Bolinas, CA, USA
N737QQ
CESSNA 172N
During a personal cross-country flight, the non-instrument-rated private pilot reported to air traffic control that the airplane would be descending below the marine layer clouds to fly along the coastline to the intended destination. Before the pilot's descent, he asked the controller about the cloud base altitude, but the controller did not have that information. The pilot stated that he would descend to 1,500 ft. The controller asked the pilot if he was going to follow the shoreline, and the pilot replied, "yes, at 2,100 [ft]." Shortly afterward, the controller advised the pilot to contact the next sector. About 13 minutes later, the pilot attempted to contact the next sector, but that sector controller was not able to understand the transmission. The controller instructed the pilot to contact approach control in 15 miles. No further communications from the pilot were received. The wreckage evidence indicated that the airplane impacted rising terrain. Witnesses in the area did not see the accident airplane but heard a loud noise about the time of the accident. The witnesses reported a thick fog layer near the accident site. The airframe and engine examinations found no mechanical anomalies that would have precluded normal operation. The accident site was in an area that had a low- to mid-level pressure troughs, which induced an onshore flow toward the mountainous terrain along the coastline. The persistent onshore flow was favorable for the development of a marine layer and mountain obscuration. An AIRMET that was valid for the time of the accident indicated mountain obscuration and instrument flight rules (IFR) conditions along the coastal water; the accident site was less than 1-mile northeast of the coastline. The closest official weather observation site to the accident site, which was located 15 miles northeast of the accident site, reported an overcast ceiling at 2,600 above ground level (agl). An unofficial weather site that was 5 miles east-northeast of the accident site reported a temperature and dew point that were nearly equal and a relative humidity above 85%. These conditions increased the potential for instrument meteorological conditions (IMC) in the area. In addition, the cloud ceilings near the accident site were likely at 800 ft mean sea level according to the upper air sounding data. A review of archived ForeFlight data and DUATS and Leidos records revealed that the pilot received several weather briefings in preparation for the flight, and that the briefings identified marginal VFR and IMC conditions along the intended route of flight. Thus, the pilot had sufficient weather forecast information to understand that IFR and mountain obscuration conditions would have existed northward along the coastline.
HISTORY OF FLIGHTOn September 7, 2017, about 1400 Pacific daylight time, a Cessna 172N airplane, N737QQ, impacted trees in Point Reyes National Park, Bolinas, California. The private pilot was fatally injured, and the airplane was substantially damaged. The airplane was owned by Sunwest Aviation Inc. and was operated by the pilot as a Title 14 Code of Federal Regulations Part 91 personal flight. Marginal visual meteorological conditions prevailed at the time of the accident, and a visual flight rules (VFR) flight plan had been filed. The flight originated from the Santa Ynez Airport (IZA), Santa Ynez, California, about 1130 and was destined for the Charles M. Schulz-Sonoma County Airport (STS), Santa Rosa, California. According to the Federal Aviation Administration (FAA), at 1249, when the airplane was at an altitude of 6,500 ft mean sea level (msl), the pilot established radio communications with Northern California Terminal Radar Approach Control (NCT), Seca sector, and informed the controller that he was en route to STS. At 1311, the controller assigned the pilot an altitude of 6,000 ft msl. Six minutes later, the pilot indicated that he would be descending below the marine layer. When the controller queried the pilot about the intended altitude, the pilot asked about the altitude of the cloud bases. The controller did not know the cloud base altitude, and the pilot replied that the airplane would be descending to 1,500 ft msl. At 1321, the controller asked the pilot if he would be following the shoreline, and the pilot responded, "yes at 2,100 [ft]." At 1325, the controller terminated flight following services by the Seca sector, and advised the pilot that the next sector controller would not be able to see the airplane at its current altitude, radar service was terminated, squawk VFR (1200 code) and frequency change was approved. The controller advised the pilot that he could attempt communication with the NCT Boulder sector on a frequency of 133.95 MHz. About 13 minutes later, the Boulder sector received an unintelligible transmission, and the controller informed the pilot that he could not be heard at the airplane's altitude along the coastline; and to try the NCT Approach controller in 15 miles on a frequency of 135.1 