# NTSB ATL91LA139: Cessna 172P, N52433, Sylva, NC, July 22, 1991

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: July 22, 1991, 15:00 local (19:00 UTC)
- Place: Sylva, NC
- Coordinates: 35.369121, -83.219749 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=35.3691&lon=-83.2197&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 3 uninjured
- Status: Completed, report March 10, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 8441
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL91LA139
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/8441/pdf
- Page: https://openairdocs.org/ntsb/ATL91LA139

## Probable cause

THE PILOT'S IMPROPER IN-FLIGHT PLANNING, AND HIS FAILURE TO MAINTAIN A PROPER ALTITUDE WHILE MANEUVERING IN THE CANYON.  FACTOR(S) IN THIS ACCIDENT WERE: THE MOUNTAINOUS, BOX CANYON CONDITIONS, THE HIGH DENSITY ALTITUDE, AND THE DOWNDRAFT CONDITIONS AT THE TIME OF THE ACCIDENT.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- In flight collision with object, maneuvering
  - terrain condition - blind/box canyon (contributing factor)
  - terrain condition - mountainous/hilly (contributing factor)
  - weather condition - high density altitude (contributing factor)
  - in-flight planning/decision - improper, pilot in command (cause)
  - proper altitude - not maintained, pilot in command (cause)
  - object - tree(s)
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

THE PILOT AND TWO OBSERVERS WERE ON A MISSION TO SEARCH FOR MARIJUANA PLANTS GROWING IN A MOUNTAINOUS CANYON.  DURING SLOW FLIGHT, THEY ENCOUNTERED A DOWNDRAFT.  THE AIRSPEED DECAYED, AND ESCAPE ROUTES FROM THE CANYON WERE NO LONGER AVAILABLE.  THE PILOT SLOWED THE AIRCRAFT AND GUIDED IT INTO THE TREES.  FOLLOWING THE COLLISION WITH TREES, THE AIRPLANE FELL TO THE GROUND BELOW.  THE INVESTIGATION REVEALED THAT THE TEMPERATURE AT THE TIME WAS 92 DEGREES, AND THE AIRCRAFT WAS NEAR MAX GROSS WEIGHT. DENSITY ALTITUDE WAS ABOUT 6,000 FEET.  INSPECTION OF THE WRECKAGE REVEALED NO EVIDENCE OF MECHANICAL MALFUNCTION OR FAILURE, AND NO MECHANICAL PROBLEMS WERE REPORTED BY THE PILOT.

## Aircraft

- Registration: [N52433](https://openairdocs.org/deregistered/N52433-1991-12-16), registration cancelled 1991-12-16, S/N 17274518 (OpenAirDocs)
- Reported make and model: CESSNA 172P
- Registry model: [Cessna 172P](https://openairdocs.org/model/cessna-172p) (registry code 2072436) (OpenAirDocs)
- Category: Airplane
- Serial number: 17274518
- Airframe hours: 1467
- Engines: LYCOMING O-320-D2J 160 horsepower reciprocating
- Damage: Substantial damage
- Flight: Aerial observation, Part 91
- Operator: Civil Air Patrol, Inc.
- Registered owner: Civil Air Patrol, Inc.
- Airworthiness certificate: Standard, Normal; Standard, Utility
- Last inspection: 100 hour, May 22, 1991, 100 hours before
- Departed: 24A, SYLVA, NC

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 48; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 295 total, 50 in this make and model, 189 as pilot in command, 9 in the last 90 days, 4 in the last 30 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: 190° at 6 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 90 °F, dew point 66 °F
- Altimeter: 30.00 inHg
- Observed at: AVL, 32 nm away

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19910722029089A](https://openairdocs.org/incident/19910722029089A), Jul 22, 1991: Cessna 172P, Sylva, NC, Substantial damage. Civil air patrol marijuana search in blind canyon. Unable climb,hit trees. Weight temperature altitude factors.

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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