# NTSB CEN20CA094: Cessna 172, N370SP, Boulder, CO, February 20, 2020 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: February 20, 2020, 11:00 local (18:00 UTC) - Place: Boulder, CO - Coordinates: 40.04, -105.230003 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=40.0400&lon=-105.2300&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Loss of control on ground](https://openairdocs.org/ntsb-events/230) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report August 25, 2020 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Flight Standards District Office - NTSB case key (mKey): 100973 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN20CA094 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/100973/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=100973 - Page: https://openairdocs.org/ntsb/CEN20CA094 ## Probable cause The pilot's loss of directional control during the landing roll on the slush-covered runway. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Performance/control parameters: directional control](https://openairdocs.org/ntsb-findings/01062020): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Cessna 172S, 66 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md?model=2072439), [All aircraft, 3,958 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Cessna 172S, 206 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=2072439), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Runway/land/takeoff/taxi surface: snow/slush/ice covered surface](https://openairdocs.org/ntsb-findings/03023015): Environmental issues › Physical environment · Effect on operation (probable cause); cases with it: [Cessna 172S, 6 cases](https://openairdocs.org/ntsb-findings/03023015/cases.md?model=2072439), [All aircraft, 219 cases](https://openairdocs.org/ntsb-findings/03023015/cases.md) - [Perception/orientation/illusion: perception](https://openairdocs.org/ntsb-findings/02022040): Personnel issues › Psychological · Pilot; cases with it: [Cessna 172S, 2 cases](https://openairdocs.org/ntsb-findings/02022040/cases.md?model=2072439), [All aircraft, 61 cases](https://openairdocs.org/ntsb-findings/02022040/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing-landing roll: Loss of control on ground](https://openairdocs.org/ntsb-events/230) (defining event); cases with it: [Cessna 172S, 77 cases](https://openairdocs.org/ntsb-events/230/sequence.md?model=2072439), [All aircraft, 4,585 cases](https://openairdocs.org/ntsb-events/230/sequence.md) - [Landing-landing roll: Collision during takeoff/land](https://openairdocs.org/ntsb-events/490); cases with it: [Cessna 172S, 9 cases](https://openairdocs.org/ntsb-events/490/sequence.md?model=2072439), [All aircraft, 1,309 cases](https://openairdocs.org/ntsb-events/490/sequence.md) - [Landing-landing roll: Nose over/nose down](https://openairdocs.org/ntsb-events/096); cases with it: [Cessna 172S, 34 cases](https://openairdocs.org/ntsb-events/096/sequence.md?model=2072439), [All aircraft, 2,287 cases](https://openairdocs.org/ntsb-events/096/sequence.md) ## Analysis The pilot departed from a snow-packed runway, flew locally for about 2 hours, and then returned to land. The pilot stated that, while in the traffic pattern preparing to land, the runway still appeared to be snow-packed like it was during the departure. However, the runway was actually slush covered with patches of ice due to the morning sun melting the previously hard snow, and the airplane veered left during the landing roll. The pilot was unable to maintain directional control, and the airplane subsequently impacted a snowbank on the edge of the runway and nosed over, which resulted in substantial damage to both wings and the vertical stabilizer. ## Factual narrative The pilot and passenger departed from the uncontrolled airport on a snow packed runway and flew locally for about 2 hours, then returned to land. The pilot stated that while in the traffic pattern preparing to land, the runway appeared to be in the same condition as during the departure. Instead, the runway was slush covered due to the morning sun melting the snow and the airplane veered to the left during landing rollout. The pilot was unable to maintain directional control and the airplane subsequently impacted a snowbank on the edge of the runway and nosed over, which damaged both wings and the vertical stabilizer. ## Aircraft - Registration: [N370SP](https://openairdocs.org/aircraft/N370SP), registered now, S/N 172S9501, built 2003 (OpenAirDocs) - Reported make and model: Cessna 172 (S) - Registry model: [Cessna 172S](https://openairdocs.org/model/cessna-172s) (registry code 2072439) (OpenAirDocs) - Registry engine: [Lycoming IO-360-L2A](https://openairdocs.org/engine/lycoming-io-360-l2a) (registry code 41597, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 172S9501 - Year built: 2003 - Airframe hours: 4107 - Engines: Lycoming IO-360-L2A 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Rocky Mountain Flight Consultants Llc - Registered owner: Rocky Mountain Flight Consultants Llc - Airworthiness certificate: Standard, Normal - Last inspection: Annual, August 10, 2019, 91 hours before - Departed: BDU, Boulder, CO - Destination: BDU, Boulder, CO - Airport: BDU, Boulder Muni, runway 08, 4,100 × 75 ft, snow - Equipment: Auto-pilot, Stall warning system, ADS-B ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 33; injuries: none; foreign, private; airplane ratings: single-engine land; medical: class 3, without waivers/limitations; last flight review October 7, 2019; seat: left; restraint: 3-point; flight hours: 506 total, 120 in this make and model, 342 as pilot in command, 8 in the last 90 days, 5 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 23 °F, dew point 7 °F - Altimeter: 30.52 inHg - Observed at: KBDU, 1 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 20200220000709A](https://openairdocs.org/incident/20200220000709A), Feb 20, 2020: Cessna 172S, Boulder, CO, Substantial damage. On February 20, 2020 at approximately 1115 MST, N370SP, a Cessna 172S aircraft was substantially damaged during the landing rollout at the Boulder Municipal… ## Docket (2 files) The files NTSB released with the investigation on April 30, 2020, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=100973. 2.1 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40483290&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Photo at Accident Site (item 2, .PDF, 159 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40483291&FileExtension=.PDF&FileName=Photo%20at%20Accident%20Site-Master.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.