# NTSB ERA24LA178: Cessna 172, N8337X, Manassas, VA, April 15, 2024

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Class 3 · Limited · Final report
- Date: April 14, 2024, 20:08 local (Apr 15, 2024, 00:08 UTC)
- Place: Manassas, VA
- Coordinates: 38.726086, -77.521236
- Nearby events: https://openairdocs.org/map.md?lat=38.7261&lon=-77.5212&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Defining event: [Enroute-descent: Fuel related](https://openairdocs.org/ntsb-events/190)
- Highest injury: Minor injuries
- Injuries: 1 minor, 1 uninjured
- Status: Completed
- Report: Approved by Office Director
- Investigation class: Class 3
- NTSB office: Eastern Region Aviation
- Parties: FAA/FSDO
- SAIBs cited in the narratives: [SAIB CE-09-35](https://openairdocs.org/saib/CE-09-35) (OpenAirDocs)
- NTSB case key (mKey): 194084
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA24LA178
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/194084/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=194084
- Page: https://openairdocs.org/ntsb/ERA24LA178

## Probable cause

The pilot’s failure to apply carburetor heat before reducing engine power during a prolonged descent while operating in environmental conditions conducive to the development of carburetor ice, which resulted in a total loss of engine power due to carburetor icing.

## 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 172C, 1 case](https://openairdocs.org/ntsb-findings/01023020/cases.md?model=2072408), [All aircraft, 108 cases](https://openairdocs.org/ntsb-findings/01023020/cases.md)
- [Action: lack of action](https://openairdocs.org/ntsb-findings/02041030): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Cessna 172C, 1 case](https://openairdocs.org/ntsb-findings/02041030/cases.md?model=2072408), [All aircraft, 792 cases](https://openairdocs.org/ntsb-findings/02041030/cases.md)
- [Info processing/decision: identification/recognition](https://openairdocs.org/ntsb-findings/02041510): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Cessna 172C, 1 case](https://openairdocs.org/ntsb-findings/02041510/cases.md?model=2072408), [All aircraft, 559 cases](https://openairdocs.org/ntsb-findings/02041510/cases.md)
- [Temp/humidity/pressure: conducive to carburetor icing](https://openairdocs.org/ntsb-findings/03031030): Environmental issues › Conditions/weather/phenomena · Response/compensation (probable cause); cases with it: [Cessna 172C, 1 case](https://openairdocs.org/ntsb-findings/03031030/cases.md?model=2072408), [All aircraft, 435 cases](https://openairdocs.org/ntsb-findings/03031030/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Enroute-descent: Fuel related](https://openairdocs.org/ntsb-events/190) (defining event); cases with it: [Cessna 172C, 1 case](https://openairdocs.org/ntsb-events/190/sequence.md?model=2072408), [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 172C, 1 case](https://openairdocs.org/ntsb-events/370/sequence.md?model=2072408), [All aircraft, 201 cases](https://openairdocs.org/ntsb-events/370/sequence.md)
- [Landing-landing roll: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Cessna 172C, 10 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=2072408), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md)
- [Landing-landing roll: Nose over/nose down](https://openairdocs.org/ntsb-events/096); cases with it: [Cessna 172C, 5 cases](https://openairdocs.org/ntsb-events/096/sequence.md?model=2072408), [All aircraft, 2,287 cases](https://openairdocs.org/ntsb-events/096/sequence.md)

## Analysis

The pilot reported that the airplane was in cruise flight at 5,500 ft mean sea level (msl) before he reduced engine power to comply with air traffic control descent instructions. The pilot did not apply carburetor heat at any time during the descent from 5,500 ft to 2,000 ft. At 2,000 ft msl, with the destination airport in sight, he applied throttle, but the engine did not respond. The pilot informed the tower controller that the “motor was unresponsive” and was cleared to land. The airplane touched down in a grassy area on airport property short of the runway, collided with a drainage culvert, and nosed over, resulting in substantial damage to the vertical stabilizer and the right-wing lift strut. Although low compression was noted in two cylinders during the postaccident engine examination, that condition was attributed to leakage past the intake valves and likely would not have resulted in the total loss of engine power reported by the pilot. Review of weather information indicated that the airplane was operating in an area conducive to the development of serious carburetor ice at glide or idle engine power settings. It is likely that the carburetor accumulated ice during the prolonged descent without the use of carburetor heat, which resulted in the total loss of engine power.