MHz. No further communication from the pilot was received. Two Point Reyes National Park employees, located in a different area of the park, heard a loud noise at the time of the accident but did not know the source of the sound. Both employees reported that dense fog was present at the time of the accident. The flight was the subject of an alert notification, that was issued by Oakland Air Route Traffic Control Center after radar contact with the airplane was lost. The airplane was equipped with an ACK Technologies Inc. E-04 emergency locator transmitter (ELT) 406 MHz; it activated during the accident sequence, and the signal was used to locate the airplane at the accident site. The wreckage was found on the day after the accident at 1300. The accident site was 35 miles south-southeast of STS. PERSONNEL INFORMATIONThe pilot held a private pilot certificate with a rating for airplane single-engine land. He did not have an instrument rating. At the time of his most recent FAA medical application, dated October 20, 2016, the pilot reported 104 hours of total flight experience with no hours logged in the previous 6 months. The pilot also held a third-class medical certificate with the limitation that he must wear corrective lenses. AIRCRAFT INFORMATIONAccording to the airframe logbook, a 50-hour inspection had been performed on March 10, 2017, and the airplane was determined to be in airworthy condition. At that time, the airplane had accumulated a total time of 4,187.37 hours and 2,100.9 hours of tachometer time. METEOROLOGICAL INFORMATIONThe closest official weather observation site to the accident was Gnoss Field Airport, Novato, California, which was 15 miles northeast of the accident site. The reported weather at 1355 was wind from 240° at 7 knots, 10 miles visibility, overcast ceiling at 2,600 ft above ground level (agl), temperature 21°C, dew point 16°C, and an altimeter setting of 29.99 inches of mercury. The closest non-official surface observation to the accident site, WOODACRE a remote automatic weather station, was located 5 miles east-northeast of the accident site. The reported weather at 1351 was wind from 240° at 4 mph with gusts to 12 mph, temperature 16°C, dew point 15.9°C, and a relative humidity of 99 percent. The reported weather at 1451 was wind from 232° at 4 mph with gusts to 8 mph, temperature 16°C, dew point 15.6°C, and a relative humidity of 98 percent. The next closest remote automatic weather station to the accident site, BARNABY was located 6 miles north-northeast of the accident site. The reported weather at 1311 was wind from 200° at 2 mph with gusts to 7 mph, temperature 17.7°C, dew point 16.4°C, and a relative humidity of 92 percent. The reported weather at 1422 was wind from 180° at 2 mph with gusts to 7 mph, temperature 18.3°C, dew point 16.2°C, and a relative humidity of 88 percent. The surface analysis chart at 1400 the day of the accident, showed a surface trough located east of the accident site stretching northwest to southeast from north-central California, southward to Bakersfield, California. The station models around the accident site depicted cloudy skies. The Upper Air Charts identified a mid-level trough existed above the accident site with an onshore wind. Troughs can act as lifting mechanisms to aid in the production of clouds and precipitation if enough moisture is present. A High-Resolution Rapid Refresh model sounding was plotted for the accident site at the time of the accident (1400). The sounding depicted the lifted condensation level at 831 ft msl, a convective level at 1,979 ft and a level of free convection at 831 ft. A sounding analysis program identified that clouds were likely between 831 ft and 4,500 ft msl at 1400. Visible and infrared data from the Geostationary Operational Environmental Satellite Number 15 (GOES-15), showed cloud cover over the accident site that was moving from the southwest to the northeast. The GOES-15 data along with the sounding data indicated that the cloud-top heights over the accident site were 10,000 ft. AIRMET Sierra, which was valid for the accident site at the accident time warned of mountain obscuration conditions in clouds, precipitation, and mist. An Area Forecast (AF) issued at 1245, which was valid at the time of the accident forecasted broken clouds at 1,500 ft msl with cloud tops at 3,000 ft. The AF expected at 1400 scattered clouds at 1,500 ft with an additional scattered cloud layer at 14,000 ft. The AF issued at 0645 expected, by 1300 overcast clouds at 1,500 ft with occasional visibility of 5 miles in mist. The accident pilot received a weather briefing for the accident flight route from Leidos the night before the accident. The pilot also received 3 additional weather briefings the day of the accident. He filed a flight plan with ForeFlight on the day of the accident. The ForeFlight weather briefing included the latest METARs, AF, AIRMETs, PIREPs, TAFs, and winds aloft forecast, which were valid for the proposed route of flight. In addition, the pilot received an official Direct