Desert Hot Springs, CA, USA
N20556
Cessna 172
On the day of the accident, the pilot departed for a cross-country flight with full fuel and landed at another airport about 24 miles to the west about 80 minutes later. The pilot picked up a passenger there and then took off. About 7 minutes after takeoff, the pilot contacted air traffic control (ATC) to acquire visual flight rules flight- following services at a planned en route altitude of 3,500 ft. The pilot advised that he would "follow the road" as his means of navigation. The airplane continued toward the destination and radar data revealed that for the majority of the flight, the airplane remained at an altitude of 3,500 ft. During this period, the groundspeed varied irregularly, ranging from about 95 to 123 knots. At the east end of a mountain pass, the groundspeed had increased to about 135 knots and remained there until the airplane completed a turn north when the airplane began a steady climb of about 600 fpm. The airplane reached a peak altitude of 4,100 ft, and then began a steady descent of about 1,325 fpm where it appeared to momentarily level off at an altitude of 2,775 ft, and radar contact was lost about 9 seconds later. Just prior to the loss of radar contact, the groundspeed decreased irregularly to about 96 knots, and then increased gradually to about 103 knots by the end of the data. Radar contact was reestablished for a short time with the final radar return recorded at an altitude of about 2,800 ft. and depicted the airplane position as about 1,500 ft southeast of the impact location. The airplane impacted a steep mountain face at an elevation of about 2,500 ft while the pilot was attempting to negotiate a north-south mountain pass with peak terrain elevations of about 2,700 ft. On scene information indicated that the airplane impacted in a wings-level attitude with a significant horizontal speed component. Propeller and engine damage indicated that the engine was developing power at the time of impact. Examination of the airframe and engine did not reveal any pre-impact mechanical deficiencies or failures that would have precluded continued flight. The investigation was unable to determine if the pilot evaluated the weather prior to his departure. Satellite imagery showed higher terrain obscured by clouds, but the pass and accident location were free of cloud cover. However, the region, particularly that near the accident site, was experiencing high winds, generally out of the west, and significant turbulence. Thus, the airplane was on the leeward side of the slopes, where downdraft activity, with potential speeds over 1,000 fpm, would be expected The airplane’s altitude deviations as it navigated the north/south pass were consistent with the airplane encountering significant up- and downdrafts. The pilot’s selected en route altitude of 3,500 ft was too low for the pass that he was transiting, and physically impossible for the route options beyond, regardless of the wind conditions. There were no cloud ceilings or airspace restrictions that would have prevented the pilot from operating at a higher cruise altitude, which would have provided the necessary terrain clearance. For the last 2 minutes of the flight, the airplane exhibited significant altitude excursions, likely as a result of atmospheric disturbances. During the final minute of the flight, the airplane appears to have been affected by a strong downdraft that the pilot either did not recognize or was unable to counter. The most significant flawed decision was the pilot's selection of the incorrect low en route altitude, which suggested either lack of or inadequate preflight planning. The pilot's improper low altitude choice, combined with the high terrain, strong winds, downdrafts, and limited climb capability of the airplane left little or no margin for ensuring terrain clearance and safe transit through the pass.
HISTORY OF FLIGHTOn February 5, 2019, about 1815 pacific standard time, a Cessna 172M airplane, N20556, was destroyed when it was involved in an accident near Desert Hot Springs, California. The pilot and passenger received fatal injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot departed from Corona Municipal Airport (AJO), Corona, California about 1530 and landed at San Gabriel Valley Airport (EMT), El Monte, California, about 1 hour 20 minutes later to pick up a passenger. A witness at EMT observed the accident airplane parked and tied down on the ramp adjacent to his airplane about 1710. The witness observed the accident pilot perform a preflight inspection that he described as “rushed and cursory.” The accident pilot and a passenger then boarded the accident airplane. The witness noticed that the left wing tiedown line was still attached to the accident airplane when the pilot began to start the engine. The witness got the pilot's attention, made him aware of the tiedown problem, and then by mutual agreement, the witness disconnected the tiedown from the accident airplane. The pilot then taxied to and departed from runway 19 a few minutes later. The flight departed about 1740, and about 7 minutes later, the pilot contacted air traffic control for visual flight rules (VFR) flight-following services to North Las Vegas Airport (VGT), Las Vegas, Nevada, with a planned en route altitude of 3,500 ft. The request was granted, and the pilot was provided with a discrete transponder code for the flight. The pilot advised that he would "follow the road" as his means of navigation. About 16 minutes after initial contact, radar services were terminated because of radar coverage limitations. The pilot was instructed to return to the standard VFR transponder code of 1200, and to re-contact air traffic control once he was east of the Banning Municipal Airport (BNG), Banning, California. The data indicated that after takeoff from EMT, the airplane climbed to an