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Atlas / NTSB / GAA18CA538

NTSB CAROL · Event

Event GAA18CA538

2018-09-06 Carrabassett Valley, Maine, United States None 1 aircraft Status: Completed

Aircraft involved

Probable cause & findings

The pilot’s improper decision to initiate the flight in marginal visual flight rules over mountainous terrain, which resulted in an inadvertent encounter with instrument meteorological and downdraft conditions and the subsequent controlled flight into trees and terrain.

Factual narrative

The pilot reported that, after the skies cleared, he departed the airport following another airplane as a flight of two. During the flight they approached a ridge with no significant turbulence or issues. He added that suddenly they were in instrument meteorological conditions (IMC), and the lead airplane disappeared. He immediately changed course 10° to the left, and as he transitioned to instrument flying, the airplane encountered a downdraft. Shortly thereafter, the windscreen "filled with trees", that he estimated were less than a hundred feet away. He pitched the nose up to dissipate energy, and the airplane impacted the trees. 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 recommended that he should have flown his original flight plan, which was at a lower altitude, and he could have avoided unexpected and unpredicted winds and IMC conditions. The pilot reported that, after the sky cleared, he departed the airport following another airplane as a flight of two. During the flight, they approached a ridge with no significant turbulence or issues. He added that they were suddenly in instrument meteorological conditions (IMC), and the lead airplane disappeared. He immediately changed course 10° to the left, and as he transitioned to instrument flying, the airplane encountered a downdraft. Shortly thereafter, the windscreen "filled with trees," which he estimated were less than a 100 ft away. He pitched the nose up to dissipate energy, and the airplane subsequently impacted trees and terrain. 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 nearest official weather reporting station, which was 16 miles southwest of the accident site, reported, about the time of the accident, 10 miles visibility, temperature 70°F, dew point 66°F, a broken layer at 2,700 ft, a second broken layer at 3,200 ft, and an overcast layer at 4,100 ft. Although these were marginal visual flight rules conditions, given the mountainous terrain, the pilot should have expected that the mountain peaks may become obscured, and with a 4° temperature/dew point spread that visibility conditions could change rapidly. The pilot recommended that he should have flown his original flight plan, which was at a lower altitude so that he could have avoided unexpected and unpredicted winds and entering IMC. 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 Personnel issues-Action/decision-Info processing/decision-Decision making/judgment-Pilot - C
  • C Environmental issues-Conditions/weather/phenomena-Ceiling/visibility/precip-Below VFR minima-Decision related to condition - C
  • Environmental issues-Conditions/weather/phenomena-Ceiling/visibility/precip-Below VFR minima-Effect on personnel
  • Environmental issues-Physical environment-Terrain-Mountainous/hilly terrain-Effect on operation
  • Environmental issues-Conditions/weather/phenomena-Wind-Downdraft-Effect on operation

Verbatim from NTSB's published report. Source file NTSB_2018_GAA18CA538.txt. Findings + structured fields enriched from FAA avall.mdb. Full investigation docket on data.ntsb.gov ↗.

Related research

What the literature says.

Academic papers and agency reports matching this event's aircraft type or causal vocabulary (imc, turbulence). Sourced from NASA NTRS, NTSB Safety Studies, FAA CAMI, AOPA Air Safety Institute, Embry-Riddle Scholarly Commons, arXiv, and the Semantic Scholar academic graph.

Browse the full corpus — academia portal ↗