What happened
On May 8, 2013, at approximately 16:58 UTC, a two-seat Rans Coyote II ES ultralight aircraft, registration OH-U2 and 275, was performing a landing on Lake Vähä-Löytäne in Orivesi, Finland. The aircraft, equipped with floats, was on its second flight of the day.
As the pilot approached the landing site from the north, the sun was positioned directly in the flight path. Due to the calm, windless conditions, a "sun bridge" effect occurred on the mirror-like water surface, which obscured the pilot's visual perception of the water's surface. While attempting to verify altitude by looking toward the shoreline, the aircraft struck the water with a descent rate higher than normal.
The impact significantly reduced the aircraft's speed. Although the pilot applied full power in an attempt to regain control, the aircraft struck the water a second time, causing it to capsize. The cockpit quickly filled with water, leaving the aircraft floating upside down. The pilot managed to release their seatbelt and escape, but the passenger, who likely sustained a head injury during the capsize, succumbed to the accident. The pilot's rescue efforts were complicated by the fact that their automatic life vest had inflated, making movement underwater difficult.
The investigation
The investigation examined the flight conditions, the aircraft's weight and configuration, and the pilot's approach. It was noted that the aircraft's mass at the time of the accident was approximately 505 kg, which exceeded its maximum allowable takeoff mass of 495 kg. The investigation also looked into the visibility issues caused by the sun's position and the impact of the automatic life vests on the rescue operation.
Findings
- The immediate cause of the accident was the aircraft striking the water with an excessive descent rate.
- The sun's position directly ahead of the landing path, combined with the calm water, created a visual illusion that led the pilot to misjudge the aircraft's altitude.
- The aircraft was likely overweight at the time of the accident.
- Inadequate preparation for a challenging landing contributed to the outcome.
- The inflation of automatic life vests hindered the pilot's ability to perform rescue operations while submerged.