What happened
On 04 August 2006, a mid-air collision occurred approximately 1 nm west of Caledon, Ontario, involving two light aircraft operating under visual flight rules in Class E airspace. The first aircraft, a Cessna 172P with registration C-GFGD, was being operated by the Brampton Flying Club for a student pilot's instructional flight. The second aircraft, a C-GCHN Cessna 182T, was being flown by its owner on a flight from Burlington Airpark to Parry Sound.
At approximately 1234 EDT, the C-GFGD was descending from 3800 feet toward 2400 feet on a southeasterly track. Simultaneously, the C-GCHN was maintaining a steady altitude of 2400 feet on a northbound path. The two aircraft converged at a 120° angle with a closure rate of roughly 200 knots. During the impact, the right wing of the C-GCHN was torn away, causing it to become uncontrollable. The C-GFGD sustained damage to its cockpit and nose area. Both aircraft crashed near the collision site, resulting in 3 fatalities. A small post-impact fire occurred after debris severed a power line, but no fire was found in the primary wreckage.
The investigation
Investigators examined the wreckage and radar data, finding that neither aircraft had performed evasive maneuvers before the collision. The aircraft struck each other while both were in wings-level flight. Maintenance records for both planes were found to be in compliance with regulations, and there was no evidence of mechanical failure or pilot impairment prior to the event.
The investigation also looked into the airspace structure. The accident occurred in an area where traffic is vertically concentrated at 2400 feet because the floor of the adjacent Class C airspace is 2500 feet. While the C-GCHN was equipped with a traffic information service (TIS), this service was unavailable in Canada. Neither aircraft was equipped with a traffic alert and collision-avoidance system (TCAS).
Findings
- The collision was caused by the failure of the see-and-avoid principle to prevent the impact.
- The aircraft were on a constant collision course, meaning there was no relative angular movement to alert the pilots via peripheral vision.
- The probability of either crew detecting the other was estimated at only 2/5.
- High traffic density and the vertical compression of flight levels in the area increased the risk of conflict.
- The lack of automated traffic alerting technology for VFR aircraft in this airspace left pilots solely dependent on visual scanning.