so, another classic knocked?
Not really. I just think that as usual all we have to go on is the witness report, and in this case we don't even have the witness.
Edit to add a bit more detail to explain this answer: I think really we need to weigh up the evidence in favour of the three main 'hypothesis'. Disregarding the arguments against, there's something
in favour of all of them, ie.
1. Valentich was in some way interacting with a UAP, advanced (earthly) weapons test, etc:
- The 'witness' statement talking about a craft of some sort
- The one, relatively weak, account of 'Ken Hansen', who claimed to have seen a light plane and UAP together
- A handful of other, weaker accounts of various UAPs around the time
2. Valentich became disorientated, perhaps while distracted by some mundane lights, and crashed:
- The twilight conditions meant the horizon between sea and sky would have been difficult to make out; while he had a fair number of hours, had flown at night and had done the King Island trip before, he'd not done it at night
- Venus was very bright and there were other lights (a lighthouse; fishing boats) or astronomical objects that could be misperceived
- The engine trouble might suggest he was not flying in a normal attitude
- Valentich might have had some interest in UFOs, though there's disagreement as to how deep his interest actually was, perhaps encouraging misperception
- A previous pilot of the aircraft had described it as "rough", saying that a thin film of oil that sprayed onto the windscreen produced very "odd visual effects"
3. Valentich deliberately disappeared or ended it all, hoaxing the sighting as part of it
- Complete disappearance of plane suggests this, DoT investigators also seem very interested in his relationships, mood etc
- Voice during incident described as matter-of-fact rather than surprised or concerned
- DoT report makes the point that the case had attracted "charlatans" and concludes that no-one would likely ever know the truth about his mental state, (without coming out and saying what they seem to imply)
- Totally contradictory stories about why he was flying, with an implication he wasn't going where he said he was
- Described as someone who bottled problems up; he'd not only concealed his failure of his commercial licence exams to family and colleagues, he'd actively lied about passing them; the DoT described all this as a "facade"
- Facing possible withdrawal of his private licence too. Flying was clearly important to him and he felt he had to prove to others he could make it his career despite being academically weak
- A colleague mentioned an unspecified family argument a few weeks earlier; Valentich Sr also felt his girlfriend's story about planning to go out with him later that day was "fishy"
In short it's a mystery with lots of disjointed or circumstantial evidence onto which it's quite easy to project whichever solution you feel comfortable with. For the incident itself we are completely reliant on what Valentich said to Melbourne Flight Service. I don't know - I have a feeling that it was possibly a mystery Valentich intended to create, but whether he did so consciously, I doubt we'll ever know.