# NTSB ANC24LA011: Cessna 172P, N53725, Kahului, HI, December 23, 2023

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Class 3 · Limited · Final report
- Date: December 23, 2023, 10:00 local (20:00 UTC)
- Place: Kahului, HI
- Coordinates: 20.893719, -156.45548
- Nearby events: https://openairdocs.org/map.md?lat=20.8937&lon=-156.4555&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Defining event: [Approach-VFR pattern base: Fuel related](https://openairdocs.org/ntsb-events/190)
- Highest injury: No injuries
- Injuries: 3 uninjured
- Status: Completed
- Report: Approved by Office Director
- Investigation class: Class 3
- NTSB office: Alaska Regional Office
- Parties: FAA Honolulu FSDO
- SAIBs cited in the narratives: [SAIB CE-09-35](https://openairdocs.org/saib/CE-09-35) (OpenAirDocs)
- NTSB case key (mKey): 193608
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC24LA011
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/193608/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=193608
- Page: https://openairdocs.org/ntsb/ANC24LA011

## Probable cause

A partial loss of engine power due to the formation of carburetor ice, which resulted in the inability to maintain altitude in the traffic pattern. Contributing to the outcome was the pilot’s delayed use of carburetor heat in conditions conducive to the formation of carburetor ice.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Use of equip/info: use of checklist](https://openairdocs.org/ntsb-findings/02063030): Personnel issues › Task performance · Pilot; cases with it: [Cessna 172P, 3 cases](https://openairdocs.org/ntsb-findings/02063030/cases.md?model=2072436), [All aircraft, 336 cases](https://openairdocs.org/ntsb-findings/02063030/cases.md)
- [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 172P, 2 cases](https://openairdocs.org/ntsb-findings/01023020/cases.md?model=2072436), [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 172P, 9 cases](https://openairdocs.org/ntsb-findings/02041025/cases.md?model=2072436), [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.

- [Approach-VFR pattern base: Fuel related](https://openairdocs.org/ntsb-events/190) (defining event); cases with it: [Cessna 172P, 4 cases](https://openairdocs.org/ntsb-events/190/sequence.md?model=2072436), [All aircraft, 361 cases](https://openairdocs.org/ntsb-events/190/sequence.md)
- [Emergency descent: Landing area undershoot](https://openairdocs.org/ntsb-events/370); cases with it: [Cessna 172P, 2 cases](https://openairdocs.org/ntsb-events/370/sequence.md?model=2072436), [All aircraft, 201 cases](https://openairdocs.org/ntsb-events/370/sequence.md)

## Analysis

The pilot reported that, after five touch-and-go landings, while on the base leg of the traffic pattern, the engine lost partial power. The pilot applied carburetor heat, switched the fuel tanks, and pumped the throttle, but engine power remained at idle. The pilot was unable to reach the runway and performed a forced landing short of the runway. Upon touchdown, the airplane nosed over and came to rest inverted, which resulted in substantial damage to the fuselage and empennage. The atmospheric conditions at the time of the accident were conducive to serious icing at glide power. Although the pilot reported that he used carburetor heat after experiencing the loss of engine power, it is likely that the ice had already accumulated to the degree that the carburetor heat was insufficient to melt the ice and restore full engine power. Based on the available information, it is likely that the partial loss of engine power was a result of the formation of carburetor ice. A postaccident examination of the engine revealed no preimpact mechanical malfunctions or failures that would have precluded normal operation.

## Factual narrative

On December 23, 2023, about 1000 Hawaii-Aleutian standard time, a Cessna 172P, N53725, was substantially damaged when it was involved in an accident near Kahului Airport (PHOG), Kahului, Hawaii. The pilot and two passengers were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that, after five touch-and-go landings, while on the base leg of the traffic pattern, the engine lost partial power. The pilot applied carburetor heat, switched the fuel tanks, and pumped the throttle, but engine power remained at idle. Unable to reach the runway, the pilot performed a forced landing short of the runway. Upon touchdown, the airplane nosed over and came to rest inverted, which resulted in substantial damage to the fuselage and empennage. About 20 gallons of automotive fuel remained in the fuel tanks at the accident site. A postaccident engine examination revealed the presence of fuel in the strainer and carburetor bowl. The fuel was drained from the strainer and carburetor bowl, and a trace amount of water was found. Continuity was established on all linkages to the carburetor and airbox; all linkages functioned normally, and the butterfly valves were found to operate normally. The spark plugs were removed and the plug electrodes appeared normal. The magnetos produced spark on all ignition leads. The airplane was started normally and accelerated smoothly from idle to 1,700 rpm with no anomalies noted. A review of the local meteorological data and the Carburetor Icing Probability Chart located in the Federal Aviation Administration’s (FAA) Special Airworthiness Information Bulletin CE-09-35, Carburetor Icing Prevention, dated June 30, 2009, revealed that the weather conditions at the time of the accident were conducive to serious icing at glide power. FAA Special Airworthiness Information Bulletin (CE-09-35) – Carburetor Icing Prevention, 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 Transport Canada 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 ishigher,” 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 at 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: [N53725](https://openairdocs.org/aircraft/N53725), registered now, S/N 17274808, built 1981 (OpenAirDocs)
- Reported make and model: CESSNA 172P
- Registry model: [Cessna 172P](https://openairdocs.org/model/cessna-172p) (registry code 2072436) (OpenAirDocs)
- Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 17274808
- Year built: 1981
- Airframe hours: 6858
- Engines: Lycoming O320-D2J 160 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, January 23, 2023, 134.8 hours before
- Departed: PHOG, Kahului, HI
- Destination: Same as departure
- Airport: PHOG, Kahului Airport
- Equipment: Stall warning system, ADS-B, Auto-pilot

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 64; injuries: none; private; airplane ratings: single-engine land; medical: class 3, unknown; last flight review December 14, 2023; seat: left; restraint: 4-point; flight hours: 20,000 total, 2,200 in this make and model, 120 in the last 90 days, 30 in the last 30 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: 50° at 19 knots, gusting 25
- Visibility: 9 statute miles
- Temperature: 77 °F, dew point 66 °F
- Altimeter: 30.13 inHg
- Observed at: HOG, 1 nm away
- METAR: PHOG 231954Z 05019G25KT 10SM FEW020 25/19 A3013 RMK AO2 PK WND 05027/1938 SLP207 T02500194

## 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 20231223022269A](https://openairdocs.org/incident/20231223022269A), Dec 23, 2023: Cessna 172P, Kahalui, HI, Substantial damage. Pilot was performing touch and goes at Kahului Airport. During sixth approach, aircraft lost engine power at approximately 500 feet and 1 mile from the runway.…

## Docket (5 files)

The files NTSB released with the investigation on April 2, 2025, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=193608. 18.4 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 2.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16810047&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf
- FAA inspector's statement (item 2, PDF, 1 page, 91 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16967354&FileExtension=pdf&FileName=MOR%20Mike%20Marzke%20and%20Spencer%20Leonard_MH-Rel.pdf
- Carburetor icing probability graph (item 3, PDF, 1 page, 526 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16968220&FileExtension=pdf&FileName=ANC24LA011%20Carburetor%20Icing%20Probability%20Graph-Rel.pdf
- Maintenance records (item 4, PDF, 8 pages, 15.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16969208&FileExtension=pdf&FileName=2-Rel.pdf
- Photos (item 5, PDF, 3 pages, 662 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18490326&FileExtension=pdf&FileName=Photos-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.

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