ANC01TA035

NTSB accident investigation · Robinson R-44 · Chickaloon, AK · February 4, 2001

Accident · No injuriesFinal report
Date
February 4, 2001, 09:30 local (13:30 UTC)
Place
Chickaloon, AK
Injuries
3 uninjured
Damage
Substantial damage
Phase of flight
Approach
Aircraft
N7183PRobinson R-44
Weather
Visual (VMC) · Day
Status
Completed · report August 21, 2001
Report
Approved by Office Director
NTSB office
Alaska Regional Office
Parties
FAA-ANC-FSDO 03
FAA report
20010204039949A
Case key
51446

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

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Probable cause

The pilot's collision with terrain due to his inadequate planning of the approach, and his failure to maintain the helicopter's main rotor RPM during a go-around. Factors in the accident were a tailwind, flat lighting conditions, and snow-covered terrain.

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/waterGo-around (vfr)
Rotor rpm - not maintainedPilot in commandCause
Weather condition - tailwindFactor
Planned approach - inadequatePilot in commandCause
Light condition - otherFactor
Terrain condition - snow coveredFactor
Roll overGo-around (vfr)

Analysis

The pilot was transporting two search and rescue volunteers and their equipment to the scene of an avalanche in a float-equipped helicopter. A helicopter landing zone (heli spot) had been established the evening before the accident, near the toe of the avalanche. The heli spot had been used by a military helicopter, and was marked by small flags. The surface of the snow at the heli spot had been dusted by red powder. The pilot of the accident helicopter had not landed at the heli spot before. The heli spot was located at 5,300 feet msl, near the bottom of a small valley. The pilot began his landing approach toward the west. Although the weather conditions were clear, the pilot said the lighting conditions in the valley provided little contrast (flat light). The pilot said that as he began to add power near the termination of the landing approach, the low rotor warning horn sounded, and he noticed that the main rotor gauge was indicating 92 to 94 percent. He reduced collective pitch, ensured the throttle was full open, and began to initiate a go-around toward the west, an area of lower terrain. The helicopter continued to descend, and the right front portion of the landing gear float assembly contacted the snow. About the same time, the main rotor contacted the slope of a small, snow-covered hill, to the right of the helicopter. The helicopter then rolled onto its right side. After the accident, the pilot said he noted that the wind was blowing about 8 knots from the east.

Factual narrative

On February 4, 2001, about 0930 Alaska standard time, a float-equipped Robinson R-44 helicopter, N7183P, sustained substantial damage while landing in a remote area, about 35 miles east-northeast of Chickaloon, Alaska. The helicopter was being operated as a visual flight rules (VFR) government-operated flight under Title 14, CFR Part 91, when the accident occurred. The helicopter was operated by the State of Alaska, Department of Public Safety. The airline transport certificated pilot, and the two passengers, were not injured. Visual meteorological conditions prevailed. The flight originated at the Eureka Lodge, Eureka, Alaska, about 0915.

During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on February 4th, the pilot, who is the supervisor for the State of Alaska's Aircraft Section, reported that he was transporting two search and rescue volunteers and their equipment to the scene of an avalanche. The avalanche was about 11.3 miles south-southeast of the Eureka Lodge. Utilizing the accident helicopter, the pilot had been involved in search operations at the avalanche site the evening before the accident. A helicopter landing zone (heli spot) had been established the evening before the accident, near the toe of the avalanche. The heli spot had been used by a military helicopter, and was marked by small flags. The surface of the snow at the heli spot had been dusted by red powder. The pilot of the accident helicopter had not landed at the heli spot before. The heli spot was located at 5,300 feet msl, near the bottom of a small valley.

The pilot said he began his landing approach toward the west. Although the weather conditions were clear, the pilot said the lighting conditions in the valley provided little contrast (flat light). The pilot said that as he began to add power near the termination of the landing approach, the low rotor warning horn sounded, and he noticed that the main rotor gauge was indicating 92 to 94 percent. He reduced collective pitch, ensured the throttle was full open, and began to initiate a go-around toward the west, an area of lower terrain. The helicopter continued to descend, and the right front portion of the landing gear float assembly contacted the snow. About the same time, the main rotor contacted the slope of a small, snow-covered hill, to the right of the helicopter. The helicopter then rolled onto its right side. After the accident, the pilot said he noted that the wind was blowing about 8 knots from the east.

The passengers on board the helicopter reported hearing the low rotor warning horn as the helicopter was about 100 feet above the ground in a small gully area. They said there was little contrast to define the terrain. They reported the temperature as 25 degree F.

The pilot said the temperature was 10 degrees F. The helicopter has a gross weight of 2,400 pounds. A postaccident review of the helicopter's loading and performance calculations revealed the helicopter was loaded to about 100 pounds below maximum gross weight. According to the manufacturer's performance charts, at 2,300 pounds, the out-of-ground effect hover ceiling at 10 degrees is about 5,300 feet, at 25 degrees, the hover ceiling is about 4,700 feet. The in-ground-effect hover ceiling (a two foot hover height) at 10 degrees is about 8,400 feet, at 25 degrees, the hover ceiling is about 7,800 feet.

The State of Alaska's Aircraft Manual, Revised March 2000, Section IV, (B) 1., lists pilot qualifications. The manual indicates that the minimum experience in the accident helicopter (Robinson R-44) is 200 hours. In the NTSB Pilot/Operator report submitted by the pilot, the pilot indicated having accrued 381 hours in helicopters, with 221 hours in a Robinson R-44. Section IV, (B) 9. b), lists pilot currency requirements by stating that helicopter pilots must, within the last 90 days, have at least 10 flight hours. The pilot indicated he accured 9.4 hours in the accident helicopter in the previous 90 days, 7.1 hours in the previous 30 days, and 2.4 hours in the previous 24 hours.

Aircraft

Registration
N7183P
Reported as
Robinson R-44
Category
Helicopter
Serial number
0535
Airframe hours
685
Engine
Lycoming O-540-F1B5, 260 horsepower, reciprocating
Damage
Substantial damage
Flight
Public aircraft · Part 91
Registered owner
State of Alaska, Department of Public Safety
Airworthiness certificate
Standard, Normal
Last inspection
100 hour · September 27, 2000 · 77 hours before
Departed
Eureka, AK

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
47
Injuries
None
Certificates
Flight instructor, Commercial, Airline transport
Airplane ratings
Single-engine land, Single-engine sea, Multi-engine land
Instrument ratings
Airplane
Medical
Class 2, Valid Medical--w/ waivers/lim
Last flight review
April 20, 2000
Seat
Right
Flight hours
17,783 total · 221 in this make and model · 17,463 as pilot in command · 35 in the last 90 days · 9 in the last 30 days · 2 in the last 24 hours

Weather

Conditions
Visual (VMC) · Day
Wind
90° at 8 knots
Visibility
30 statute miles
Lowest ceiling
None
Temperature
10 °F

FAA reports on this event · 1

The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.