Originally Posted by
eglnyt
It wasn't NAS, it's a completely different system.
That explanation in the report isn't clear but it seems to have found the Entry Point but not the Exit Point. If it can't find the Exit Point it apparently then searches for Waypoints beyond the border, presumably stepping out a step each time it doesn't find any of those in the plan. It found one of those in the plan but, because the waypoint in the plan was a duplicate of one surrounding the UK FIR, became confused because that waypoint wasn't correct in a geographical context.
Sorry, I meant FPRSRA, not NAS... but I make no apology for the latter being a menace to this day!
And the report is indeed not terribly clear, I couldn't work out whether it was looking FORWARDS from the last known or looking BACKWARDS towards it, thus my question about 'doubling-back.' Easy to see therefore if it was reading forwards how it might find something and then realise upon finding it that it had already found it once before, in this case at the start of route. Still not sure how it would impact unaffected sectors so broadly on the basis of a single aspect in a single flight plan.