PN am fully aware of the limits, it does of course depend which AC you need to get thru etc. As far as an AC like the Buccaneer is concerned a top up at TOC (to more than one AC ) could be all that is needed to achieve the result. A lot would depend on the exact conditions on the day eg wind component and min fuel needed at destination. I don't actually remember any unaccompanied direct transits in 82 or 83 hence the question.