Accident Sequence
At approximately 1930 eastern standard time, a student and instructor pilot were conducting night visual approaches at Centralia/Huron Airpark, approximately 22 nautical miles northwest of London, Ontario. The student, occupying the left seat, was practicing on his second night flight. During the third or fourth circuit to runway 10, the aircraft struck a tree approximately 40 feet high and 3,000 feet short of the runway threshold. Following the tree strike, the aircraft impacted the ground in a steep, nose-down attitude and came to rest inverted. The instructor, who sustained minor injuries, extricated himself and walked three kilometres to call for assistance. The student, seriously injured, remained in the wreckage until rescued by local authorities. The emergency locator transmitter activated but was not needed for location.
Aircraft and Aerodrome
Records indicate the aircraft was certified and maintained per regulations; no pre-occurrence discrepancies were found. Centralia/Huron Airpark is a certified aerodrome with a 5,012-foot by 100-foot asphalt runway (runway 10). Medium intensity runway edge lights (three settings), threshold lights, and end lights were available and serviceable, but no approach lighting or glide path indicator systems existed. The aerodrome uses an ARCAL system on 122.8 MHz. The surrounding terrain is level farmland at about 825 feet above sea level, with limited visual references at night, notably the runway lights and the small town of Crediton, which provided no glide path information.
Pilot Information
The student held a valid private pilot licence. His logbook showed no flying from August 1979 to May 1995, then 18.3 hours accumulated by February 1996, including 6.3 hours of instrument training and 5.0 hours of simulated instrument time. His first night training flight (1.1 hours at London) occurred on 30 January 1996. Prior to the accident, he had not conducted a night circuit without visual approach slope indicators, which were available at London. The instructor held a valid commercial licence and was qualified for the flight; he had flown about 6.8 hours with the student, including the student's first night flight.
Environmental Factors
Initially, weather was clear with unlimited visibility and light, variable winds. During the flight, a high broken to overcast cloud layer formed, partially concealing the moon and reducing ambient light. The altimeter setting was 29.98 inches of mercury, correctly set. The landing environment lacked ambient visual cues, conditions described in Transport Canada's Instrument Flight Procedures Manual as conducive to the "black-hole illusion," where pilots overestimate altitude and descend prematurely. Research by Drs. Kraft and Elworth (1968) demonstrated that even experienced pilots can fly too low under such conditions if they do not cross-check the altimeter.
Findings and Cause
The aircraft struck the tree while well below the correct final approach path in controlled flight. Neither the instructor nor the student monitored the aircraft's altitude during the approach. The ambient conditions and landing environment were conducive to black-hole illusion, which likely influenced their perception. Additionally, the runway width (100 feet) was narrower than the student's previous practice runway (200 feet), and no glide path aids were present.