CEN14FA328

The pilot’s inability to maintain a climb while maneuvering the airplane in high-density altitude conditions that degraded the airplane’s climb performance and his exceedance of the airplane’s critical angle-of-attack, which led to an aerodynamic stall and loss of control. Contributing to the accident was the pilot’s inadequate preflight planning and his decision to fly into mountainous terrain.

A customer service manager at the fixed-base operator (FBO) reported that the pilot, who was preparing for the cross-country flight, was looking for information on how to fly over the mountains. At that time, there was no one at the FBO who could provide him information on mountain flying, and no posted information was available. She later heard that the pilot planned to take off under visual flight rules and fly through the mountains along the interstate. Radar data showed that the airplane took off to the west, turned south, and then climbed to about 10,400 ft mean sea level (msl). Once the airplane reached the interstate, it turned west toward the mountains and followed the interstate. About 25 minutes after taking off, when the airplane was at 10,200 ft msl, radar contact with the airplane was lost. Witnesses near the accident site were consistent with their accounts, which indicated that the airplane was flying between about 11,000 and 11,500 ft msl (200 to 300 ft above the ground) with the engine producing power. The airplane was in a nose-high attitude when it started turning left away from rising terrain. The airplane then turned about 180 degrees, rolled over to the left, and entered a steep dive before impacting trees and terrain. One of the witnesses indicated that, before the left turn, the airplane's path seemed pretty flat with little gain in altitude. A postimpact fire ensued, which consumed most of the airplane. A postaccident examination confirmed flight control continuity and revealed no preimpact anomalies with the engine or airplane systems that would have precluded normal operation. The pilot did not use any weather or flight planning services. No evidence was found that the pilot had obtained training in mountain flying. A weather model determined that, at the time of the accident, the density altitude was about 12,850 ft, which would have reduced the airplane's climb rate by more than 90 percent. It is likely that, as the pilot attempted to cross over the mountainous terrain, he raised the airplane's nose such that the airplane was beyond its critical angle-of-attack, which, combined with the airplane's decreased climb performance, led to an aerodynamic stall and loss of control.

