Four parachutists were forced to bail out of a light plane as it lost altitude in skies south of Adelaide earlier this year when the engine cut out mid-air, according to an Australian Transport Safety Bureau (ATSB) report.

Key points: The Cessna had reached a height of 8,000 feet when its engine cut out on February 3

The Cessna had reached a height of 8,000 feet when its engine cut out on February 3 It began descending and four parachutists were forced to jump out

It began descending and four parachutists were forced to jump out An ATSB probe found the pilot forgot to change fuel tanks

The incident, which happened on February 3, involved a single-engine Cessna 206 which had taken off from Aldinga — a popular departure point for skydivers because of its proximity to the McLaren Vale wine region.

The aircraft had reached an altitude of 8,000 feet when one of its tanks ran out of fuel about 1:45pm, causing the engine to fail.

An ATSB briefing described it as a "serious incident", noting the pilot forgot to switch fuel tanks and unsuccessfully "attempted to restart the engine".

The plane began descending and the parachutists bailed out at 6,500 feet.

The pilot then headed back to Aldinga, but was able to get the engine going again at 5,000 feet.

"After landing, the fuel tanks were dipped and it was found that the right tank was empty while the left tank had 110 litres of fuel on board," the ATSB's briefing stated.

"The pilot said that he likely forgot to change fuel tanks because he was distracted due to radio calls and high workload."

The ATSB said the incident served as a warning about the need for pilots to be vigilant about fuel systems.

"Accidents involving fuel mismanagement are an ongoing aviation safety concern," it said.

"In this instance, selecting the appropriate fuel tank during checks would have avoided the pilot having to manage fuel during a high-workload period."

Aldinga Airfield has been contacted for comment.