# NTSB ANC25LA005: Cessna 150, N10495, Lanai City, HI, October 25, 2024 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: October 24, 2024, 15:35 local (Oct 25, 2024, 01:35 UTC) - Place: Lanai City, HI · 4 miles NW of Lanai Airport - Coordinates: 20.8225, -156.93483 - Nearby events: https://openairdocs.org/map.md?lat=20.8225&lon=-156.9348&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-climb to cruise: Fuel related](https://openairdocs.org/ntsb-events/190) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Alaska Regional Office - Parties: FAA, Pacific Electro - SAIBs cited in the narratives: [SAIB CE-09-35](https://openairdocs.org/saib/CE-09-35) (OpenAirDocs) - NTSB case key (mKey): 195377 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC25LA005 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/195377/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=195377 - Page: https://openairdocs.org/ntsb/ANC25LA005 ## Probable cause A partial loss of engine power due to the formation of carburetor ice as a result of the pilot’s improper use of carburetor heat. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Ice/rain protection system: intake anti-ice, deice](https://openairdocs.org/ntsb-findings/01023020): Aircraft › Aircraft systems · Not used/operated (probable cause); cases with it: [Cessna 150L, 1 case](https://openairdocs.org/ntsb-findings/01023020/cases.md?model=2071826), [All aircraft, 108 cases](https://openairdocs.org/ntsb-findings/01023020/cases.md) - [Action: delayed action](https://openairdocs.org/ntsb-findings/02041025): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Cessna 150L, 9 cases](https://openairdocs.org/ntsb-findings/02041025/cases.md?model=2071826), [All aircraft, 894 cases](https://openairdocs.org/ntsb-findings/02041025/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-climb to cruise: Fuel related](https://openairdocs.org/ntsb-events/190) (defining event); cases with it: [Cessna 150L, 6 cases](https://openairdocs.org/ntsb-events/190/sequence.md?model=2071826), [All aircraft, 361 cases](https://openairdocs.org/ntsb-events/190/sequence.md) - [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Cessna 150L, 18 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=2071826), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis The pilot reported that, after climbing to about 800 ft above ground level (agl), the engine suddenly stopped producing power. The pilot reported applying full carburetor heat and partial power was restored. The pilot then removed carburetor heat; again, the engine stopped producing power. The pilot applied full carburetor heat, and the engine regained partial power, but not enough to maintain altitude. The pilot made an emergency landing on a dirt road about three miles north of the airfield. During landing the left wing impacted brush and terrain along the road resulting in substantial damage to the left wing. A postaccident examination of the airframe and engine revealed no preaccident mechanical malfunctions or failures that would have precluded normal operation. Weather conditions at the time of the accident were conducive to carburetor icing at cruise power and serious carburetor icing at glide power. Although the pilot reported that he used the carburetor heat, it is likely that ice had already accumulated to the degree that the carburetor heat was insufficient to melt the ice and restore full engine power. ## Factual narrative On October 24, 2024, about 1535 Hawaii-Aleutian standard time, a Cessna 150 airplane, N10495, sustained substantial damage when it was involved in an accident near Lanai, Hawaii. The pilot and passenger onboard were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that, after climbing to about 800 ft agl, the engine suddenly stopped producing power. The pilot reported applying full carburetor heat and the engine began to make some power. The pilot then reduced carburetor heat and, again, the engine stopped producing power. Subsequently, the pilot applied full carburetor heat, and the engine began to produce some power; however, the engine was not producing enough power to maintain altitude. The pilot made an emergency landing on a dirt road about three miles north of the airfield. The airplane sustained substantial damage to the left wing. The automotive gas (Mogas) was drained from the carburetor bowl; no particulates or water was observed. Continuity was established between the throttle, mixture, and carburetor heat controls in the cockpit and the engine. The spark plug electrodes were inspected and found to have normal wear. The No. 4 cylinder spark plugs were observed to be white in color while the spark plugs from the other cylinders were observed to have a smoky dark gray appearance. Ignition was verified on all spark plugs. Thumb compression was observed on all cylinders. The cylinders were examined with a borescope and the No. 4 cylinder was observed to have light longitudinal scratches from top of ring travel to the bottom of the piston’s stroke. All cylinders were in serviceable condition. The airplane engine was started and idled within normal limits. The rpm was increased to 1,700 and the magnetos and carburetor heat both functioned normally and the engine ran smoothly. The rpm was increased to 2,400 and the engine ran a little rough; rpm was reduced to 2,000 rpm and the engine ran a little worse. The engine idled smoothly when warm at 700 rpm. The oil filter was removed; there were small flakes of metal observed in the oil filter media, but no glitter. The Marvel Schebler MA-3SPA 10-4894-1 carburetor was removed for further inspection. At the time of the accident the carburetor had 708.6 hours since overhaul. The carburetor was reported to be primarily run on unleaded Autogas. On December 5, 2024, the FAA and Marvel Schebler conducted a flow test and disassembled the carburetor. The flow test was slightly rich but within normal parameters. The carburetor was disassembled; a small amount of debris was noted on the internal filter but nothing likely to cause operational issues. On the day of the accident, at 1535, the weather reported