Accident Overview
On a visual flight rules (VFR) flight from Fort Frances to Granite Lake, a Rusty Myers Flying Service float-equipped Beech D18S, registration C-FBGO (serial No. CA-215), departed with one pilot and four passengers. About halfway to Granite Lake, just north of Ignace, the pilot encountered increasing rain and decreasing visibility. After several course deviations, the pilot could not find a route through the poor weather or a suitable lake for landing. While manoeuvring at low level with heavy rain obscuring the horizon, the pilot reported partial engine power loss due to carburettor icing. Carburettor heat was applied but did not restore power or sustain altitude. The aircraft descended into trees, travelled about 500 feet through them, and the left wing was torn off. A fuel-fed fire broke out almost immediately.
Occupants and Injuries
All five occupants survived the crash with minor injuries and exited the aircraft. The passenger in the co-pilot seat received burns to his upper body. The crash site was overflown about 15 minutes later by a second company pilot, who transmitted a Mayday. The occupants were picked up by helicopter about one hour later.
Flight Operations and Weather
The company operated float-equipped aircraft from Fort Frances, providing transportation to outpost camps in northwestern Ontario. Pre-flight and en route weather was predominantly acquired from other pilots and camp operators. At the time of the accident, the closest weather reporting station, Sioux Lookout (about 35 miles north), reported 300 feet overcast, visibility two miles in drizzle and fog, temperature and dew point 12.6 °C. The pilot had flown into heavy rain that obscured the horizon, confirmed by the co-pilot seat passenger.
Pilot and Second Aircraft
A second Rusty Myers Beech D18S departed Fort Frances on a similar route moments ahead of C-FBGO. The two pilots communicated weather and position reports. The second aircraft deviated around the marginal weather area that C-FBGO entered, and during the deviations, the relative positions changed. Just prior to the crash, the pilot of C-FBGO knew the second aircraft was ahead in better weather but was not fully aware of the change in relative positions. About 30 seconds after the last communication, C-FBGO descended into trees. The second pilot, unaware of the crash, later saw smoke from the crash site and called the Mayday.
Aircraft and Fuel
The aircraft was operated on a mixture of 25% 100 low-lead aviation gasoline and 75% automotive fuel (MOGAS). The Aeronautical Information Publication (AIP) carburettor icing chart indicates that at 12.6 °C temperature and dew point, serious carburettor icing can occur at any power setting. A note states that MOGAS is more susceptible to carburettor icing due to higher volatility.
Carburettor Icing
The company chief pilot recommended applying full carburettor heat before entering precipitation and leaving it on. The occurrence pilot used a different technique, applying heat only when entering precipitation or when ice occurred. The Airplane Flight Manual (for the Beech D18S) stated that heat should not be used unless the engine gets rough or manifold pressure drops. The RCAF Expeditor manual used by the company recommended using manifold heat continuously to prevent ice when icing conditions prevail.
Post-Crash Events
After the crash, the pilot attempted to grab the first aid kit but could not remove it quickly due to its mounting. The survival kit was stowed behind baggage, blocking access. The intensity of the fire prevented anyone from returning to retrieve it.
Investigation Findings
Investigators did not visit the site due to sufficient witness information and remoteness. Weather data from Sioux Lookout confirmed conditions. The pilot was certified and qualified. The investigation determined that while on a VFR flight, the pilot continued flight into adverse weather and lost all reference to the horizon. The pilot had exchanged weather information with another pilot and believed conditions would improve, deviated from company practice of staying on an over-water route or landing, and may have been at a lower altitude due to rain refraction on the windshield. The temperature and dew point were conducive to carburettor icing; the fuel mixture was more susceptible; the pilot's technique was not as recommended; and the engines lost partial power, likely due to carburettor ice.