altitude of 3,500 ft, and maintained that as its cruise altitude until about 1814. During that period, the groundspeed varied irregularly, ranging from about 95 to 123 knots. When radar coverage resumed at the east end of the Banning Pass, the groundspeed had increased to about 135 knots and remained there until about 1813. About 1814, after the airplane had completed its turn north and was about 9 miles north of Palm Springs airport (PSP), Palm Springs, California, the airplane began a steady climb of about 600 fpm. The airplane reached a peak altitude of 4,100 ft at 1815:03, and then began a steady descent of about 1,325 fpm until 1816:12, where it appeared to momentarily level off at an altitude of 2,775 ft, and radar contact was lost about 9 seconds later. Between 1813 and 1815:12, the groundspeed decreased irregularly to about 96 knots, and then increased gradually to about 103 knots by the end of the data. The final radar return was recorded at 1816:21 with an altitude of about 2,800 ft., and depicted the airplane position as about 1,500 ft southeast of the impact location. Shortly thereafter, the controller advised the pilot that radar contact had been lost; the pilot did not respond despite multiple subsequent controller attempts. The FAA issued an alert notice for the missing airplane at 1843. The wreckage was located about 2120. PERSONNEL INFORMATIONRepresentatives of the operator, Flight Academy Los Angeles (FALA), from which the pilot rented the airplane, reported that the pilot had come to FALA in January 2019 "to build [flight] time." FALA records indicated that the pilot accrued 31 flight hours on FALA airplanes in January and February 2019. All of that time was in Cessna 172 airplanes and included a 1.4-hour checkout by an instructor. As a result of this checkout, FALA approved the pilot only for VFR day flights. Because the instructor knew that the pilot had received all of his flight training in Florida, he "focused heavily on how to navigate and fly around the Southern California area," including discussions of potential wind issues in the Banning Pass. METEOROLOGICAL INFORMATIONGeneral A search of Aviation Flight Service Station Leidos indicated that the pilot had not contacted them for any weather briefings, flight plans, or other services for the flight. It is unknown what the pilot used in familiarizing himself with the en route weather conditions before departure. VFR conditions prevailed generally between EMT and VGT, but high winds and turbulence were predominant in the existing and forecast conditions. A search of Remote Automatic Weather Stations (RAWS) operated by the U.S. Forest Service and the Bureau of Land Management provided 4 stations reporting nearby wind information. The Cabazon and Whitewater RAWS stations were respectively located near the west and east entrances of the Banning Pass. The Yucca Valley station was 10 miles northeast of the accident location, and the Burns Canyon station was 10 miles north of the accident location. According to the local National Weather Service Weather Forecast Office meteorologist “the winds at the Whitewater RAWS were gusting from 45 to 60 mph during the period of the accident. The flight would have traversed Banning Pass/San Gorgonio Pass which funnels strong winds. This is a peak area for winds and the Whitewater RAWS site would have been very representative of those winds in the vicinity of the accident site”. Data from the Burns Canyon RAWS site (10 miles north of the accident site), at the time of the accident, were from the west-southwest at 35 mph gusting to 56 mph with a maximum of 69 mph within the hour after the accident. Sun and Moon Lighting Sunset near the accident location occurred at 1720, and civil twilight ended at 1746. The moon phase was a waxing crescent with 1% of the moon's visible disk illuminated. At the time of the accident, the moon was just setting. WRECKAGE AND IMPACT INFORMATIONThe airplane came to rest on a steep unstable hillside, about 800 ft west of and about 399 ft above a road. The wreckage was at an elevation of about 2,500 ft and about 1,500 ft beyond the last radar return. The wreckage was highly compressed, and only a few components had completely separated from the airplane. The road was near the bottom of a winding valley that forms a pass through a small mountain range that separates a low, flat desert region from more rugged desert terrain that has base elevations about 1,500 ft higher than the low desert. Maximum elevations of peaks near the road and pass range up to 2,700 ft. The low desert, the pass, and the upper desert are all sparsely populated, and very sparsely illuminated. The lower cowl and the navigation light lens fragments were found at what appeared to be the impact point, about 30 ft above where the main wreckage came to rest. The observed ground scars (disturbed soil & rocks) were consistent with the airplane falling/sliding down to its final resting location. The relative locations of the left and right lens fragments were consistent with the airplane being right side up when it struck the mountain face. The forward section of the airplane was upright, and partially covered with soil/rocks that had slid downhill. The fuselage was severely crushed and torn, and the wings and empennage were severely torn and deformed. The approximate orientation of the wreckage was on a heading of 230°. The mountain impact face and wreckage distribution were consistent with this also being the approximate ground track at the time of impact. There was no indication of fire. First responders reported that the airplane was "covered in fuel" when they arrived at the wreckage; that fuel had disappeared by the time the wreckage was examined by investigators. The all metal fixed pitch two blade propeller was fracture-separated from the engine at its attach flange. All flight controls were present and