ANC93LA046

NTSB accident investigation · Piper PA-22 · Drift River, AK · March 20, 1993

Accident · No injuriesLimited investigationFinal report
Date
March 20, 1993, 11:23 local (15:23 UTC)
Place
Drift River, AK
Injuries
1 uninjured
Damage
Substantial damage
Phase of flight
Enroute
Aircraft
N72999Piper PA-22
Weather
Instrument (IMC) · Day
Status
Completed · report May 17, 1994
Report
Approved by Office Director
NTSB office
Alaska Regional Office
FAA report
19930320005779A
Case key
2331

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 pilots inadvertent VFR flight into IMC conditions. Factors were the rising terrain and the whiteout conditions.

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 collision with terrain/waterClimb
Terrain condition - risingFactor
Vfr flight into imc - inadvertentPilot in commandCause
Lack of familiarity with geographic areaPilot in command
Weather condition - whiteoutFactor
Nose overOther
Terrain condition - rough/uneven

Analysis

During the pilot's first attempt to fly through lake clark pass, he mistakenly turned up the wrong valley. When the already poor flight visibility continued to deteriorate, he began a 180 degree turn to get out of the valley, during which he entered whiteout conditions. When he saw mountains on both sides, he knew that he had missed the turn out of the valley. With no depth perception on which to estimate his altitude above the ground, he applied full engine power and maintained the best climb attitude. Very soon afterward the airplane collided with, and nosed over on, a glacier. During the preflight weather briefing the pilot was told that lake clark pass was forecast to be marginal VFR to IFR.

Factual narrative

History of flight

On March 20, 1993, at 1123 Alaska standard time, a wheel equipped Piper PA 22 airplane, N72999, encountered whiteout snow conditions, then nosed over after making a controlled crash landing on a glacier approximately 20 miles southwest of Drift River, Alaska. The commercial pilot, the sole occupant, was not injured, and the airplane was substantially damaged. The personal flight, operating under 14 CFR Part 91, departed Palmer, Alaska at 0938, and was destined for King Salmon, Alaska. Instrument meteorological conditions existed, and a VFR flight plan was filed.

Following the accident the pilot stated the following in part: "I was planning to fly through Lake Clark Pass en route to King Salmon, but missed my turn and flew up into the wrong valley. The ceiling and visibility kept getting lower so I decided to turn back. After doing a 180 degree turn the ceiling to my front was even lower, and the visibility was much lower because of the snow. So I decided to land on the glacier. Then I encountered whiteout snow conditions and lost all depth perception. I could still see about 3 miles up into the valley over the glacier. I touched down in snow about 2 feet deep, and the airplane nosed over onto it's back. I got a weather briefing by telephone about 45 minutes before taking off, from the automated flight service station in Kenai, Alaska. Marginal VFR conditions and turbulence was forecast. This was the first time I had tried to fly through the mountains this way. I guess I just used poor judgement."

Meteorological information

According to FAA records, at 0817 the pilot of N72999 telephoned the FAA Automated Flight Service Station (AFSS) in Kenai, Alaska, and obtained a weather briefing, then filed a VFR flight plan to King Salmon. During the briefing the pilot was told that the forecast (valid until 1800) called for Lake Clark Pass (elevation 1,000 feet above mean sea level) conditions to be marginal VFR to IFR. Ceilings in the Palmer, Anchorage and Kenai area were forecast to be below 1,000 feet and the visibility below 3 miles. Lower ceilings and visibility was forecast along and in the mountains.

Aircraft

Registration
N72999
Reported as
Piper PA-22
Category
Airplane
Serial number
22-6507
Airframe hours
3,095
Engine
Lycoming O-320-A2B, 150 horsepower, reciprocating
Damage
Substantial damage
Flight
Personal · Part 91
Operator
Johnson, Ronald B.
Registered owner
Johnson, Ronald B.
Airworthiness certificate
Standard, Normal
Last inspection
Annual · January 18, 1993 · 10 hours before
Departed
AK01 · Palmer, AK
Destination
AKN · King Salmon, AK
Flight plan
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
42
Certificate
Commercial
Airplane ratings
Single-engine land, Single-engine sea
Instrument ratings
Airplane
Medical
Class 2, Valid Medical--w/ waivers/lim
Seat
Left
Flight hours
484 total · 125 in this make and model · 395 as pilot in command · 18 in the last 90 days · 10 in the last 30 days · 4 in the last 24 hours

Weather

Conditions
Instrument (IMC) · Day
Wind
45° at 12 knots
Visibility
3 statute miles
Lowest ceiling
4,500 ft overcast
Temperature
19 °F

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 N72999 · 1

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