Victorian couple Bev and Terry Fisher were killed when the aircraft they were in crashed to the ground just short of the runway at Mudgee Airport on the morning of September 14, 2014.

The pair had taken off from Dubbo Airport about 25 minutes earlier on board an amateur-built Van's Aircraft RV-6 two-seater. The pilot, Terry Fisher, had 40 years' flying experience.

The couple's plane was among a group of four that took off from Dubbo that morning. The other three aircraft landed safely.

In its report on the fatal crash, the Australian Transport Safety Bureau (ATSB) found the steep turn onto the final approach at low airspeed probably resulted in an accelerated aerodynamic stall shortly after the loss of engine power from which the pilot was unable to recover.

The aircraft hit the ground about 300m south west of the runway about 10.53am.

The ATSB also found the engine failure was probably due to carburettor icing, where ice continues to accumulate within the carburettor and airflow to the engine is reduced, stopping the engine if left unchecked.

The report said "environmental conditions at the time of the accident were conducive to serious carburettor icing at descent power, and the pilot-operated carburettor heat control was found in the OFF position".

There were other factors that increased risk, the report said, including the aircraft not being fitted with a stall warning device or angle-of-attack indicator, which increased the risk of a stall.

The plane was not required to be, and was not fitted with either device, however the report recommended owner-pilots of amateur-built planes operated in the experimental category, such as the aircraft in question, "should consider the benefits of such devices as a last line of defence against the inadvertent approach to, or entry into an aerodynamic stall".

The report also recommended pilots of aircraft fitted with a carburettor "check the forecast weather conditions and consider the risk of carburettor icing as a result of those conditions" before flying.