# NTSB WPR11CA308: Piper PA-18, N23TT, Enumclaw, WA, July 2, 2011 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Data collection · Final report - Date: July 2, 2011, 16:00 local (23:00 UTC) - Place: Enumclaw, WA - Coordinates: 47.013053, -121.535003 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=47.0131&lon=-121.5350&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing: Windshear or thunderstorm](https://openairdocs.org/ntsb-events/390) - Highest injury: Minor injuries - Injuries: 2 minor - Status: Completed, report October 4, 2011 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 80881 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR11CA308 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/80881/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=80881 - Page: https://openairdocs.org/ntsb/WPR11CA308 ## Probable cause The pilot's failure to maintain an adequate airspeed during an encounter with a mountain wave and downdraft landing. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Performance/control parameters: airspeed](https://openairdocs.org/ntsb-findings/01062010): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Piper PA-18, 5 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md?model=7101802), [All aircraft, 1,681 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Piper PA-18, 21 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=7101802), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Wind: windshear](https://openairdocs.org/ntsb-findings/03034020): Environmental issues › Conditions/weather/phenomena · Response/compensation (probable cause); cases with it: [Piper PA-18, 1 case](https://openairdocs.org/ntsb-findings/03034020/cases.md?model=7101802), [All aircraft, 90 cases](https://openairdocs.org/ntsb-findings/03034020/cases.md) - [Wind: downdraft](https://openairdocs.org/ntsb-findings/03034035): Environmental issues › Conditions/weather/phenomena · Response/compensation (probable cause); cases with it: [Piper PA-18, 1 case](https://openairdocs.org/ntsb-findings/03034035/cases.md?model=7101802), [All aircraft, 178 cases](https://openairdocs.org/ntsb-findings/03034035/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing: Windshear or thunderstorm](https://openairdocs.org/ntsb-events/390) (defining event); cases with it: [Piper PA-18, 1 case](https://openairdocs.org/ntsb-events/390/sequence.md?model=7101802), [All aircraft, 224 cases](https://openairdocs.org/ntsb-events/390/sequence.md) - [Landing-flare/touchdown: Hard landing](https://openairdocs.org/ntsb-events/092); cases with it: [Piper PA-18, 4 cases](https://openairdocs.org/ntsb-events/092/sequence.md?model=7101802), [All aircraft, 2,102 cases](https://openairdocs.org/ntsb-events/092/sequence.md) - [Landing-flare/touchdown: Runway excursion](https://openairdocs.org/ntsb-events/300); cases with it: [Piper PA-18, 8 cases](https://openairdocs.org/ntsb-events/300/sequence.md?model=7101802), [All aircraft, 3,643 cases](https://openairdocs.org/ntsb-events/300/sequence.md) - [Landing-landing roll: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Piper PA-18, 19 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=7101802), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot reported that he was making an approach to an airstrip for a brief stop. He overflew the field and determined the wind was variable from the north and started his approach. On final approach he noticed an above average loss of altitude and speed due to a large mountain wave coming over the foothills to the west. He added power to compensate for the downdraft and continued on his landing approach. Once clear of some trees at the approach end of the runway he reduced the power to idle and was again pushed down by another downdraft. The pilot then added full power to arrest the airplane's descent but he did not have enough speed at that time to avoid a hard landing. The airplane slid off the runway and into a guard railing. The fuselage tubular frame sustained substantial damage. The pilot reported no mechanical problems that would have precluded normal operation. ## Factual narrative The pilot reported that he was making an approach to an airstrip for a brief stop. He overflew the field and determined the wind was variable from the north and started his approach. On final he noticed an above average loss of altitude and speed due to a large mountain wave coming over the foothills to the west. He added power to compensate for the downdraft and continued on his landing approach. Once clear of some trees at the approach end of the runway he reduced the power to idle and was again pushed down by another downdraft. The pilot then added full power to arrest the airplane's decent but he did not have enough speed at that time to avoid a hard landing. The airplane slid off the runway and into a guard railing, which substantially damaged the fuselage tubular frame. ## Aircraft - Registration: [N23TT](https://openairdocs.org/aircraft/N23TT), registered now, S/N 18-6684 (OpenAirDocs) - Reported make and model: PIPER PA-18 - Registry model: [Piper PA-18](https://openairdocs.org/model/piper-pa-18) (registry code 7101802) (OpenAirDocs) - Registry engine: [Continental C90 series](https://openairdocs.org/engine/continental-c90-series) (registry code 17009, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 18-6684 - Airframe hours: 4420 - Engines: Lycoming O-320-A2B 150 horsepower reciprocating - Damage: Destroyed - Flight: Personal, Part 91 - Operator: Juliett Limited - Registered owner: Juliett Limited - Airworthiness certificate: Standard, Normal; Standard, Utility - Last inspection: Annual, January 21, 2011, 10 hours before - Departed: 21W, Enumclaw, WA - Destination: 21W, Enumclaw, WA - Flight plan: Unknown - Airport: 21W, Ranger Station, runway 33, 2,875 × 30 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 32; injuries: minor; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; last flight review October 6, 2010; seat: left; flight hours: 174 total, 85 in this make and model, 174 as pilot in command, 3 in the last 90 days ## Weather - Conditions: Visual (VMC), Day - Wind: variable at 4 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 81 °F, dew point 43 °F - Altimeter: 29.88 inHg - Observed at: RNT, 40 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 20110702013889A](https://openairdocs.org/incident/20110702013889A), Jul 2, 2011: Piper PA-18, Enumclaw, WA, Substantial damage. Pilot stated on landing approach gust of wind and down draft caused a/c to vear to right of runway and touch down in gravel area heading aaprox 60DEGREES to… ## Other investigations on N23TT (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 SEA86LA224](https://openairdocs.org/ntsb/SEA86LA224), Aug 24, 1986: Piper PA-18-150 (N23TT), Kent, WA, substantial damage ## Docket (3 files) The files NTSB released with the investigation on July 22, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=80881. 1.9 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1 photo, 426 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40351045&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Photo 1 - Skid marks. Photo from FAA (item 2, .PDF, 897 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40351054&FileExtension=.PDF&FileName=Photo%201%20-%20Skid%20marks.%20Photo%20from%20FAA-Master.PDF - Photo 2 - Aircraft damage. Photo from FAA (item 3, .PDF, 585 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40351055&FileExtension=.PDF&FileName=Photo%202%20-%20Aircraft%20damage.%20Photo%20from%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.