ANC97LA100

NTSB accident investigation · Piper PA-18-160 · Cantwell, AK · July 8, 1997

Accident · Minor injuriesLimited investigationFinal report
Date
July 8, 1997, 13:30 local (21:30 UTC)
Place
Cantwell, AK
Injuries
2 minor
Damage
Substantial damage
Phase of flight
Enroute
Aircraft
N3952ZPiper PA-18-160
Weather
Visual (VMC) · Day
Status
Completed · report November 10, 1998
Report
Approved by Office Director
NTSB office
Alaska Regional Office
FAA report
19970708017179A
Case key
3023

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 failure to maintain sufficient altitude to clear terrain. Factors were exceeding the airplane's maximum allowable gross weight, and downdrafts and turbulence associated with wind flowing across a mountain ridge.

Sequence of events

NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.

In flight encounter with weatherClimb - to cruise
Weather condition - turbulence,terrain inducedFactor
Weather condition - downdraftFactor
In flight collision with terrain/waterManeuvering - turn to reverse direction
Terrain condition - blind/box canyon
Altitude/clearance - not maintainedPilot in commandCause
Aircraft weight and balance - exceededPilot in commandFactor

Analysis

The air taxi pilot and passenger were approaching a mountain ridge from below. Both occupants described conditions favoring a downslope wind and turbulence at the ridge. The pilot attempted to turn when he realized they would not clear the ridge, but the airplane descended and impacted terrain. The airplane was estimated to weigh 1,827 pounds at the time of the last takeoff. The maximum takeoff weight is 1,760 pounds. The elevation at the accident site was 4,500 feet msl.

Factual narrative

On July 8, 1997, about 1330 Alaska daylight time, a Piper PA-18-160 airplane, N3952Z, sustained substantial damage when it struck a ridge about 15 nautical miles southeast of Cantwell, Alaska, at position 63-13.89 north latitude, 148-34.88 west longitude. The commercial certificated pilot and single passenger sustained minor injuries. The airplane was operated by Ray H. Atkins of Cantwell, Alaska, doing business as Ray Atkins, Registered Guide. The flight was conducted under 14 CFR Part 135 in visual meteorological conditions.

The passenger stated to a Federal Aviation Administration inspector during an interview, that the flight was a return leg to Cantwell from Soule lake, and the route of flight was chosen to view mountainous terrain and wildlife. The airplane was flown into a canyon, and while attempting to climb over a ridge, struck terrain. The passenger stated to the NTSB investigator that the airplane was paralleling a ridge on the right side, and climbing to cross a ridge which was ahead of them. When it appeared that the airplane would not clear the ridge, the pilot turned the airplane left and attempted to accelerate. The occupants said it felt as if the plane fell, and then struck the ground hard. It rolled down the mountainside, coming to rest at 4,500 feet msl. The passenger stated that while awaiting rescue, the pilot said several times, " I should have been higher. I was too low. I turned and the downdraft got us."

The pilot wrote in his pilot/operator report that the airplane was climbing at 70 miles per hour, along the right side of a valley. He was heading northeast, and attempting to clear a ridge. He stated that he turned the airplane to the left, away from the ridge. The airspeed dropped to zero, he applied power, and lowered the airplane's nose to gain airspeed. The pilot said the left float caught the ground and pulled the left wing into the hillside.

The pilot estimated prevailing winds were from the northeast at thirty miles per hour. The passenger said that the winds at the crash site were light from the northeast. This location was at a lower elevation, and downwind of the pass which they had been attempting to clear.

The injured pilot was extracted from the wreckage by the passenger. He directed the passenger to turn off the airplane electrical master switch, and activate the Emergency Locator Transmitter. The survivors were located at 1600. At 1730 a helicopter attempted to land but was unable due to the steep terrain. At 2000 the survivors were recovered via hoist by an Alaska Air National Guard helicopter and transported to Anchorage.

The empty weight of the airplane is 1,261 pounds according to the loading schedule provided by the pilot. The pilot estimated the fuel on board at the last takeoff to be eighteen gallons of 100 low lead aviation gasoline. His FAA medical certificate dated June 6, 1997, states the pilot weighed 215 pounds. The passenger estimates his weight to be 220 pounds. Baggage estimated by the pilot and passenger was seven pounds. Eight quarts of oil are estimated to be 16 pounds. The estimated total weight at the time of the last takeoff is 1,827 pounds. The maximum allowable takeoff weight is 1,760 pounds.

Aircraft

Registration
N3952Z
Reported as
Piper PA-18-160
Category
Airplane
Serial number
18-7810
Airframe hours
5,652
Engine
Lycoming O-320-A2B, 160 horsepower, reciprocating
Damage
Substantial damage
Flight
Part 135
Registered owner
Ray H. Atkins
Airworthiness certificate
Standard, Normal
Last inspection
Annual · April 22, 1997 · 25 hours before
Departed
Soule Lake, AK
Destination
PATW · Gas Lake, AK
Flight plan
Company VFR

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
53
Certificate
Commercial
Airplane ratings
Single-engine land, Single-engine sea
Instrument ratings
Airplane
Medical
Class 2, Valid Medical--w/ waivers/lim
Seat
Front
Flight hours
14,800 total · 6,100 in this make and model

Weather

Conditions
Visual (VMC) · Day
Wind
180° at 6 knots
Visibility
15 statute miles
Lowest ceiling
20,000 ft overcast
Temperature
61 °F, dew point 48 °F
Altimeter
29.00 inHg
Observed at
PAT, 15 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.

Other investigations on N3952Z · 4

Matched to the same aircraft by N-number and date.