NTSB CAROL · Event
Event WPR11LA306
Aircraft involved
Probable cause & findings
The pilot’s failure to maintain clearance from terrain.
Factual narrative
On July 5, 2011, about 1050 Pacific daylight time, a Grumman AA-5, N1334R, collided with a tree and then terrain near Yacoit, Washington. The pilot/owner was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The commercial pilot and one passenger sustained serious injuries; the airplane sustained substantial damage from impact forces. The personal cross-country flight departed Grove Field, Camas, Washington, about 1040, with a planned destination of Grant County Regional/Ogilvie Field, John Day, Oregon. Visual meteorological conditions prevailed, and a visual flight rules (VFR) plan had been filed.The pilot reported that he departed straight out from runway 25, and opened his flight plan. He contacted Portland Approach Control for VFR flight following. Approach Control instructed him to remain clear of the class C airspace until they had positive radar identification. The pilot reversed his course, and the airplane was back abeam Grove Field. He remained on an easterly heading, and climbed to 2,400 feet. He observed rising terrain to the east. He decided to head back to the west, and maintained a reduced power setting and 100 miles per hour (mph) airspeed. Portland Approach contacted the pilot and stated that they had radar contact, and queried when he could accept a clearance to continue on course. He replied that he could proceed on course immediately, and indicated that his position was about 4 miles from the Gymme intersection, which was the first waypoint on his planned route of flight. He requested to cruise at 9,500 feet mean sea level (msl). He added full power, and began a climbing left turn to proceed on course. The pilot stated that he did not lose adequate terrain clearance at any time during the course reversal. The airplane was at full power climbing about 400-500 feet per minute. About 3,000 feet msl, he felt a small bump, and noted that the airspeed dropped to 80 mph. He verified that the throttle was in full, and then noticed that the airspeed dropped to 60 mph, which he said was 2 mph above the clean stall speed. While maintaining 60 mph with full power, the airplane began descending. At this point, the pilot noticed that a large fir tree was in the airplane's path; he stated that the airplane had about 1,000 feet of clearance above the tree's elevation prior to the bump. He started a gentle 4-degree bank turn to avoid the tree. The airplane descended until the right wing collided at midspan with a smaller unseen tree. The airplane came to rest in a gravel pit. Both the pilot and passenger sustained broken legs and lacerations; the pilot sustained broken fingers on his right hand as well, which he attributed to his maintaining the full throttle position until touchdown. The pilot stated that his preflight forecast was for calm conditions to 6,000 feet, and he did not encounter any turbulence during the flight. The Federal Aviation Administration (FAA) accident coordinator interviewed a bystander who came to the aid of the airplane's occupants. The bystander arrived about 5 minutes after the crash; he observed one person with a shattered ankle standing by the left side of the airplane, and one person still in the right seat. He noted that he saw a small fuel leak from under the left wing, and there was a fuel odor. Two FAA inspectors examined the airplane on scene. They observed a 5-gallon bucket under the left wing with about 1/2 inch of fuel in it. They opened the fuel caps on each wing tank, but could not determine if any or how much fuel was in the tanks. The FAA accident coordinator interviewed the pilot. The pilot indicated that he was maintaining a low altitude to avoid the controlled airspace above him. The pilot initiated a left turn to avoid rising terrain ahead, and could not estimate the altitude above ground level (agl). The pilot did not think that winds were a factor, but that the airplane might have been too low at the intuition of the turn. The FAA accident coordinator interviewed the passenger. The passenger stated that he was looking around enjoying the flight and the scenery as they were heading up a valley. He did recall looking at the engine gauges as this time, and the engine rpm was in the green operating range. The engine sounded good up until the end. As he looked back to the front of the airplane, he and the pilot almost simultaneously stated that they were not going to make it. The pilot indicated that they would be all right if they could get between two trees. The airplane hit one of the trees, and then the ground. The passenger was not sure what direction the airplane was headed or if it was turning. He felt that all changes to the airplane's flight path were controlled at all times, and did not think that there were air pockets, updrafts, or downdrafts that affected the airplane's flight path. The pilot reported that the airplane was climbing to cruise altitude up a valley in mountainous terrain when he felt a "small bump" and that the airplane subsequently began descending. While maintaining a low altitude to avoid overlying controlled airspace, he initiated a left turn to avoid rising terrain ahead, but a wing collided with a tree. The airplane came to rest in a gravel pit. The pilot reported no preimpact mechanical malfunctions or failures with the airplane that would have precluded normal operation. 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 Aircraft-Aircraft oper/perf/capability-Performance/control parameters-Altitude-Not attained/maintained - C
- C Personnel issues-Action/decision-Action-Incorrect action performance-Pilot - C
- — Environmental issues-Physical environment-Terrain-Mountainous/hilly terrain-Awareness of condition
Verbatim from NTSB's published report. Source file
NTSB_2011_WPR11LA306.txt.
Findings + structured fields enriched from FAA avall.mdb.
Full investigation docket on
data.ntsb.gov ↗.
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Related research
What the literature says.
Academic papers and agency reports matching this event's aircraft type or causal vocabulary (stall, 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.
- Embry-Riddle Scholarly Commons 2021 · Journal article (IJAAA)
Comparative Study on the Prediction of Aerodynamic Characteristics of Mini - Unmanned Aerial Vehicle with Turbulence Models
When dealing with CFD simulations the turbulent nature is seen on most of the engineering flows and these flows need to be solved.
- arXiv 2020 · arXiv preprint
Numerical Simulation of Iced Wing Using Separating Shear Layer Fixed Turbulence Models
Aerodynamic prediction of glaze ice accretion on airfoils and wing is studied using the Reynolds-averaged Navier-Stokes method.
- NASA NTRS 2019 · Conference Paper
Prediction of stall and post-stall behavior of airfoils at low and high Reynolds numbers
An interactive boundary-layer method, together with the e(super n)-approach to the calculation of transition, has been used to predict the stall and post-stall behavior of airfoils at low and high Rey…
- arXiv 2026 · arXiv preprint
Direct Numerical Simulations of Ice-Ocean Boundary Turbulence
Turbulent heat and freshwater transport at ice-ocean interfaces controls glacier and iceberg melt rates, yet the underlying physics remains poorly constrained.
- NASA NTRS 2026 · Conference Paper
Computational Analysis of Steady State Aerodynamics of Transonic Truss-Braced Wing Configuration in Deep Stall
This study presents a computational investigation of steady state aerodynamics of the Subsonic Ultra-Green Aircraft Research (SUGAR) Transonic Truss-Braced Wing (TTBW) configuration over a wide range …
- Embry-Riddle Scholarly Commons 2025 · Journal article (JAAER)
Political Turbulence and Aviation Safety: A Cross-National Analysis of Political Stability's Effects on Aviation Accidents
To what extent does political stability affect aviation safety? This research aims to link domestic political conditions and public safety through the consideration of aviation accident frequency.
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