Sunday, April 21, 2019

Low Altitude Operation / Event: Cessna 182, XB-YUH; accident occurred August 16, 2015 in Big Piney, Sublette County, Wyoming

The National Transportation Safety Board did not travel to the scene of this accident.

Additional Participating Entity: 
Federal Aviation Administration / Flight Standards District Office; Casper, Wyoming

Aviation Accident Final Report - National Transportation Safety Board: https://app.ntsb.gov/pdf

Investigation Docket - National Transportation Safety Board: https://dms.ntsb.gov/pubdms

Location: Big Piney, WY
Accident Number: CEN15LA403
Date & Time: 08/16/2015, 1030 MDT
Registration: XBYUH
Aircraft: CESSNA 182
Aircraft Damage: Substantial
Defining Event: Controlled flight into terr/obj (CFIT)
Injuries: 2 Minor
Flight Conducted Under: Part 91: General Aviation - Personal 

Analysis 

The private pilot reported that, during a preflight briefing, he and the pilot-rated passenger (who was the owner of the airplane) agreed that in the case of an emergency, the owner would take control of the airplane. After takeoff, the sightseeing flight was normal until the airplane approached a glacier at 12,000 ft mean sea level. The pilot stated that because the airplane engine was normally aspirated, there was not much power left to climb, but everything was "ok." As the airplane entered the glacier area through a canyon, it encountered a sudden downdraft and started to descend; the pilot recalled that the airplane's altitude above terrain was about 500 ft. The pilot tried to maintain a level attitude, but the airspeed began to decrease as the airplane continued to descend. The pilot-rated passenger then took control of the airplane and immediately lowered the nose to increase airspeed and set up for an emergency landing; the airplane appeared to be stalling. The airplane landed hard on ice ditches, separating the nose gear. The main landing gear dug in and the airplane came to a stop, which resulted in structural damage to the fuselage. No mechanical malfunctions or failures were reported by the pilot. Because the engine was normally aspirated, the performance of the engine was reduced at a high altitude. Further, the airplane was about 500 ft above terrain when the downdraft occurred. Considering that downdrafts in high mountainous terrain can exceed 1,000 ft per minute, the pilot did not maintain adequate altitude for the operating environment.

Probable Cause and Findings

The National Transportation Safety Board determines the probable cause(s) of this accident to be: 
The pilot's failure to maintain adequate altitude while operating over high mountainous terrain, which resulted in an emergency landing after the airplane's encounter with a downdraft.

Findings

Aircraft
Altitude - Not attained/maintained (Cause)

Personnel issues
Use of equip/info - Pilot (Cause)

Environmental issues
Terrain - Contributed to outcome (Cause)

Terrain induced turbulence - Contributed to outcome (Cause)

On August 16, 2015 about 0930 mountain daylight time, a Cessna 182, XBYUH (Mexican Registry), impacted high mountainous terrain during a forced landing about 37 miles out from the Big Piney, Wyoming VOR (BPI) 015 Degree Radial. Both occupants, the pilot and pilot-rated passenger, sustained minor injuries. The flight was being conducted under the provisions of Federal Code of Regulations Part 91. Visual meteorological conditions prevailed throughout the vicinity and a flight plan was not filed. The local flight originated from the Alpine Municipal Airport (46U) about 0800.

The pilot reported that the purpose of the flight was sightseeing. During a preflight briefing, the pilot-rated passenger (who was the owner of the airplane), and the pilot agreed that in the case of an emergency, the owner would take control of the airplane. After takeoff from 46U, the flight was normal until approaching a glacier at 12,000 feet MSL. The pilot stated that because the airplane engine was normally aspirated, there was not much power left to climb, but everything was "OK." As the airplane entered the glacier through a canyon, a sudden downdraft caught the airplane and the airplane started to descend. The pilot recalls that the altitude above terrain was about 500 feet.

The pilot tried to maintain a level attitude and the airspeed began to decrease as the airplane continued to descend. The owner then took control of the airplane. He immediately lowered the nose to increase airspeed. Since the airplane was still descending, he asked for flaps and announced that he would execute an emergency landing. The airplane appeared to be stalling. The airplane landed hard on ice ditches, ripping off the nose gear. The main landing gear dug-in and the airplane came to a stop.


Figure 1. Approximate flight path into the glacier forced landing area. 

An American Airlines commercial flight picked up a mayday call and relayed the information to Salt Lake City Air Traffic Control. The wreckage was located by mountain rescue personnel and the two occupants were transported to a local hospital.

No mechanical anomalies were reported by the pilot or owner. According to the FAA, downdrafts in high mountainous terrain can exceed 1,000 feet per minute and a normally aspirated engine's horsepower and performance is reduced at high altitudes. 

Pilot Information

Certificate: Private
Age: 58, Male
Airplane Rating(s): Single-engine Land
Seat Occupied:Left 
Other Aircraft Rating(s): None
Restraint Used: 4-point
Instrument Rating(s): Airplane
Second Pilot Present: No
Instructor Rating(s): None
Toxicology Performed: No
Medical Certification: Class 3 Without Waivers/Limitations
Last FAA Medical Exam: 05/14/2015
Occupational Pilot: No
Last Flight Review or Equivalent:
Flight Time:  1904 hours (Total, all aircraft), 454 hours (Total, this make and model), 25 hours (Last 30 days, all aircraft), 2 hours (Last 24 hours, all aircraft) 

Aircraft and Owner/Operator Information

Aircraft Make: CESSNA 
Registration: XBYUH
Model/Series: 182 P
Aircraft Category: Airplane
Year of Manufacture:
Amateur Built: No
Airworthiness Certificate: Normal
Serial Number: 182633285
Landing Gear Type: Tricycle
Seats: 4
Date/Type of Last Inspection: 08/11/2015, Annual
Certified Max Gross Wt.: 2950 lbs
Time Since Last Inspection:
Engines: 1 Reciprocating
Airframe Total Time: 3093 Hours as of last inspection
Engine Manufacturer: Continental
ELT: C91  installed, activated, aided in locating accident
Engine Model/Series: O-470R
Registered Owner: On file
Rated Power: 230 hp
Operator: On file
Operating Certificate(s) Held: None

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation: 46U
Distance from Accident Site:
Observation Time: 0930 MDT
Direction from Accident Site:
Lowest Cloud Condition: Clear
Visibility:  10 Miles
Lowest Ceiling: None
Visibility (RVR):
Wind Speed/Gusts: 14 knots / 25 knots
Turbulence Type Forecast/Actual: /
Wind Direction: 260°
Turbulence Severity Forecast/Actual: /
Altimeter Setting: 30.31 inches Hg
Temperature/Dew Point: 16°C / 10°C
Precipitation and Obscuration:
Departure Point: Alpine, CO (46U)
Type of Flight Plan Filed: None
Destination: Alpine, CO (46U)
Type of Clearance: None
Departure Time: 0900 MDT
Type of Airspace:

Wreckage and Impact Information

Crew Injuries: 1 Minor
Aircraft Damage: Substantial
Passenger Injuries: 1 Minor
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 2 Minor
Latitude, Longitude:  43.159722, -109.658889

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