Australia is continuing the process of tightening the rules governing helicopter flights in the wake of the fatal 18 August 2011 crash of a Eurocopter AS355F2 Twin Squirrel at Lake Eyre in South Australia.

The Australian Transport Safety Board report says the single pilot became disorientated when flying under night visual flight rules (VFR) on a completely dark night. The aircraft (VH-NTV) entered an unintended descent during a right turn, and eventually impacted the ground at high speed with 90deg bank. Neither the two passengers nor the pilot survived the crash.

The ATSB notes that a night flight when there is no celestial or terrain light is effectively in instrument meteorological conditions (IMC) and therefore it should be conducted under instrument flight rules (IFR).

It advises operators planning night VFR flights to assess the potential for encountering “dark night conditions”, concluding: “If there is a likelihood of dark night conditions, the flight should be conducted as an IFR operation, or conducted by a pilot who has an IFR-equivalent level of instrument flying proficiency and in an aircraft that is equipped to a standard similar to that required under IFR.”

As a result of ATSB recommendations, Australia's Civil Aviation Safety Authority (CASA) advises that it will require helicopter commercial air transport operations with passengers at night to be carried out either in a helicopter fitted with an autopilot or with a two-pilot crew.

The report says the helicopter took off from an island in the Coopers Creek inlet, South Australia, carrying a film crew for Australian broadcaster ABC on a planned 30min flight. The pilot leveled it at 1,500ft (460m) above sea level, shortly after which it entered a gentle right turn and began descending. The turn tightened and the descent rate increased, resulting in the helicopter hitting the ground at high speed with a bank angle of about 90deg around 38s after initiating the manoeuvre.

Witnesses who saw the helicopter depart said they noticed the helicopter descending and turning followed by "a fireball and orange glow". A fuel-fed fire consumed most of the aircraft's wreckage.

The ATSB determines that before departure, the pilot had "probably" selected an incorrect destination on the aircraft's global positioning system. After leveling and initiating the right turn, the pilot became spatially disorientated. Contributing factors were the "dark night" conditions, an attempt to correct the GPS input while leveling the aircraft for cruise flight, and the pilot’s limited recent night and instrument flying experience. The helicopter was not equipped with an autopilot, it adds.

ATSB notes that existing rules on night VFR operations do not take into account "dark night" conditions that are effectively the same as IMC, but without the same level of safety provided by IFR requirements.

New regulations being introduced either late this year or in early 2014 - which do not come into force until 2015 - will require all air transport flights in helicopters with passengers operating at night to be equipped with an autopilot or a two-pilot crew, says CASA. The agency had already been revising the rules governing pilot licencing - requiring a biennial examination of night-flight competence - prior to the August 2011 incident.

While this extends the range of operations required to have such risk controls, the ATSB notes it does not address the situation for other helicopter operations, namely those not carrying passengers. However, it says that CASA should "prioritise its efforts" to address the safety risk associated with non-air transport flights.