# NTSB CEN19LA260: Moth DH60GM, N919DH, Cortez, CO, August 8, 2019 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: August 7, 2019, 19:45 local (Aug 8, 2019, 01:45 UTC) - Place: Cortez, CO - Coordinates: 37.340232, -108.289253 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=37.3402&lon=-108.2893&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-climb to cruise: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: Minor injuries - Injuries: 2 minor - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: FAA - SAIBs cited in the narratives: [SAIB CE-09-35](https://openairdocs.org/saib/CE-09-35) (OpenAirDocs) - NTSB case key (mKey): 100026 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN19LA260 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/100026/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=100026 - Page: https://openairdocs.org/ntsb/CEN19LA260 ## Probable cause A partial loss of engine power due to carburetor ice accumulation, which resulted in a loss of altitude and impact with trees. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating): recip engine power section](https://openairdocs.org/ntsb-findings/01058520): Aircraft › Aircraft power plant · Related operating info (probable cause); cases with it: [Moth DH60GM, 1 case](https://openairdocs.org/ntsb-findings/01058520/cases.md?model=05632ZC), [All aircraft, 233 cases](https://openairdocs.org/ntsb-findings/01058520/cases.md) - [Action: incorrect action selection](https://openairdocs.org/ntsb-findings/02041010): Personnel issues › Action/decision · Pilot; cases with it: [Moth DH60GM, 1 case](https://openairdocs.org/ntsb-findings/02041010/cases.md?model=05632ZC), [All aircraft, 397 cases](https://openairdocs.org/ntsb-findings/02041010/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: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Moth DH60GM, 1 case](https://openairdocs.org/ntsb-events/342/sequence.md?model=05632ZC), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) ## Analysis The pilot reported that, shortly after takeoff, he reduced engine power to about 1,800 rpm and continued along a valley in a shallow climb. As the airplane approached a ridge, he turned the airplane back toward the valley and felt a “subtle sluggishness” of the airplane during the turn. He applied carburetor heat; however, it did not appear to have an effect, and he turned the carburetor heat off after about 20 seconds. The pilot continued toward an area of rising terrain because the engine was running smoothly and, he believed, producing enough power to return to the departure airport. The airplane descended and impacted trees, resulting in substantial damage to the wings, empennage, and fuselage. The recorded temperature and dew point at the time of the accident were conducive to the accumulation of serious carburetor icing at a glide power setting. Based on the available information, it is likely that the airplane lost partial power due to the accumulation of carburetor ice, which resulted in a gradual descent and impact with terrain. ## Factual narrative On August 7, 2019, about 1945 mountain daylight time, a Moth Aircraft Corp DH60GM airplane, N919DH, was substantially damaged when it was involved in an accident near Cortez, Colorado. The commercial pilot and passenger received minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that, shortly after takeoff, he reduced engine power to about 1,800 rpm and continued along a valley in a shallow climb. As the airplane approached a ridge, he turned the airplane back toward the valley and felt a “subtle sluggishness” of the airplane during the turn. He noted that the engine rpm was still about 1,800 rpm, and he applied carburetor heat. After about 20 seconds with the carburetor heat on, he noticed no perceptible change in the engine, so he turned off the carburetor heat to obtain maximum power. He stated that, even though the airspeed had decreased by about 10 mph and the engine did not seem to be producing full power, he did not believe the airplane was losing altitude; however, he stated that the airplane’s lack of a vertical speed indicator and sensitive altimeter made it difficult to ascertain a gradual loss of altitude, especially over uneven rising terrain. He continued toward an area of higher terrain, as the engine was running smoothly and he believed was producing enough power to return to the departure airport. The airplane subsequently impacted trees and terrain and the pilot and passenger egressed. The wings, fuselage, and empennage sustained substantial damage. At 1953, the weather reported at Cortez Municipal Airport (CEZ), Cortez, Colorado, about 16 miles west of the accident site, included a temperature of 80.6°F and a dew point 50°F. The calculated relative humidity at this temperature and dewpoint was 34.45 percent. Review of the icing probability chart contained within Federal Aviation Administration Special Airworthiness Information Bulletin CE-09-35 revealed the atmospheric conditions at the time of the accident were, "conducive to serious icing at glide power." ## Aircraft - Registration: [N919DH](https://openairdocs.org/aircraft/N919DH), registered now, S/N 120, built 1929 (OpenAirDocs) - Reported make and model: Moth Aircraft Corp DH60GM - Registry model: [Moth DH60GM](https://openairdocs.org/model/moth-dh60gm) (registry code 05632ZC) (OpenAirDocs) - Registry engine: [Dehav ENG GIPSY GRP 3](https://openairdocs.org/engine/dehav-eng-gipsy-grp-3) (registry code 20003, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 120 - Year built: 1929 - Airframe hours: 1228 - Engines: Dehavilland Gypsy II 120 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, May 3, 2019, 4 hours before - Departed: Mancos, CO - Destination: CEZ, Cortez, CO - Equipment: None ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 74; injuries: minor; commercial; airplane ratings: multi-engine land, single-engine land, single-engine sea; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review October 31, 2018; seat: front; flight hours: 7,875 total, 550 in this make and model, 7,875 as pilot in command, 37 in the last 90 days, 12 in the last 30 days, 0.3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 270° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 81 °F, dew point 50 °F - Altimeter: 30.11 inHg - Observed at: KCEZ, 16 nm away - METAR: KCEZ 080153Z AUTO 27005KT 10SM CLR 27/10 A3011 RMK AO2 SLP110 T02720100 ## 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 20190807014989A](https://openairdocs.org/incident/20190807014989A), Aug 7, 2019: Moth Aircraft Corp DH60GM, Cortez, CO, Substantial damage. The aircraft departed a private airstrip near mancos co. on a pleasure flight. Shortly after take off the pilot throttled back to 1800 RPM. And shortly after… ## Docket (3 files) The files NTSB released with the investigation on February 7, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=100026. 2.2 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 1.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12325555&FileExtension=pdf&FileName=Pilot%20Operator%20Aircraft%20Accident%20Report%20Form%20-%20CEN19LA260_Redacted-Rel.pdf - FAA carburetor icing probability chart (item 2, PDF, 1 page, 81 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12325854&FileExtension=pdf&FileName=Carb%20Ice%20Chart-Rel.pdf - Accident site photograph (item 3, PDF, 1 page, 1.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12326755&FileExtension=pdf&FileName=Docket%20Photos.dotx-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.