New safety measures proposed after Vaal Dam helicopter crash

A loss of depth perception could have caused the helicopter crash into the Vaal Dam last month in which Johannesburg businessman Essie Esterhuysen and his sister Dané died.

This finding is contained in the preliminary report by the South African Civil Aviation Authority (SACAA) after investigating the accident.

The accident occurred on May 14. Instead of landing on the grass strip next to the Esterhuysen’s Vaal Marina home, the helicopter plummeted into the water as family friends – who were making a video of the landing – watched in horror.

Esterhuysen’s two beagles also died in the accident.

The preliminary report contains a possible cause of the accident. It states: “Based on the video footage, the helicopter flew over calm, glassy waters that mirrored the surroundings. The glassy waters illusion could have given the pilot the perception that they were higher than they actually were, causing the pilot to reduce the height, resulting in the helicopter touching the water. This is known as a loss of depth perception while flying over calm, glassy waters.”

The report details the moments before the crash. The helicopter took off from Rand Airport at approximately 15:30 in ‘visual meteorological conditions’ – which means the pilot could fly according to his visual ability rather than relying solely on instrumentation. It approached the intended landing destination at dusk.

“The helicopter approached from the north-westerly direction and was flying at a low height above water before making a turn (over the water) to line up for a straight-in approach for landing on an open grassy strip between the dam and the houses,” states the report.

It describes how video footage of the accident shows how the helicopter approached in a normal flight path as the pilot had done in the past when about to land on the site.

“The helicopter is then observed descending rapidly and very low towards the water surface, while turning towards the landing site. It then struck the water surface, followed by a bright spark and a loud bang.”

The loud bang was attributed to the main rotor severing the tail boom section, which separated from the helicopter about a second before sinking.

The bodies of the Esterhuysens were recovered on the day of the accident.

“The body of the passenger was recovered by one of the fishermen who were camping on the west-side of the bay, about 150m from where the helicopter was observed floating a few minutes after the accident before it sunk under water. The pilot’s body was recovered later by the South African Police Service (SAPS) Diving Unit at a depth of 9.13m. Both occupants were confirmed fatally injured on site by emergency service personnel,” states the report.

One of the dogs was found in the helicopter, while the second dog, the pilot’s cellular phone and the tail boom and tail rotor drive shaft, were recovered on Wednesday, May 19 (five days after the accident).

The report says there were no ‘significant weather conditions in the area that would have contributed to the accident’, and no mechanical problems were identified. The pilot was licensed and qualified for the flight.

The accident was considered not survivable as the helicopter was submerged in water.

As a result of its investigations, SACAA is now recommending that all helicopters being operated over a large mass of water should be fitted with emergency flotation devices.

This finding is supported by an extract from the Robinson R44 II Pilot’s Operating Handbook (section 10).

“Many helicopter accidents have occurred while manoeuvring low over water. Many pilots do not realise their loss of depth perception when flying over water. Flying over calm, glassy water is particularly dangerous, but even choppy water, with its constantly varying surface, interferes with normal depth perception and may cause the pilot to misjudge his height above the water,” states the handbook.

Further investigations are being conducted to probe other aspects of the accident, which may or may not have further safety implications.

WARNING: Graphic footage shows moment helicopter crashes into Vaal Dam