I was a pilot with Ausralian Air Charterers back then and was rostered to look for Fred in a Chieftain, VH-MBT. Spent about 6 hrs grinding up and down over the entire flight path with 8 CASA or DOT (whatever they called themselves then) people staring out the windows. Not a thing, not an oil slick, nothing, very strange. I remember a similar mission looking for Dr Ian Tippet missing in a PN68 off Wilsons Prom, found seat backings, oil etc almost straight away, but Fred, nothing. However a hazy sort of day and I still think it was a case of the 'Leans', followed by a loss of control. As for the lights above his head, it must remain a mystery.