User Access Terminal Service (DUATS) weather briefing at 1102 on the day of the accident. The DUATS briefing also included the latest METARs, TAFs, AF, AIRMETs, and winds aloft forecast, which were valid along the proposed route of flight. AIRPORT INFORMATIONAccording to the airframe logbook, a 50-hour inspection had been performed on March 10, 2017, and the airplane was determined to be in airworthy condition. At that time, the airplane had accumulated a total time of 4,187.37 hours and 2,100.9 hours of tachometer time. WRECKAGE AND IMPACT INFORMATIONThe wreckage was located less than 1-mile northeast of the Pacific Ocean coastline in a densely forested area at an elevation of 646 ft. The left wing separated at the wing root and was found suspended from a 60-ft tree. The airplane came to rest inverted about 50 ft from the left wing. The outboard left aileron was found near the fuselage. The right wing along with the right flap separated from the airplane and was suspended from a tree. Flight control continuity was established at the accident site. The aileron interconnect cables remained continuous. The left yoke chain remained engaged at the sprocket in the cockpit. The right yoke sustained impact damage and was fractured; the chain was loose in the sprocket. The control column sustained impact damage near the pedestal assembly. The elevator cables were continuous from the forward to aft bell-cranks. The rudder cables remained attached and continuous to the rudder horn; the torque tubes for the rudder assembly sustained impact damage. The elevator trim cables sustained impact damage; the chain was broken and separated from the front sprocket, and the cables were continuous to the aft chain. The engine and the upper portion of the instrument panel separated from the airplane and came to rest about 50 ft beyond the main wreckage. The magnetos, vacuum pump, cylinders, and oil sump remained attached to the engine at their normal positions. The oil sump had a puncture on the right side. No other obvious holes were observed in the engine case. The engine starter ring gear separated from the engine. The propeller assembly separated from the engine. A fuel receipt from the day of the accident was found in the main wreckage; the airplane had been refueled with 14.6 gallons of 100 low-lead fuel. The carburetor was open with no residual fuel observed in the bowl; however, the side walls of the brass floats had compressed inward, consistent with hydraulic deformation at the time of impact. An engine examination was performed at Air Transport, Phoenix, Arizona. After a visual examination of the engine, the top spark plugs were removed; according to the Champion Aerospace check-A-Plug chart (AV-27), the electrodes exhibited a "worn out-normal" appearance. Rotational continuity was established through the engine and valve train via manual rotation of the drive shaft. Thumb compression was obtained in all cylinders in proper firing order. Equal movement of the intake and exhaust rocker arms was observed. The internal components of the engine were examined with a borescope and found to be unremarkable with no foreign debris present. The fuel inlet finger screen was free of debris. The oil filter was opened, and the filter element was found to be free of foreign debris. The vacuum pump was disassembled; the vanes and internal components were intact and unremarkable. Both magnetos remained secured at their respective mounting pads on the engine. The left magneto was manually rotated and produced spark at all posts. The right magneto was also manually rotated and produced intermittent spark at all posts. The right magneto had impact damage to its case and was disassembled; no internal discrepancies were noted. Both magnetos were sent to Champion Aerospace, Liberty, South Carolina, for further examination. The magnetos were inspected and then placed on a testing unit for a functionality test. Both magnetos ran continuously for several minutes. After the functional check, the right magneto was again opened for further examination; the internal body of the magneto was free of debris, and the internal parts were in good condition with minimal normal wear marks. The examination and functional test found that both magnetos were within acceptable manufacturer operating limitations with no intermittent output. MEDICAL AND PATHOLOGICAL INFORMATIONThe Marin County Sheriff's Office, Coroner Division, San Rafael, California, performed an autopsy of the pilot. His cause of death was multiple blunt impact injuries. Toxicology testing performed at the FAA Forensic Sciences Laboratory found no carbon monoxide, ethanol, and no test-for drugs in the pilot's specimens. Cyanide testing was not performed.
The non-instrument rated private pilot's improper decision to embark on a flight and continue to fly into forecasted instrument meteorological conditions and mountain obscuration while conducting a visual flight rules flight.
Source: NTSB Aviation Accident Database
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