at Lanai Airport (LNY), about 3 miles to the south of the accident site, included a temperature of 24°C and a dew point of 19°C. The calculated relative humidity at this temperature and dewpoint was 70%. Review of the icingprobability chart contained within FAA Special Airworthiness Information Bulletin (CE-09-35) – Carburetor Icing Prevention, revealed the atmospheric conditions at the time of the accident were “conducive to serious icing at glide [idle] power.” The bulletin further stated that: …pilots should be aware that carburetor icing doesn't just occur in freezing conditions, it can occur at temperatures well above freezing temperatures when there is visible moisture or high humidity. Icing can occur in the carburetor at temperatures above freezing because vaporization of fuel, combined with the expansion of air as it flows through the carburetor, (Venturi Effect) causes sudden cooling, sometimes by a significant amount within a fraction of a second. Carburetor ice can be detected by a drop in rpm in fixed pitch propeller airplanes and a drop in manifold pressure in constant speed propeller airplanes. In both types, usually there will be a roughness in engine operation. According to FAA Advisory Circular 20-113, "To prevent accident due to induction system icing, the pilot should regularly use [carburetor] heat under conditions known to be conducive to atmospheric icing and be alert at all times for indications of icing in the fuel system." The circular recommended that, when operating in conditions where the relative humidity is greater than 50 percent, "…apply carburetor heat briefly immediately before takeoff, particularly with float type carburetors, to remove any ice which may have been accumulated during taxi and runup." It also stated, "Remain alert for indications of induction system icing during takeoff and climb-out, especially when the relative humidity is above 50 percent, or when visible moisture is present in the atmosphere." According to Transport Canada publication TP 10737 (Use of Automotive Gasoline [Mogas] in Aviation), Mogas is generally higher in volatility than Avgas and will thus absorb more heat from the mixing air when vaporizing, resulting in ice accumulation at higher ambient temperatures. It goes on to say that “the likelihood of carb icing while flying on Mogas is higher,” and advises that: [a]lthough the severity of the carb icing and the methods to deal with it are similar for both Avgas and Mogas, its ONSET is likely to occur at HIGHER AMBIENT TEMPERATURES and LOWER HUMIDITY with Mogas. In other words, conditions under which a pilot may feel there is only a slight risk for carb icing on Avgas may in fact be ideal for the formation of ice while using more volatile Mogas. This will result in the need to select ‘carb heat on’ in less severe icing conditions and for a longer duration while using Mogas. ## Aircraft - Registration: [N10495](https://openairdocs.org/aircraft/N10495), registered now, S/N 15074888, built 1973 (OpenAirDocs) - Reported make and model: CESSNA 150 (L) - Registry model: [Cessna 150L](https://openairdocs.org/model/cessna-150l) (registry code 2071826) (OpenAirDocs) - Registry engine: [Continental 0-200 series](https://openairdocs.org/engine/continental-0-200-series) (registry code 17020, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 15074888 - Year built: 1073 - Airframe hours: 7890.6 - Engines: Continental O-200A 100 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Pacific Electro-Mechanical Inc - Airworthiness certificate: Standard, Utility - Last inspection: Annual, July 12, 2024, 25 hours before - Departed: LNY, Lanai City, HI - Destination: MKK, Kaunakakai, HI - Airport: LNY, Lanai - Equipment: Electronic multifunction display, ADS-B, Electronic flight bag or handheld device ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 47; injuries: none; private; airplane ratings: single-engine land; medical: class 3, without waivers/limitations; last flight review May 18, 2022; seat: left; restraint: 4-point; flight hours: 744.9 total, 662.5 in this make and model, 702.7 as pilot in command, 29 in the last 90 days, 13 in the last 30 days, 2.4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 360° at 10 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 77 °F, dew point 66 °F - Altimeter: 29.97 inHg - Turbulence: Light - Observed at: PHNY, 2 nm away - METAR: PHNY 250103Z AUTO 36010KT 10SM SCT027 SCT032 25/19 A2997 RMK AO2 WSHFT 0043 $ ## 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 20241024017899A](https://openairdocs.org/incident/20241024017899A), Oct 24, 2024: Cessna 150L, Lanai City, HI, Substantial damage. Aircraft departed lny with pilot and passenger for 5th short leg of the day. All previous flights had no issues. During climbout at full power, had sudden loss… ## Docket (6 files) The files NTSB released with the investigation on August 20, 2025, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=195377. 10.5 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 10 pages, 1.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17855171&FileExtension=pdf&FileName=ANC25LA005%206120_Redacted-Rel.pdf - Engine exam (item 2, PDF, 11 pages, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18177218&FileExtension=pdf&FileName=Engine%20Exam-Rel.pdf - Engine inspection notes (FAA) (item 3, PDF, 2 pages, 45 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18452987&FileExtension=pdf&FileName=N10495%20Engine%20Inspection%20Notes%20AJR-Rel.pdf - Maintenance records (item 4, PDF, 18 pages, 5.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17854604&FileExtension=pdf&FileName=Airframe%20and%20engine%20logs%20N10495_Redacted-Rel.pdf - Party representative certification form (item 5, PDF, 10 pages, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17854754&FileExtension=pdf&FileName=Certification%20of%20Party%20Representative%20MJ_Redacted-Rel.pdf - Photos (item 6, PDF, 3 pages, 921 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17854594&FileExtension=pdf&FileName=Investigative%20Photographs%20ANC25LA005-Rel.pdf 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.