History of Flight
On November 18, 2011, at about 1350 mountain standard time, a Cessna 337G (registration N357) was substantially damaged after impacting terrain during a missed approach at Casper/Natrona County International Airport (CPR), Casper, Wyoming. The private pilot, the sole occupant, was fatally injured. Instrument meteorological conditions prevailed for the personal cross-country flight, conducted under 14 CFR Part 91 with an instrument flight rules flight plan. The flight departed Rawlins Municipal/Harvey Field Airport at about 1315, with CPR as its destination.
Radar and voice data from the Federal Aviation Administration showed that while tracking the ILS localizer to runway 03, the pilot was observed about one-quarter mile right of track. The tower controller informed the pilot and requested verification of alignment. The pilot responded, “Yeah. We’re having a little rodeo up here.” At 1340:11, the controller instructed the pilot to fly runway heading (030 degrees) and climb to 8,000 feet for radar vectors. The pilot acknowledged. At 1340:28, the approach controller instructed a climb to 8,600 feet, which the pilot confirmed. At 1341:47, the controller asked for the tower-assigned heading; the pilot requested it again, and the controller repeated “fly heading zero three zero.” The pilot read back correctly. At 1343:27, the controller advised that the runway visual range (RVR) was 2,000 feet, below ILS minimums, and offered holding or vectoring for another approach; the pilot chose vectoring. The controller issued headings of 310, 270, and 220 degrees. At 1347:26, the pilot reported radio squealing and asked for a repeat. The controller reiterated the heading and noted RVR increasing. At 1348:05, the controller advised the pilot was tracking about 130 degrees and instructed a downwind heading of 250 degrees. At 1348:35, the controller issued a low altitude alert, advising minimum vectoring altitude of 7,500 feet, and instructed a climb to 8,600 feet, asking if the pilot was having trouble maintaining altitude. No further transmissions were received. Radar contact was lost about one minute later.
The airplane was located about 8 miles northeast of CPR in a snow-covered area of gently rolling terrain with sparse vegetation. The wreckage came to rest upright in a tightly confined area. All major components were accounted for, and the airplane was consumed by postcrash fire. A Federal Aviation Administration safety inspector noted that due to thermal distress, no evidence of ice accumulation was found on any part of the airplane.
Pilot Information
The pilot, aged 61, held a private pilot certificate with airplane single-engine land, multiengine land, and instrument airplane ratings. His most recent logbook entry, dated February 18, 2011, showed total time of 4,582 hours, with 4,487.8 hours as pilot-in-command. He logged 702 hours of multiengine time, 3,843 hours of single-engine time, and 687.3 hours in the accident make and model. He recorded 644.7 hours of actual instrument time and 648.9 hours of night time. His most recent instrument approaches (10) were completed in a simulator on February 15, 2011, during training at Recurrent Training Center. After that training, he logged a 4.9-hour cross-country IFR flight with 1.0 hour of actual instrument time but no instrument approaches. No other instrument flight time or approaches were logged from February 18, 2011, up to the accident date, about nine months later.
Additional documentation provided by the co-owner indicated that from March through October 2011, the pilot accumulated 40.3 hours in the accident airplane, with no breakdown of instrument or visual conditions. He flew about 12 hours in the last 90 days, 1.2 hours in the last 60 days, and no flight time in the 30 days preceding the accident. The pilot's most recent third-class medical certificate was issued on May 6, 2011, with the limitation “must wear corrective lenses.”
Aircraft Information
The pressurized, in-line thrust Cessna 337G was manufactured in 1976 and operated with a standard airworthiness certificate in the normal category. It was powered by two Continental TSIO-360-series engines, each rated at 225 horsepower, driving McCauley two-bladed constant-speed propellers. The airplane was on an annual inspection program; the last inspection was performed on April 5, 2011, at a total airframe time of 3,187.1 hours. Maintenance records showed that the rear engine (serial number 1000310) and front engine (serial number 824819-R) had accumulated 473.3 hours since their last overhaul as of September 30, 2011.
The airplane was equipped with navigation and flight instruments suitable for instrument meteorological conditions. On February 12, 2012 (note: likely a typo in source; date after accident, but source states this), an ASPEN Electronic Flight Display 1000PRO was installed, featuring an autopilot, flight director, altitude alerter, slaved directional gyro with heading bug, and other advanced functions. It also had Cessna’s “Known Icing Conditions” deice system kit, including electric deicing pilot’s windshield panel, wing and empennage deice boots, heated pitot head and static ports, and propeller deice boots.
A review of maintenance records showed that on February 10, 2011, the airplane was inspected in accordance with 14 CFR Part 91.411 for altimeter system and altitude reporting equipment tests.
Meteorological Information
The pilot obtained an outlook briefing and filed an IFR flight plan on November 17, 2011, followed by an abbreviated briefing at about 1200 MST on November 18. In both briefings, the AFSS briefer indicated snow showers were expected over most of Wyoming. The 1200 MST briefing noted AIRMETs for IFR and mountain obscuration, moderate icing, moderate turbulence, and low-level wind shear. The freezing level was at the surface, with multiple cloud layers implying existing icing conditions.
