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NTSB accident investigation · Mitchell Derryle V Rans S 7 Courier · Cordova, AK · July 23, 2017

Accident · No injuriesData collectionFinal report
Date
July 23, 2017, 04:50 local (12:50 UTC)
Place
Cordova, AK
Injuries
1 uninjured
Damage
Substantial damage
Phase of flight
Takeoff
Aircraft
N6333YMitchell Derryle V Rans S 7 Courier
Defining event
Takeoff: Loss of lift
Weather
Visual (VMC) · Dawn
Status
Completed · report October 24, 2018
Report
Approved by Office Director
NTSB office
General Aviation Accidents
Parties
FAA
FAA report
20170723012609A
Case key
95669

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

On this page

Probable cause

The pilot’s improper decision to take off from a lake in gusting wind conditions, which resulted in a loss of airplane control.

Findings · 5

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.

Wind: downdraftEnvironmental issues › Conditions/weather/phenomena · Effect on operationMitchell Derryle V RANS S-7 COURIER: 1 caseAll aircraft: 178 casesProbable cause
Performance/control parametersAircraft › Aircraft oper/perf/capability · Not attained/maintainedMitchell Derryle V RANS S-7 COURIER: 1 caseAll aircraft: 1,269 casesProbable cause
Wind: gustsEnvironmental issues › Conditions/weather/phenomena · Effect on operationMitchell Derryle V RANS S-7 COURIER: 1 caseAll aircraft: 1,199 cases

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

The pilot of the float-equipped airplane reported that, following takeoff from a lake, he turned to left downwind about 750 ft above the water. He added that, once the turn was completed, the airplane encountered a strong downdraft, which "pushed [the] tail of [the airplane] down and away to [the] left," and the airplane began to descend. The pilot corrected with left rudder and was able to "straighten [the airplane] just prior to [the] right float tip contacting water." The airplane impacted the water, nosed over, and sank. The pilot egressed without further incident. The airplane sustained substantial damage to both wings. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. The pilot reported on the NTSB Form 6120.1 that the wind was from the east/southeast at 15 to 20 knots, gusting to 25 knots. The pilot reported a takeoff to the east. A review of recorded data from an automated weather observation station located about 7 nautical miles east of the accident, about the time of the accident, revealed winds calm; 10 statues miles visibility; few clouds at 600 ft, scattered clouds at 1,200 ft, and an overcast ceiling at 3,200 ft; temperature 54°F; dew point 54°F; and an altimeter setting at 30.19 inches of mercury. The computed density altitude at 750 ft was 322 ft. The Federal Aviation Administration's Airport Facility Directory for an airport 2 nautical miles west of the accident site stated, in part: "strong East winds, rwy subj to strong downdrafts."

Factual narrative

The pilot of the float-equipped airplane reported that, following takeoff from a lake, he turned left downwind about 750 ft. above the water. He added that, once the turn was completed, the airplane encountered a strong downdraft, which "pushed [the] tail of [the airplane] down and away to [the] left" and the airplane began to descend. The pilot corrected with left rudder and was able to "straighten [the airplane] just prior to [the] right float tip contacting water." The airplane impacted the water, nosed over, and sank. The pilot egressed without further incidence. The airplane sustained substantial damage to both wings. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. The pilot reported on the NTSB Form 6120.1 that the wind was from the east/southeast at 15 to 20 knots, gusting to 25 knots. The pilot reported a takeoff to the east. A review of recorded data from an automated weather observation station located about 7 nautical miles to the east of the accident, about the time of the accident, reported winds calm, 10 statues miles visibility, few clouds at 600 ft, scattered clouds at 1,200 ft, and an overcast ceiling at 3,200 ft, temperature 54°F, dew point 54°F, and an altimeter setting at 30.19" Hg. The computed density altitude at 750 ft. was 322 ft. The Federal Aviation Administration's Airport Facility Directory, for an airport 2 nautical miles west of the accident site, states in part: "strong East winds, rwy subj to strong downdrafts."

Aircraft

Registration
N6333Y
Reported as
Mitchell Derryle V Rans S 7 Courier (NO SERIES)
Category
Airplane, amateur-built
Serial number
0596188
Built
1998
Airframe hours
335.4
Engine
Rotax 912 UL, 105 horsepower, reciprocating
Damage
Substantial damage
Flight
Personal · Part 91
Airworthiness certificate
Special, Experimental (Special)
Last inspection
Annual · April 4, 2017
Departed
CKU · Cordova, AK
Destination
CKU · Cordova, AK
Airport
CKU · Cordova Muni
Equipment
Handheld GPS

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

As NTSB recorded them. NTSB leaves out names.

Role
Pilot
Age
49
Injuries
None
Certificate
Private
Airplane ratings
Single-engine sea, Single-engine land
Medical
Class 3, With waivers/limitations
Last flight review
April 11, 2017
Seat
Front
Restraint
3-point
Flight hours
387 total · 100 in this make and model · 233 as pilot in command · 108 in the last 90 days · 70 in the last 30 days · 7 in the last 24 hours

Weather

Conditions
Visual (VMC) · Dawn
Wind
Calm
Visibility
10 statute miles
Lowest ceiling
3,200 ft overcast
Temperature
54 °F, dew point 54 °F
Altimeter
30.19 inHg
Observed at
PACV, 7 nm away

Docket · 3

The files NTSB released with the investigation on September 13, 2018, on NTSB’s docket system: statements, records, photos and specialists’ reports. 1.5 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.