A pilot who fell asleep and overflew his Tasmanian destination had not slept for 24 hours before the incident, a safety report has found.

Key points: A Vortex Air pilot fell asleep while flying to King Island in November 2018 and flew 78 kilometres past his destination before waking

A Vortex Air pilot fell asleep while flying to King Island in November 2018 and flew 78 kilometres past his destination before waking The ATSB found the pilot had not slept for 24 hours before the flight and his fatigue was at dangerous levels

The ATSB found the pilot had not slept for 24 hours before the flight and his fatigue was at dangerous levels Vortex Air said the pilot deemed himself fit to continue flying on the day, adding he had been "counselled" and "continues to work with us"

The Australian Transport Safety Bureau (ATSB) report found the unidentified pilot, who was the only person aboard the Vortex Air freight flight on November 8, 2018, departed from Devonport for a 6:20am scheduled flight to King Island, reaching an "altitude of 6,000 feet".

"The autopilot maintained the aircraft's track and altitude, while the pilot listened to music through the radio and continued to monitor the flight," the ATSB noted.

As the aircraft neared the start of the descent into King Island, the pilot "started to feel tired and rapidly fell asleep", the report found.

Air Traffic Control (ATC) and other nearby pilots tried unsuccessfully to contact the Piper PA-31-350 registered as VH-TWU, and when the pilot woke up he discovered his autopilot had taken the aircraft 78 kilometres north of his intended destination.

He landed at King Island without injury or damage to the aircraft.

The ATSB reported the pilot "contacted his supervisor and ATC Melbourne Centre via telephone to discuss what had happened … the pilot then completed the shift, flying from King Island back to Moorabbin".

Vortex Air plane on tarmac. ( Instagram: Vortex Air )

The investigation found the pilot had been awake for about 24 hours before the incident and had not been able to sleep during a scheduled three-hour rest period before the flight.

Its report stated his level of fatigue would have affected his performance, even if he had been able to sleep during the rest period.

The report said the pilot also had not changed his sleep pattern in the week before the scheduled night flight, exacerbating his tiredness.

Safety warning on pilot fatigue

The ATSB investigation found the rosters given to pilots by Vortex Air often had no consistent pattern from week to week and usually included two to three night shifts, and were sometimes given to pilots at late notice.

The ATSB said this made it hard for pilots to plan their sleep patterns before flights.

"While this was not a factor in this occurrence due to the pilot knowing about the night shift in advance, it is important that rosters are maintained in a way that provide pilots the best opportunity to plan and obtain sleep to avoid flying while fatigued," the report stated.

It also found Vortex Air did put in place measures to ensure the pilot was fit to continue his shift before he flew from King Island to Moorabbin, despite knowing he had fallen asleep during the previous flight.

View from cockpit of Vortex Air aircraft. ( Instagram: Vortex Air )

The ATSB's executive director of transport safety, Nat Nagy, said the investigation showed the importance of pilots checking their level of fatigue before and during flights.

"Before commencing night operations pilots are encouraged to modify their usual sleep routines to ensure they are adequately rested," he said.

Mr Nagy said airline operators should also consider the dangers of allowing pilots to keep flying straight after a fatigue-related incident without taking steps to allow them to rest.

"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," he said.

Pilot made call on fitness to fly, Vortex says

Vortex Air managing director Colin Tucker said the pilot had made his own decision to fly back to Moorabbin without additional rest.

"We discussed the incident with the pilot at the time and he was deemed fit to fly."

Mr Tucker said the airline "counselled the pilot on the ground and when he returned to Moorabbin and he continues to work with us".

He said as a charter company, sometimes last minute flight schedule changes were unavoidable, but the pilot involved in the incident had not flown for five days prior, giving him plenty of time to rest.

Mr Tucker said Vortex Air was a small family charter company that had been servicing Tasmania for 30 years under challenging conditions for small operators.

In December 2018, the Australian Federation of Air Pilots (AFAP) revealed allegations some Vortex Air pilots were being paid less than the award rate. On Tuesday, when invited to comment, Vortex Air declined to make a statement on pilots' pay.

In March 2017, a Piper PA-31-350 being flown by a Vortex Air pilot clipped a truck as it was landing at Barwon Heads, near Geelong in Victoria.

The ATSB found the pilot came in too low over Barwon Heads Road, and the landing gear hit the truck.

In its report, the ATSB said it was told the pilot had recently taken on extra duties as the company's maintenance controller and was distracted during the landing by the additional pressures.