## Factual narrative

On April 14, 2024, about 2008 eastern daylight time, a Cessna 172C, N8337X, was substantially damaged when it was involved in an accident near Manassas, Virginia. The private pilot was not injured, while the passenger sustained minor injury. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot was enroute to the destination airport at 5,500 ft mean sea level (msl). According to communications information from Federal Aviation Administration (FAA), the pilot was instructed by air traffic control to descend to, but remain at or above, 2,600 ft msl, and the pilot reported that he reduced throttle, but did not apply carburetor heat at any time during the descent. According to ADS-B data, the airplane began gradually descending from about 5,500 ft after 1959:09. The pilot was later cleared to descend to 2,000 ft msl, and while flying at that altitude with the destination airport in sight, he applied throttle to increase engine power, but the engine did not respond. About 2006, he informed the tower controller that the “motor was unresponsive” and the controller cleared the airplane to land on runway 16R. The airplane touched down in a grassy area on airport property short of the runway, collided with a drainage culvert, and nosed over, resulting in substantial damage to the vertical stabilizer. Posataccident examination of the engine by a FAA inspector confirmed crankshaft, camshaft, and valvetrain continuity. Thumb suction and compression were noted in all cylinders, though it was low in two of the cylinders due to leakage past each intake valve. Examination of the air induction, ignition, exhaust, and fuel metering systems revealed no evidence of preimpact failure or malfunction. Impact damage to the carburetor precluded functional testing of the engine. A High Resolution Rapid Refresh (HRRR) model sounding was created for the approximate time and location where the pilot initiated the descent. At 5,069 ft msl, the HRRR sounding indicated the temperature and dew point were about 16.8°C and about 0.4°C, respectively, with a relative humidity of 33 percent. At 6,076 ft msl, the HRRR sounding indicated the temperature and dew point were about 13.7°C and about -0.6°C, respectively, with a relative humidity of 37 percent. Review of the icing probability chart contained within Federal Aviation Administration Special Airworthiness Information Bulletin CE-09-35 indicated that the atmospheric conditions at the time of the accident were “conducive to serious icing at glide [idle] power.” FAA Advisory Circular 20-113 stated, "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 immediatelybefore 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." A review of the airplane owner’s manual revealed that, although the “Let-Down” checklist did not specify the application of carburetor heat, the “Before landing” checklist did state to apply carburetor heat before closing the throttle.

## Aircraft

- Registration: [N8337X](https://openairdocs.org/aircraft/N8337X), registered now, S/N 17248837, built 1961 (OpenAirDocs)
- Reported make and model: CESSNA 172 (C)
- Registry model: [Cessna 172C](https://openairdocs.org/model/cessna-172c) (registry code 2072408) (OpenAirDocs)
- Registry engine: [Continental 0-300 series](https://openairdocs.org/engine/continental-0-300-series) (registry code 17022, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 17248837
- Year built: 1961
- Airframe hours: 8614
- Engines: Continental O-300-D 145 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, June 2, 2023, 20 hours before
- Departed: SYM, Morehead, KY
- Destination: Same as departure
- Airport: HEF, Manassas Regional Airport/Harry P. Davis Field
- Equipment: Stall warning system, ADS-B, Auto-pilot, Electronic flight bag or handheld device

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 73; injuries: none; private; airplane ratings: single-engine land; medical: basicmed, unknown; last flight review November 21, 2022; seat: left; restraint: lap only; flight hours: 2,329 total, 2,329 in this make and model, 2,252 as pilot in command, 8 in the last 90 days, 6 in the last 30 days, 5 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Dusk
- Wind: 210° at 10 knots, gusting 15
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 77 °F, dew point 48 °F
- Altimeter: 29.70 inHg
- Observed at: KHEF
- METAR: KHEF 142356Z 21010G15KT 10SM CLR 25/09 A2970 RMK AO2 SLP062 T02500089 10278 20250 56011

## 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 20240414006539A](https://openairdocs.org/incident/20240414006539A), Apr 14, 2024: Cessna 172C, Manassas, VA, Substantial damage. Aircraft suffered an engine power loss during descent into landing at Manassas regional airport (hef). The PIC stated the engine stopped responding to throttle…

## Docket (10 files)

The files NTSB released with the investigation on January 14, 2025, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=194084. 29.5 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 10.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17107307&FileExtension=pdf&FileName=6120_1%20Master%20Form%20%20N8337X_Recd%204%2027%202024_11%20Pgs%20v02_Redacted-Rel.pdf
- Record of NTSB conversation (item 2, PDF, 4 pages, 184 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17820563&FileExtension=pdf&FileName=FINAL%20Record%20of%20Convo%20w%20Jim%20McKay%204%2016%202024%20v03_Redacted-Rel.pdf
- Excerpts from owner's manual (item 3, PDF, 2 pages, 129 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17867898&FileExtension=pdf&FileName=Excerpts%20Fm%20Owners%20Manual-Rel.pdf
- FAA inspector statement (item 4, PDF, 3 pages, 620 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17819994&FileExtension=pdf&FileName=FAA%20Inspector%20Statement_3%20Pgs_Redacted-Rel.pdf
- Memorandum for record - temperature and dew point information (item 5, PDF, 5 pages, 142 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17866005&FileExtension=pdf&FileName=FINAL%20Memo%20For%20Record%20-%20Weather%20Information%20v01_PSS-Rel.pdf
- Carburetor icing probability chart (item 6, PDF, 1 page, 327 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17866707&FileExtension=pdf&FileName=Carburetor%20Icing%20Probability%20Chart%20v01-Rel.pdf
- FAA chronological summary of flight communications (item 7, PDF, 2 pages, 688 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17866502&FileExtension=pdf&FileName=FAA%20Chron%20Summary%20of%20Flt%20Comms-Rel.pdf
- Federal aviation administration (FAA) automatic dependent surveillance a�� broadcast (ADS-B) tabular data (item 8, XLSX, 15.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17866512&FileExtension=xlsx&FileName=20240414_AB66E2_546392485_ADSB-Rel.xlsx
- Investigative photographs (item 9, PDF, 4 pages, 3 photos, 846 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17867197&FileExtension=pdf&FileName=Investigative%20Photos%20v01-Rel.pdf
- Release of aircraft wreckage, NTSB form 6120.15 (item 10, PDF, 1 page, 343 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17819560&FileExtension=pdf&FileName=Fully%20Exctd%20Wreckage%20Release%20Form_Redacted-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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