CEN11LA045

NTSB accident investigation · Walker Kenneth Sonex · San Angelo, TX · October 29, 2010

Accident · Serious injuriesLimited investigationFinal report
Date
October 29, 2010, 14:30 local (19:30 UTC)
Place
San Angelo, TX
Injuries
2 serious
Damage
Substantial damage
Phase of flight
Initial climb
Aircraft
N234KSWalker Kenneth Sonex
Defining event
Initial climb: Loss of control in flight
Weather
Visual (VMC) · Day
Status
Completed · report October 3, 2011
Report
Approved by Office Director
NTSB office
Central Region
Parties
FAA FSDO
FAA report
20101029049259A
Case key
77697

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

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Probable cause

The pilot's loss of airplane control. Contributing to the accident was the pilot's impairment due to alcohol.

Findings · 3

NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.

Performance/control parameters: directional controlAircraft › Aircraft oper/perf/capability · Not attained/maintainedWalker Kenneth SONEX: 1 caseAll aircraft: 3,958 casesProbable cause
Use of equip/info: aircraft controlPersonnel issues › Task performance · PilotWalker Kenneth SONEX: 1 caseAll aircraft: 9,295 casesProbable cause

Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.

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
Reported as
Walker Kenneth Sonex
Category
Airplane, amateur-built
Serial number
0579
Airframe hours
92
Engine
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

Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.

Flight crew · 2

As NTSB recorded them. NTSB leaves out names.

Role
Pilot
Age
70
Injuries
Serious
Certificate
Private
Airplane ratings
Single-engine land
Medical
Class 3, With waivers/limitations
Seat
Right
Role
Student pilot
Age
64
Injuries
None
Certificate
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

Docket · 3

The files NTSB released with the investigation on July 8, 2011, on NTSB’s docket system: statements, records, photos and specialists’ reports. 1.1 MB in all.

FAA reports on this event · 1

The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.