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Atlas / NTSB / GAA17CA440

NTSB CAROL · Event

Event GAA17CA440

2017-07-23 Cordova, Alaska, United States Airport · CKU None 1 aircraft Status: Completed

Aircraft involved

Probable cause & findings

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

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." 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." Source: NTSB Aviation Accident Database Retrieved: 2026-02-12

NTSB Findings

Hierarchical cause / factor breakdown from the FAA bulk avdata database. Each finding tagged C (Cause) or F (Factor).

  • C Environmental issues-Conditions/weather/phenomena-Wind-Downdraft-Effect on operation - C
  • C Personnel issues-Task performance-Use of equip/info-Aircraft control-Pilot - C
  • C Aircraft-Aircraft oper/perf/capability-Performance/control parameters-(general)-Not attained/maintained - C
  • C Personnel issues-Action/decision-Info processing/decision-Decision making/judgment-Pilot - C
  • Environmental issues-Conditions/weather/phenomena-Wind-Gusts-Effect on operation

Verbatim from NTSB's published report. Source file NTSB_2017_GAA17CA440.txt. Findings + structured fields enriched from FAA avall.mdb. Full investigation docket on data.ntsb.gov ↗.