.044 ug/ml codeine were detected in kidney, and codeine detected in lung.

Probable Cause and Findings

The non-instrument-rated pilot's improper decision to continue the flight into instrument meteorological conditions, which resulted in spatial disorientation and loss of control.

 

Source: NTSB Aviation Accident Database

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