# NTSB WPR11CA337: Cessna 172N, N733BT, Porthill, ID, July 17, 2011 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: July 17, 2011, 15:00 local (22:00 UTC) - Place: Porthill, ID - Coordinates: 48.990276, -116.501945 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=48.9903&lon=-116.5019&mi=10 - Phase of flight: [Taxi](https://openairdocs.org/ntsb-phases/250) (OpenAirDocs' grouping) - Defining event: [Taxi-from runway: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report October 6, 2011 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: FEDERAL AVIATION ADMINISTRATION - NTSB case key (mKey): 81152 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR11CA337 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/81152/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=81152 - Page: https://openairdocs.org/ntsb/WPR11CA337 ## Probable cause The pilot's failure to maintain clearance from a pole. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Attention/monitoring: monitoring environment](https://openairdocs.org/ntsb-findings/02021545): Personnel issues › Psychological · Instructor/check pilot (probable cause); cases with it: [Cessna 172N, 6 cases](https://openairdocs.org/ntsb-findings/02021545/cases.md?model=2072434), [All aircraft, 809 cases](https://openairdocs.org/ntsb-findings/02021545/cases.md) - [Object/animal/substance: sign/marker](https://openairdocs.org/ntsb-findings/03022015): Environmental issues › Physical environment · Response/compensation (probable cause); cases with it: [Cessna 172N, 7 cases](https://openairdocs.org/ntsb-findings/03022015/cases.md?model=2072434), [All aircraft, 214 cases](https://openairdocs.org/ntsb-findings/03022015/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Taxi-from runway: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) (defining event); cases with it: [Cessna 172N, 15 cases](https://openairdocs.org/ntsb-events/900/sequence.md?model=2072434), [All aircraft, 1,556 cases](https://openairdocs.org/ntsb-events/900/sequence.md) - [Taxi-from runway: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Cessna 172N, 134 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=2072434), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The flight instructor reported that he was taxiing from the runway to the customs area located on the northern side of the airport, which required the airplane to taxi on a road between the runway and the U.S. Customs facility. The airplane's right wing struck a sign post on the right side of the road. The sign post dented the leading edge and bent internal wing ribs. The pilot reported no preimpact mechanical malfunctions or failures that would have precluded normal flight. ## Factual narrative The flight instructor reported that he was taxiing from the runway to the customs area located on the northern side of the airport, which required the airplane to taxi on a road between the runway and the US Customs facility. The airplane's right wing struck a sign post on the right side of the road. The sign post dented the leading edge and bent internal wing ribs. The pilot reported no preimpact mechanical malfunctions or failures that would have precluded normal flight. ## Aircraft - Registration: [N733BT](https://openairdocs.org/aircraft/N733BT), registered now, S/N 17268174, built 1976 (OpenAirDocs) - Reported make and model: CESSNA 172N - Registry model: [Cessna 172N](https://openairdocs.org/model/cessna-172n) (registry code 2072434) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 17268174 - Airframe hours: 4910 - Engines: LYCOMING O-320 SERIES 150 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Northern Air Inc - Registered owner: Northern Air Inc - Airworthiness certificate: Standard, Utility; Standard, Normal - Last inspection: Annual, December 14, 2010, 54 hours before - Departed: KSZT, Sandpoint, ID - Destination: KSZT, Sandpoint, ID - Flight plan: Unknown - Airport: 1S1, Eckhard International Airport, runway 33, 3,650 × 175 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 67; injuries: none; flight instructor, commercial; airplane ratings: single-engine land, single-engine sea; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review April 7, 2011; seat: right; flight hours: 4,288 total, 5,000 in this make and model, 4,070 as pilot in command, 141 in the last 90 days, 79 in the last 30 days, 4 in the last 24 hours - Student pilot; age 31; injuries: none; private; airplane ratings: single-engine land; medical: class 2, without waivers/limitations; last flight review August 12, 2002; seat: left; flight hours: 114 total, 80 in this make and model, 5 in the last 90 days, 5 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 136° at 3 knots - Visibility: 10 statute miles - Lowest ceiling: 12,000 ft broken - Temperature: 75 °F, dew point 52 °F - Altimeter: 29.77 inHg - Observed at: KSZT, 45 nm away ## Other investigations on N733BT (1) 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. - [NTSB WPR21LA192](https://openairdocs.org/ntsb/WPR21LA192), May 5, 2021: Cessna 172N (N733BT), Lewiston, ID, substantial damage. Probable cause: The pilot's failure to maintain directional control during taxiing in crosswind conditions, which resulted in a taxiway excursion and collision with a fence. ## Docket (4 files) The files NTSB released with the investigation on August 17, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=81152. 583 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 267 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40351744&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Photo 1 - Road used to taxi with pole that was impacted - Courtesy of FAA (item 2, .PDF, 76 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40351750&FileExtension=.PDF&FileName=Photo%201%20-%20Road%20used%20to%20taxi%20with%20pole%20that%20was%20impacted%20-%20Courtesy%20of%20FAA-Master.PDF - Photo 2 - Airplane right wing leading edge - Courtesy of FAA (item 3, .PDF, 176 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40351748&FileExtension=.PDF&FileName=Photo%202%20-%20Airplane%20right%20wing%20leading%20edge%20-%20Courtesy%20of%20FAA-Master.PDF - Photo 3 - Airplane right wing trailing edge - Courtesy of FAA (item 4, .PDF, 63 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40351749&FileExtension=.PDF&FileName=Photo%203%20-%20Airplane%20right%20wing%20trailing%20edge%20-%20Courtesy%20of%20FAA-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.