Let's look at the facts of the Mt Gambier case. According to the ATSB report the pilot was fatigued. He flew from Port Augusta to Whyalla to Adelaide to Mt Gambier (ETA 2330L) and had never landed there at night before -and then planned to fly to Sydney. All single pilot. The patient (who was a small boy) was going to Sydney for a kidney transplant. He had been waiting for weeks and suddenly one became available -hence the call-out. As far as I know there was no special equipment aboard re extra weight.
That is one hell of a long flight for a single pilot operation. The T-VASIS at Gambier was known was to be dodgy in moisture laden air where dry bulb was close to wet bulb or dew point. That night it was drizzly, scattered at 800 ft, mist, dry bulb and dew point 11C and a well known black hole approach.
Mysteriously,six months after the accident ERSA was amended to caution pilots that the T-VASIS at Mount Gambier could give erroneous indications in certain atmospheric weather conditions. Quite a coincidence, don't you think?
That caution was not wrong. Reports from pilots familiar with Mt Gambier T-VASIS revealed that the indications were often very misleading with unreliable glide path signals. Air Services were not notified.
The ATSB for various reasons were never aware of this until after their report was published and new evidence came to light about the state of the VASIS. While a tired pilot may have been misled by erroneous T-VASIS indications that night, the presence of a second pilot monitoring would have increased the chances of a false glide slope be detected.
That mining corporations, state premiers and a lot of companies that charter aircraft for their employees insist on a two pilot operation is not because the charterers consider the skills of single pilots are inadequate. It is because the insurance companies and the charterers recognise that two pilot IFR operations are safer that single pilot operations. Few will argue against that fact. Even ATSB said that in their report on the Mt Gambier accident.
The ATSB report also stated that the extra cost of employing a second pilot is often the reason why some operators stick with a single pilot operation. The RFDS ask for tenders to operate aircraft on their behalf and rely heavily on donations from the public. It is less money paid out to operate single pilot, isn't it?
While the aircraft that the RFDS operate are certified to be operated by one pilot, the environment in which these pilots operate would strongly suggest it is safer to use two pilots.