A pilot who dozed off during a flight from Devonport to King Island had not slept for 24-hours, an Australian Transport Safety Bureau investigation has found.
The pilot was conducting an early morning freight flight for Vortex Air on November 8 when he fell asleep and flew approximately 78 kilometres past King Island on autopilot.
The ATSB found the pilot had been unable to sleep during a scheduled rest period but even if he had, "he still would have been fatigued to a level known to affect performance".
The pilot eventually awoke and landed the Piper PA-31-350 on King Island without incident after several attempts at contact by Air Traffic Control and other pilots.
"However, after talking with the operator, the pilot then flew from King Island to Moorabbin to complete his shift," the ATSB report said.
ATSB executive director of transport safety Nat Nagy said the investigation highlighted "the need for pilots to assess their level of fatigue before and during their flight".
"Before commencing night operations pilots are encouraged to modify their usual sleep routines to ensure they are adequately rested," Mr Nagy said.
The ATSB has also called for operators to consider the risks of allowing pilots to continue flying directly after a fatigue-related incident without corrective management.
"Just as it is the pilot's responsibility to use rest periods to get adequate sleep and to remove themselves from duty if they feel fatigued, it is also incumbent on operators to implement policies and create an organisational culture where flight crew can report fatigue and remove themselves from duty in a supportive environment," Mr Nagy said.
Vortex Air last year said the company had adhered to all safety procedures and regulatory compliance requirements.
"The flight was the pilot's first roster flight with the company after returning from a period of leave, and they had declared themselves fit to fly," the company said in a statement.
"The pilot was adequately experienced and had previously flown the route a number of times without incident."
Vortex Air has been contacted for comment.