ANC03LA007

NTSB accident investigation · Cessna 207 · Marshall, AK · October 29, 2002

Accident · Serious injuriesLimited investigationFinal report
Date
October 28, 2002, 20:00 local (Oct 29, 2002, 00:00 UTC)
Place
Marshall, AK
Injuries
1 serious
Damage
Substantial damage
Phase of flight
Enroute
Aircraft
N91090Cessna 207
Weather
Visual (VMC) · Night/dark
Status
Completed · report April 18, 2003
Report
Approved by Office Director
NTSB office
Alaska Regional Office
Parties
Anchorage FSDO-03
FAA report
20021028028979A
Case key
55976

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 failure to maintain clearance from terrain, which resulted in an in-flight collision with a ridgeline. Factors contributing to the accident were the high terrain, the pilot's inadequate preflight planning, and the dark night light 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/waterCruise
Light condition - dark nightFactor
Terrain condition - high terrainFactor
Clearance - not maintainedPilot in commandCause
Preflight planning/preparation - inadequatePilot in commandFactor

Analysis

The commercial pilot was positioning the airplane from the departure airport to another airport. The flight took place on a dark night with overcast skies, and no discernible horizon. The pilot departed and climbed to a cruise altitude between 1,200 and 1,400 feet msl. About 4 miles south of the departure airport, the airplane collided with an east-west ridge at 1,200 feet msl. The ridgeline is perpendicular to the direct route of flight between the departure and destination airports, and rises from west to east with a summit elevation of 1,714 feet msl. The departure airport was a newly commissioned airport 3 miles east-northeast of the old airport. The accident flight was the pilot's second trip to the new airport, and his first night departure from either the old or new airport. Direct flight from the new airport to the destination airport requires a higher altitude to clear the ridgeline than does a direct flight from the old airport. A direct flight from the old airport crosses the same ridgeline farther to the west, where the elevation of the ridge is less than 500 feet msl.

Factual narrative

On October 28, 2002, about 2000 Alaska standard time, a Cessna 207 airplane, N91090, sustained substantial damage when it collided with terrain during cruise flight, about four miles southeast of Marshall, Alaska. The airplane was being operated by Grant Aviation Inc., Anchorage, Alaska, as a visual flight rules (VFR) positioning flight under Title 14, CFR Part 91, at the time of the accident. The solo commercial pilot received serious injuries. Night visual meteorological conditions prevailed, and company flight following procedures were in effect. The flight originated at the Marshall Airport about 1955, and was bound for Bethel, Alaska.

The accident airplane departed the 'new' Marshall airport (MLL). The 'old' Marshall airport (MLL) was decommissioned several days earlier. The new airport is 3 miles east-northeast of the old airport, and was not yet depicted on current navigation charts, nor listed in the current United States Government Flight Information Publication, Alaska Supplement.

When the flight failed to arrive at Bethel, a search was initiated. On October 29, about 0100, search personnel located the wreckage about 4 miles southeast of Marshall. The airplane was located about 1,200 feet msl, on the north side of a ridgeline that runs generally east to west. The ridge has a summit elevation of 1,714 feet msl.

The airplane was equipped with Capstone navigation and terrain avoidance avionics. The Capstone equipment uses GPS mapping technology and aircraft position information, in conjunction with a multifunction display in the instrument panel, to graphically represent the aircraft's position relative to terrain. Terrain that comes within set parameters for altitude and horizontal distance is displayed in color bands. Terrain depicted within the red color band is intended to warn the pilot of the close proximity of terrain to the aircraft.

During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on November 4, the pilot said he departed Marshall on runway 07, and made a climbing right turn at 80 knots indicated airspeed toward Bethel. He said the vertical speed indicator read in excess of 1,000 feet per minute rate of climb, that it was a very dark night, and there were no visible horizon or ground references discernible. He said his route was direct to Bethel at 1,200 to 1,400 feet msl, and that upon reaching his cruise altitude, there was a strong headwind and turbulence. He said just prior to impacting the terrain, his vertical speed indicator showed a high rate of descent, and his Capstone display was almost completely red. He further stated the airplane's GPS had not been reprogrammed to reflect the location changes for the old Marshall airport and the new Marshall airport. The pilot said he had made one flight into the old Marshall airport, and this was his second flight into the new Marshall airport. This was the first flight when he departed either airport after dark. He said there were no preimpact mechanical anomalies with the airplane.

Direct flight from either Marshall airport to Bethel requires crossing an east-west ridgeline on the north side of the Yukon River. The direct route from the old Marshall airport to Bethel crosses the western foot of the ridgeline at a point with an elevation of less than 500 feet msl. The direct route from the new airport to Bethel crosses the ridge at a point where the elevation of the ridge exceeds 1,200 feet msl.

During a telephone conversation with the NTSB IIC on November 6, the pilot of the Army helicopter that located the accident airplane said their initial attempts to locate the missing airplane were futile. He said they then flew to the new Marshall airport and attempted to recreate the accident flight by taking off into the wind, conducting a right down wind departure replicating the performance of the Cessna 207, and heading direct to Bethel. He said when they reached the ridgeline on the north side of the Yukon River they headed east up the ridge toward the summit (1,704 msl). They located the accident airplane within minutes at 1,200 feet msl. He said the airplane impacted near the crest of the ridge, with a shallow angle of attack. He also stated that all the major airframe components sustained substantial damage, and the engine had separated from the airplane. The helicopter pilot said after they landed he noted that the wind was strong out of the northeast, with gusts above 40 knots. He said during the time they were searching for the accident airplane they did not encounter turbulence.

The weather forecast for the Yukon/Kuskokwim Delta area at the time of the accident was scattered clouds at 3,500 feet msl, occasional broken clouds at 3,500 to 6,000 feet msl, with an outlook for VFR and windy conditions. The freezing level was at 1,500 feet msl, and no turbulence was forecast.

During the accident sequence the emergency locator transmitter (ELT) did not activate. The injured pilot removed the ELT from its holder, and took it with him into the empennage where he sheltered himself from the weather. He was not aware the ELT was not transmitting. Rescue personnel recovered the pilot and the ELT. The ELT was released to the operator who proceeded to functionally test the ELT until it activated. It is unknown why the ELT did not operate upon impact.

Aircraft

Registration
N91090
Reported as
Cessna 207
Category
Airplane
Serial number
20700069
Airframe hours
14,551
Engine
Continental IO-520-F, 300 horsepower, reciprocating
Damage
Substantial damage
Flight
Positioning · Part 91
Registered owner
Grant Aviation Inc
Airworthiness certificate
Standard, Normal
Last inspection
100 hour · October 2, 2002 · 92.3 hours before
Departed
MLL · Marshall, AK
Destination
BET · Bethel, 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
30
Injuries
Serious
Certificates
Flight instructor, Commercial
Airplane ratings
Single-engine land, Multi-engine land
Instrument ratings
Airplane
Medical
Class 1, Valid Medical--w/ waivers/lim
Last flight review
October 5, 2002
Seat
Left
Flight hours
1,745 total · 115 in this make and model · 1,500 as pilot in command · 75 in the last 90 days · 56 in the last 30 days · 5 in the last 24 hours

Weather

Conditions
Visual (VMC) · Night/dark
Wind
40° at 15 knots, gusting 24
Visibility
10 statute miles
Lowest ceiling
None
Temperature
36 °F, dew point 30 °F
Altimeter
29.34 inHg

Docket · 1

The files NTSB released with the investigation on March 4, 2003, on NTSB’s docket system: statements, records, photos and specialists’ reports. 724 KB in all.

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 N91090 · 1

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