Casualties unknown

2021-05-14: Robinson R44 Raven II (ZS-RSK) — Vaal Marina Bay, Vaal Dam, Gauteng, ZA

Vaal Marina Bay, Vaal Dam, Gauteng, ZA

On May 14, 2021, a Robinson R44 Raven II (registration ZS-RSK) was involved in an aviation accident near Vaal Marina Bay, Vaal Dam, Gauteng, ZA. Investigators recorded the probable cause as: The glassy water illusion likely caused the pilot to misjudge the helicopter's height above the water, leading to an inadvertent descent and contact with the water surface. This summary draws on records from the South African Civil Aviation Authority (SACAA) Accident and Incident Investigations Division.

Sourcesthe South African Civil Aviation Authority (SACAA) Accident and Incident Investigations DivisionPrimary reportUpdated 1785104676Data APIEditorial standards

On 14 May 2021, a Robinson R44 Raven II (ZS-RSK) crashed into Vaal Marina Bay, fatally injuring the pilot and passenger. The investigation cited glassy water illusion as the likely cause, leading to the pilot misjudging height.

Accident Summary

On 14 May 2021, at approximately 1554Z, a Robinson R44 Raven II helicopter, registration ZS-RSK, sustained substantial damage during an accident at Vaal Marina Bay, Vaal Dam, Gauteng Province. The helicopter was operated privately under Part 91 of the South African Civil Aviation Regulations (2011). On board were a male pilot (age 59) and a female passenger, along with two dogs. The pilot held a valid Private Pilot Licence with approximately 909.7 total flying hours, including about 900 hours on type.

The flight departed Rand Airport (FAGM) at around 1530Z, intending to land on a strip near the pilot's residence at Burgundy Bay, Vaal Marina Bay. The approach was made in visual meteorological conditions initially, transitioning to night conditions. Approaching from the northwest at low altitude over the water, the helicopter turned to line up for a straight-in landing on an open grassy strip. A witness at the house reported receiving a call from the pilot about three minutes before final approach, requesting that a spotlight be activated to illuminate the landing area. The witness recorded video of the approach, which showed no anomalies in engine or helicopter operation. The water in the bay was calm and glassy, reflecting the surroundings.

In the video, the helicopter descended rapidly and flew very low toward the water while turning toward the landing site. It struck the water surface, producing a bright spark and loud bang, attributed to the main rotor severing the tail boom. The helicopter came to rest on its right side with the left skid above water before sinking. The bodies of the pilot and passenger were recovered that day; both were confirmed fatally injured by emergency services. The larger dog and the tail boom were recovered four days later. The helicopter was lifted using floating bags and transported to Wonderboom National Airport for examination.

Investigation Findings

The investigation analyzed witness video footage and determined that the helicopter flew over calm, glassy waters that mirrored the surroundings. This glassy water illusion likely caused the pilot to perceive a higher altitude than actual, leading to a reduction in height and subsequent water contact. The Robinson R44 Pilot Operating Handbook includes Safety Notice SN-19, which warns of depth perception loss when flying low over water, particularly glassy water, and advises maintaining at least 500 feet AGL and avoiding maneuvers below 200 feet AGL.

The accident helicopter was not equipped with emergency floatation devices (EFS), which might have reduced the risk of sinking. The report notes that EFS are designed to prevent helicopters from sinking or capsizing in water impacts.

Safety Recommendations

The investigation recommended that the Director of Civil Aviation mandate the fitment of emergency floatation devices on helicopters operating over water, including those that approach, land, or take off over large water masses. A safety message also encouraged helicopter owners in areas with large water bodies to consider installing such devices.

Probable cause

The glassy water illusion likely caused the pilot to misjudge the helicopter's height above the water, leading to an inadvertent descent and contact with the water surface.