The airplane wreckage, engine, and propeller were examined at Greeley, Colorado, on July 14, 2014. An examination of the airframe wreckage confirmed continuity from the flap handle to the flaps; however, the position of the flaps could not be determined. An examination of the elevator trim cable determined the trim was at the neutral position. The fuel selector handle and valve were examined; however, the tank position selection could not be determined due to the extensive thermal damage. The engine crankshaft and camshaft rotated freely. All valves and pistons moved freely. All cylinders showed good compression. A borescope examination of the cylinders showed no anomalies. Both magnetos were removed and examined. The magnetos' couplers could not be tested due to the extensive thermal damage. The oil screen was removed and examined and was clean. The fuel pump, air filter, and vacuum pump showed extensive thermal damage. The carburetor body showed extensive thermal damage, and the floats were bent and broken. The propeller was removed from the engine's flange and disassembled. Blade A showed torsional bending, chordwise scratches, and leading edge gouges. The outer 4 inches of the blade tip was broken in overload. The blade pitch knob was sheared off. Blade B was straight and showed nicks along the leading edge. The outer 9 inches of the blade was bent aft 90 degrees. On July 2, 2014, Lockheed Martin flight service (LMFS) was contacted to determine if the pilot received any services or filed a flight plan. LMFS responded that neither it nor the Data Transformation Corporation Direct User Access Terminal Service (DUATS) provided any services to the accident pilot. Further, the Computer Science Corporation DUATS did not provide weather information to the pilot. Fuel Testing A fuel sample from the BJC fixed-base operator self-serve pump from which the pilot fueled his airplane just before the flight was secured and tested. The test results indicated the fuel was good and showed no presence of water or contaminants. Density Altitude FAA Pamphlet FAA-P-8740-2 (2008) "Density Altitude" defines density altitude as "pressure altitude corrected for non-standard temperature variations." Density altitude can affect aircraft performance. As density altitude increases, air density decreases, which results in decreased aircraft performance. According to the Koch chart on page 3 of the pamphlet, based on the conditions at the time of the accident, 59 degrees F and pressure altitude of about 11,645 ft, the airplane's climb rate would have been reduced by more than 90 percent. The results of an autopsy performed on the pilot on July 3, 2014 by the Jefferson County Coroner's Office, Golden, Colorado, showed cause of death due to loss of blood secondary to laceration-transection of the aorta related to blunt force trauma sustained in the accident. The FAA's Civil Aerospace Medical Institute performed forensic toxicology on specimens from the pilot. Test results were negative for all tests conducted. The accident site was located on the side of a mountain slope at an elevation of 11,645 ft msl. The airplane wreckage was spread along a 186 ft-long down-sloping path through a forest of Subalpine fir trees on a 246-degree magnetic heading. The elevation where the main wreckage was at was 10,960 ft. The first point of impact was a Subalpine fir tree that was broken off about 69 ft above the ground. The airplane's left wing tip, two sections of the left outboard wing, and the left aileron were found about 45 ft west-southwest of the first impact point resting on the ground, and they were crushed and broken aft at mid-span. Pieces of cut wood, broken branches, Fiberglas, and paint chips were scattered across the ground beginning at the first point of impact and running along the accident site heading for about 147 ft. Several pieces of cut wood showed a cut angle of 45 degrees with black paint transfer in the wood fibers along the cut edge. The terrain from the first point of impact to where the airplane's main wreckage came to rest was down-sloping at an angle of about 18 degrees. The main wreckage, which consisted of the airplane's engine, propeller, cabin, right wing, left inboard wing, both main landing gear, baggage compartment, aft fuselage, and empennage rested inverted at the base of four Subalpine fir trees. These components were charred, melted, and consumed by fire. A burned area about 75 ft long and 54 ft wide surrounded the main wreckage. Several trees knocked down by the airplane were also located in the burned area. Continuity from the control yokes and rudder pedals to the aileron bellcranks, stabilator crosstube, and rudder horns was confirmed at the accident site. The right aileron control surface was charred and melted. The rudder and stabilator surfaces were consumed by fire. The airplane wreckage was retained for further examination. At 0853, the routine aviation weather report for Centennial Airport, about 47 miles east of the accident site, was wind 120 degrees at 6 knots, 10 miles visibility, scattered clouds at 2,300 ft, temperature 78 degrees F, dew point 39 degrees F, and altimeter 30.03 inches of mercury. At 0851, the weather station for Keystone and Last Chance, Colorado, 4 miles southwest of the accident site, reported winds from the southwest at 1 mph, gusts to 7 mph, temperature 59 degrees F, dew point 32 degrees F, humidity 36 percent, and altimeter 29.78 inches of mercury. A weather model that produces estimates of the atmosphere was used for the accident area to determine density altitude, potential turbulence, and updrafts and downdrafts. Based on model temperature and dew point, and surface pressure for the surface location of the accident, 11,645 ft msl, the density altitude would be approximately 12,850 ft msl. Surface observations for wind at the accident site were approximately 15 knots. However, about 2,000 ft above the mountain peaks in the Loveland Pass area, the wind velocity increased to 30 to 40 knots. Aircraft-scale turbulence existed in the area within 2,000 ft of the terrain, and maximum updraft speeds of 300 to 500 ft per minute and maximum downdraft speeds of 300 to 400 ft per minute existed near the accident site. The pilot, age 42, held a private pilot certificate with an airplane single-engine land rating. According to the pilot's Federal Aviation Administration (FAA) medical records, on April 30, 2014, he reported having 278 total flying hours and having flown 60 hours in the 6 months before the examination. The pilot was issued a limited third-class medical certificate dated April 30, 2014. The certificate showed that the pilot must have glasses available for near vision. In spite of repeated efforts, no other pilot records were obtained to substantiate his training and experience beyond what was reported to the FAA. The airplane was a Piper Aircraft Corporation model PA-28-235 Cherokee. The four-place single-engine airplane, serial number 28-10360, was manufactured in 1964 and had an airworthiness certificate classifying its operation in the normal category. The airplane was powered by one Lycoming IO-540-B4B5 carbureted engine rated at 250 horsepower at 2,800 rpm. The facility that maintained the airplane provided all records for maintenance performed on it. According to those records, the airplane underwent an annual inspection on July 5, 2013, at airframe total time 5,425.05 hours. The last maintenance was performed on April 9, 2014, at an airframe total time of 5,533.73 hours. The facility's mechanics replaced the exhaust gas temperature probe in accordance with the manufacturer's instructions and performed a satisfactory operations check. The total airframe time at the accident could not be determined because of the extensive thermal damage to the airplane's tachometer and Hobbs meter. On June 30, 2014 about 0849 mountain daylight time, a Piper PA-28-235, N88