At 1335, about five minutes before the accident, a special weather observation at CPR reported wind 360 degrees at 8 knots, visibility 1 ¾ miles in light snow and mist, scattered clouds at 800 and 1,200 feet, overcast at 2,500 feet, temperature -1°C, dew point -3°C, altimeter 29.56 inches Hg. At 1348, about eight minutes after the accident, conditions deteriorated to visibility ½ mile in moderate snow and freezing fog, overcast at 1,300 feet, temperature -2°C, altimeter 29.55 inches Hg.
Earlier that morning, snow was reported between 0740 and 0804, and resumed before the accident at 1247, with conditions rapidly becoming IFR with wet snow, mist, and freezing fog, ending at 0036 on November 19. The Terminal Aerodrome Forecast for CPR issued at 1031 MST expected better conditions initially, with the threat of wind shear, but with visibility greater than 6 miles until 1400 MST. The area forecast for Wyoming east of the continental divide predicted a broken layer at 8,000 feet, visibility 5 miles in scattered light snow showers, becoming overcast at 7,000 feet with visibility 3 miles in light snow. The outlook from 1700 to 2300 MST was for MVFR due to low ceilings and visibility in snow.
The National Weather Service had AIRMET Sierra for IFR conditions and mountain obscuration, AIRMET Tango for moderate turbulence and low-level wind shear, and AIRMET Zulu for moderate icing below 20,000 feet. The Weather Depiction Chart at 1200 MST showed IFR conditions over western and central Wyoming. Satellite imagery at 1345 MST indicated overcast nimbostratus clouds consistent with snow showers over the accident site.
A National Transportation Safety Board meteorologist provided Current Icing Potential products. A cross section for the route at 1300 MST indicated a deep layer of potential moderate icing between 6,000 and 19,000 feet over Casper, with 60-80% probability. Icing probability at the cruising level of 13,000 feet was greater than 50%, with areas of 70% or more near Casper. The icing severity chart showed a large area of moderate icing with scattered heavy or severe icing. Another chart continued to depict moderate to heavy icing over the region at the time of the accident.
Wreckage and Impact
The airplane came to rest on a measured magnetic heading of 355 degrees in a snow-covered field at coordinates 41°01.400'N, 106°21.134'W. The impact heading was consistent with the resting heading. The impact angle was estimated at about 30 degrees nose down in a left turn. The wreckage was confined to an area about 60 feet in diameter.
Flight control continuity was established from the bellcranks to the center cabin, except one rudder cable separated with an overload signature. Control continuity was also established from pilot controls to the center section. Fire and crushing damage prevented evaluation of cables below the cabin floor. The left wing was crushed aft with severe deformation and thermal distress; left flap and aileron remained attached. The left fuel tank was breached and thermally damaged. The right wing was destroyed by fire and impact; its flap, aileron, and fuel tank were destroyed. Both rudders remained attached to their vertical stabilizers with moderate sooting. The elevator was intact with moderate sooting; the elevator trim tab was measured at 10 degrees tab up, and its control cables had overload separation. The left and right main landing gear were down, with the right down lock broken. The nose gear was down.
On January 4, 2012, the engines were examined at a secured salvage facility. The front engine showed impact forces and thermal distress; continuity could not be confirmed. Both magnetos could not be rotated. Spark plugs had normal signatures. The fuel pump could not be rotated; the fuel manifold valve screen was clear. The mixture control was near full rich and movable; throttle moved freely. The oil sump had impact damage; oil screen was clear. Cylinders showed combustion deposits. The crankshaft flange separated from the crankshaft and remained attached to the propeller; the exposed crankshaft had spiral cracking. The crankshaft could not be rotated. Accessory gears were intact. The turbocharger drive shaft could not be rotated; blades and impeller intact. A portion of the vacuum pump drive coupling was missing; the pump rotor and vanes were damaged. The propeller governor control arm was in mid-travel; governor drive gear intact. The propeller separated from the engine; both blades had multidirectional scratches, and one had twisting damage. No anomalies were found that would have prevented the engine from producing rated horsepower.
The rear engine also showed impact and thermal distress. Continuity could not be confirmed. Magneto drive shafts intact but not rotatable. Spark plugs normal. Fuel pump not rotatable; manifold valve screen clear. Mixture near full rich; throttle free. Oil sump impacted; screen clear. Cylinders had combustion deposits. Propeller remained attached; crankshaft not rotatable. Accessory gears intact. Turbocharger drive shaft not rotatable; blades and impeller intact. Vacuum pump drive coupling partially missing; pump rotor and vanes damaged. Propeller governor control arm in mid-travel; governor drive gear intact. One propeller blade had a separated portion about mid-span; another had a bend toward the non-cambered side beginning about mid-span. No anomalies were found that would have prevented rated horsepower production.
Medical and Pathological Information
An autopsy performed on November 22, 2011, at McKee Medical Center in Loveland, Colorado, determined the cause of death as “multiple blunt force injuries.” The FAA's Civil Aeromedical Institute conducted toxicology tests; no ethanol was detected in liver or kidney, and drug tests were negative. No tests were performed for carbon monoxide or cyanide.