# NTSB CEN11LA045: Walker Kenneth Sonex, N234KS, San Angelo, TX, October 29, 2010 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: October 29, 2010, 14:30 local (19:30 UTC) - Place: San Angelo, TX - Coordinates: 31.594999, -100.55722 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=31.5950&lon=-100.5572&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Defining event: [Initial climb: Loss of control in flight](https://openairdocs.org/ntsb-events/240) - Highest injury: Serious injuries - Injuries: 2 serious - Status: Completed, report October 3, 2011 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA FSDO - NTSB case key (mKey): 77697 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN11LA045 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/77697/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=77697 - Page: https://openairdocs.org/ntsb/CEN11LA045 ## Probable cause The pilot's loss of airplane control. Contributing to the accident was the pilot's impairment due to alcohol. ## 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: [Walker Kenneth SONEX, 1 case](https://openairdocs.org/ntsb-findings/01062020/cases.md?model=05617E6), [All aircraft, 3,958 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md) - [Impairment/incapacitation: alcohol](https://openairdocs.org/ntsb-findings/02012015): Personnel issues › Physical · Pilot (probable cause); cases with it: [Walker Kenneth SONEX, 1 case](https://openairdocs.org/ntsb-findings/02012015/cases.md?model=05617E6), [All aircraft, 87 cases](https://openairdocs.org/ntsb-findings/02012015/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Walker Kenneth SONEX, 1 case](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=05617E6), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Initial climb: Loss of control in flight](https://openairdocs.org/ntsb-events/240) (defining event); cases with it: [Walker Kenneth SONEX, 1 case](https://openairdocs.org/ntsb-events/240/sequence.md?model=05617E6), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md) - [Uncontrolled descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Walker Kenneth SONEX, 1 case](https://openairdocs.org/ntsb-events/470/sequence.md?model=05617E6), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis A private pilot and a student pilot were departing a private airfield when they heard a loud bang. The airplane climbed to 100 to 200 feet above ground level when it began to vibrate. The private pilot, who was operating the airplane, remarked that he did not have control of the airplane. The student pilot recalled that the airplane entered a nose-high left turn prior to ground impact. An examination of the airplane and engine did not reveal any preimpact anomalies. There was no evidence of a material failure to explain the loud noise prior to the accident; the source of the loud noise was not determined. An alcohol screen conducted on a sample of the private pilot's blood revealed a 0.11 percent blood alcohol level. ## Factual narrative On October 29, 2010, approximately 1430 central daylight time, a Walker Sonex airplane, N234KS, impacted terrain near San Angelo, Texas. The private pilot and student pilot were seriously injured. The airplane sustained substantial crushing damage to the wings and fuselage. The airplane was registered to and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the flight, which operated without a flight plan. The flight was originating from a private airstrip at the time of the accident. According to a statement provided by the student pilot, the flight was the second flight the two pilots had flown that day. The private pilot was controlling the airplane during the accident flight. At an estimated 100 feet above ground level the student pilot heard a loud noise come from the back of the airplane like they had struck an object. The airplane began to vibrate and the private pilot told the student pilot that he did not have control of the airplane. The student pilot recalled that the engine appeared to be operating at full power with his last recollection that the airplane in a left turn with a nose high attitude before impacting terrain. An inspection of the airframe and engine by a responding Federal Aviation Administration inspector did not reveal any preimpact anomalies which would have precluded normal operation of the aircraft. Impact signatures were consistence with an aircraft stall during the initial climb. There was no evidence of a material failure to explain the loud noise prior to the accident; the source of the loud noise was not determined. A blood sample obtained from the private pilot by the Texas Department of Public Safety (DPS) revealed an intoxication level of 0.11 blood alcohol content. ## Aircraft - Registration: [N234KS](https://openairdocs.org/aircraft/N234KS), registered now, S/N 0579, built 2004 (OpenAirDocs) - Reported make and model: WALKER KENNETH SONEX - Registry model: [Walker Kenneth SONEX](https://openairdocs.org/model/walker-kenneth-sonex) (registry code 05617E6) (OpenAirDocs) - Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 0579 - Airframe hours: 92 - Engines: AMA/EXPR UNKNOWN ENG 92 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, September 1, 2010 - Departed: San Angelo, TX - Destination: San Angelo, TX ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 70; injuries: serious; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; seat: right - Student pilot; age 64; injuries: none; student; medical: class 3, with waivers/limitations; seat: left; flight hours: 44 total, 39 in this make and model, 44 as pilot in command ## Weather - Conditions: Visual (VMC), Day - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 73 °F, dew point 27 °F - Altimeter: 30.29 inHg - Observed at: SJT, 15 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 20101029049259A](https://openairdocs.org/incident/20101029049259A), Oct 29, 2010: Walker Kenn SONEX, San Angelo, TX, Destroyed. On October 29, 2010, N234KS, a Sonex experimental homebuilt aircraft lost control and crashed. The pilot said he lost pitch control of the aircraft. Damage was… ## Docket (3 files) The files NTSB released with the investigation on July 8, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=77697. 1.1 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 796 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40339243&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Photo: Side view (item 2, .PDF, 125 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40350436&FileExtension=.PDF&FileName=Photo%3A%20Side%20view-Master.PDF - Photo: Left side (item 3, .PDF, 144 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40350437&FileExtension=.PDF&FileName=Photo%3A%20Left%20side-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.