Originally Posted by
Agaricus bisporus
means very close to ABZ indeed, to my mind inside 10 miles. If, and I repeat "if" the pax really means "on approach" as opposed to "inbound at an unspecified distance" then any airprox will be observed by radar, and in any case will be reported by the crew and appropriate follow-up action taken. Given that he described a "light aircraft" it is unlikely to be offshore by more than a mile or two unless it was a fisheries patrol craft.
Either way fear not it will be logged, reported and processed if appropriate. (ie if it happened as suggested)
Not necessarily (although acknowledging that you say "if appropriate"). An encounter with another aircraft requiring a direction change to avoid becoming uncomfortably close is routine and not necessarily an Airprox. It only becomes an Airprox if one of the crew considers there was risk of collision. With VFR on VFR or VFR on IFR as I said, even though ATC have the power to tell you what to do, they have no obligation to stop you crashing into each other, only one to tell you of the existence of the other traffic. So it would seem unlikely that they would take it upon themselves to file an Airprox. That would normally only happen with IFR on IFR or if an a/c had violated the airspace or their clearance.