# NTSB LAX97LA103: Cessna 172F, N3757F, San Pablo Bay, CA, February 14, 1997 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: February 13, 1997, 19:30 local (Feb 14, 1997, 03:30 UTC) - Place: San Pablo Bay, CA - Coordinates: 37.979572, -122.329559 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=37.9796&lon=-122.3296&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report October 14, 1997 - Report: Approved by Office Director - NTSB case key (mKey): 29727 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX97LA103 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/29727/pdf - Page: https://openairdocs.org/ntsb/LAX97LA103 ## Probable cause total loss of engine power due to carburetor icing and the pilot's failure to use carburetor heat. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(total) - nonmechanical, cruise - weather condition - carburetor icing conditions - carburetor heat - not used, pilot in command (cause) - Ditching, descent - emergency - light condition - dark night - terrain condition - water ## Analysis A few minutes after takeoff the engine began to run rough and quit, forcing the pilot to ditch. After ditching, the aircraft partially sank in the shallow bay. The pilot sprained his ankle during the water landing and decided to stay with the aircraft. He was located the following morning after manually activating the ELT. The aircraft had last been refueled several weeks before the accident but had not flown until the day of the accident. The pilot estimated there were 28 gallons of fuel remaining. The aircraft logbooks did not reveal any discrepancies. The aircraft was not inspected after the accident. The temperature dew point spread noted in the carburetor icing probability chart is 'moderate icing - cruise power or serious icing - glide power.' ## Factual narrative On February 13, 1997, about 1930 hours Pacific standard time, a Cessna 172F, N3757F, en route to Gnoss Field, Novato, California, lost engine power and ditched in San Pablo Bay, California. The aircraft sustained substantial damage. The pilot, the sole occupant, received minor injuries. The aircraft was operated as a personal flight by the pilot/owner when the accident occurred. The flight originated from the Schellville-Sonoma airport, Sonoma Valley, California, at 1920. Visual meteorological conditions were reported by the pilot and no flight plan was filed. The pilot reported that he had climbed to 1,000 feet msl when the engine began running rough. It began to lose power until the engine finally stopped and he was forced to ditch. After ditching, the aircraft partially sank in about 4 feet of water to the bottom of the bay. The pilot sprained his ankle during the water landing and decided to stay with the aircraft. He climbed on top of the aircraft and stayed there until morning. He was located by a Coast Guard Search and Rescue aircraft after he manually activated the ELT at first light. There was no flotation equipment onboard the aircraft. Rescue personnel reported the aircraft was found less than 0.25 mile from shore, at a position of 38 degrees 5.5 minutes north latitude by 122 degrees 24.7 minutes west longitude. The aircraft was recovered by Parker Diving Service after being in the water for several days. The pilot reported that the aircraft had last been refueled about 3 weeks before the accident, but had not flown until the day of the accident. His report indicates that he flew the aircraft a total of 30 minutes that day. At the time of the accident, the pilot estimated that the aircraft had about 28 gallons of fuel remaining. The aircraft had flown about 170 hours since the engine was overhauled by the owner/mechanic/pilot. The aircraft was equipped with a Brackett Air Filters air induction filter. An FAA Form 337, dated March 21, 1996, was on file for that nonstandard filter. An interview of the pilot and review of the aircraft logbooks by FAA airworthiness inspectors failed to identify any discrepancies. The 1945 weather observation at the Santa Rosa, California, airport, which is 36 miles northwest of the accident site, was reporting a temperature of 55 degrees and a dew point of 32 degrees Fahrenheit. A plot of these points on a carburetor icing probability chart discloses an area of the chart annotated "moderate icing - cruise power or serious icing - glide power." There was no postaccident inspection of the aircraft and the pilot/owner disposed of the wreckage after removing salvageable parts. ## Aircraft - Registration: [N3757F](https://openairdocs.org/deregistered/N3757F-2009-04-09), registration cancelled 2009-04-09, S/N 17255252, built 1966 (OpenAirDocs) - Reported make and model: Cessna 172F - Registry model: [Cessna 172H](https://openairdocs.org/model/cessna-172h) (registry code 2072424) (OpenAirDocs) - Registry engine: [Continental 0-300 series](https://openairdocs.org/engine/continental-0-300-series) (registry code 17022, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 17255252 - Airframe hours: 3060 - Engines: Continental O-300D 145 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Mark Thomas Bidgood - Airworthiness certificate: Standard, Normal - Last inspection: Annual, July 13, 1996, 30 hours before - Departed: 0Q3, SONOMA VALLEY, CA - Destination: O56, NOVATO, CA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 35; flight instructor, airline transport, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 4,125 total, 275 in this make and model, 3,469 as pilot in command, 120 in the last 90 days, 50 in the last 30 days ## Weather - Conditions: Visual (VMC), Night/dark - Wind: 140° at 7 knots - Visibility: 15 statute miles - Lowest ceiling: none - Temperature: 55 °F - Altimeter: 30.00 inHg - Observed at: STS, 36 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 19970213026139A](https://openairdocs.org/incident/19970213026139A), Feb 13, 1997: Cessna 172F, San Pablo Bay, CA, Substantial damage. Lost power ditched in bay near shore. Recovered days later. Unable find cause due salt water. Suspect carb icing. From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.