attached to their respective aerodynamic surfaces. Control cable continuity was established for the ailerons, elevators, pitch trim, and rudder. The pitch trim actuator was found in a position corresponding to 5° trailing edge up. The flaps and their actuator were in the fully retracted position. The emergency locator transmitter was found fractured and separated from its mount but remained attached to its external antenna. The fuel selector valve was set to the right tank. The B-nut attached to the "VAC" port on the attitude indicator was hand tight. The attitude indicator was disassembled; its gyro rotor was found offset inside the rotor housing, free to rotate, but exhibited no rotational scoring. Lack of postimpact rotor or housing rotational scoring is sometimes indicative of lack of gyro operation at the time of the accident. The engine had sustained significant impact damage; the propeller, magnetos, starter, alternator, and portions of the carburetor and intake and exhaust systems had been fracture-separated from their respective mountings. Magneto-to-engine timing could not be determined. The left magneto produced sparks when manually rotated, but the right magneto was too damaged to test. The spark plug electrodes were mechanically undamaged, and the electrodes displayed coloration consistent with normal operation. The rear-mounted vacuum pump remained attached to the mounting pad. Three of the four hold down nuts for the vacuum pump were present and secure, but one was absent. There was no evidence that the nut had been removed by impact. The frangible drive shaft was intact, but one vane was fractured, and the rotor was fractured into multiple pieces The airplane was not equipped with an engine driven fuel pump. The carburetor fracture surface signatures were consistent with overload. The float assembly and needle valve were destroyed. The throttle control rod end was found securely attached at the control arm of the carburetor, but the mixture arm had been pulled from the carburetor due to overload. Both the throttle and mixture controls had been moved beyond the normal operating range during the accident, and reliable setting positions at the time of impact could not be determined. Examination of the engine revealed no evidence of pre-impact anomalies or malfunctions that would have prevented normal operation. ADDITIONAL INFORMATIONReview of sectional aeronautical charts that encompassed the region between EMT and VGT revealed that north of the pass in which the accident occurred, the terrain elevations increased significantly, and generally were above 3,500 ft. Each quadrant on the chart contained a Maximum Elevation Figure (MEF), which represented the highest elevation within the quadrant, including terrain and other obstacles (towers, trees, etc.). The minimum MEF value for the area north of the pass was 50 (5,000 ft), and the maximum value was 123 (12,300 ft). Turbulence The FAA publication "Pilot's Handbook of Aeronautical Knowledge" stated that the intensity of the turbulence associated with ground obstructions depends on the size of the obstacle and the primary velocity of the wind. This condition is even more noticeable when flying in mountainous regions. While the wind flows smoothly up the windward side of the mountain and the upward currents help to carry an aircraft over the peak of the mountain, the wind on the leeward side does not act in a similar manner. As the air flows down the leeward side of the mountain, the air follows the contour of the terrain and becomes increasingly turbulent. This tends to push an aircraft into the side of a mountain. The stronger the wind, the greater the downdrafts and turbulence. Due to the effect terrain has on the wind in valleys or canyons, downdrafts can be severe. The handbook cautioned that "a prudent pilot is well advised to seek out a mountain qualified flight instructor and get a mountain checkout before conducting a flight in or near mountainous terrain." FLIGHT RECORDERSA Garmin Aera 660 was recovered from the wreckage and sent to the NTSB Vehicle Recorders Laboratory for potential data download. However, the most recent data file was dated December 19, 2018; no accident flight data were recovered from the device. MEDICAL AND PATHOLOGICAL INFORMATIONThe Riverside County Sheriff's Department conducted an autopsy on the pilot. The cause of death was determined to be multiple blunt force injuries. The FAA Bioaeronautical Research Sciences Laboratory, Oklahoma City, Oklahoma, conducted forensic toxicology examinations on specimens from the pilot, and reported that no carbon monoxide, ethanol, or any screened drugs were detected. AIDS TO NAVIGATIONThe investigation was unable to determine the pilot's intended route of flight, or what, aside from "the road," the pilot was using for navigation references. No aeronautical charts were recovered from the accident site or wreckage. Radar ground tracks of the flight did not overlie any published Victor Airways. The pilot communicated to air traffic control (ATC) that the airplane equipment suffix was "golf" (indicating GPS equipped), but the panel-mounted GPS device in the airplane did not record the accident flight. This prevented conclusive determination of whether the device was operating at the time, because it can be used for navigation without capturing the flight in its memory. Radar ground track depicted the airplane maneuvering around and between two closely-spaced Class C airspaces (Ontario and Riverside March Field); such navigation would be very difficult without a GPS for guidance.
The pilot's inadequate and/or improper preparation for the flight in which he selected an altitude too low to assure terrain clearance and resulted in an impact with terrain in turbulent downdraft conditions.
Source: NTSB Aviation Accident Database
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