Originally Posted by
finncapt
Island reserve has been mentioned.
The VC10 was, often, unable to divert from Bermuda to a mainland US airport, on a flight from the UK, so we took island reserve.
If I remember correctly, this allowed for 21/2 hours holding overhead Bermuda at 10000? feet (20 tonnes?).
It was for the blocked runway situation, although, I seem to recall, there was a "cross" runway in those days which was usable with sufficient wind.
The aircraft set off, a "last point to turn" was calculated, at which a decision was made to continue if a landing was assured or to divert to the US mainland.
This could be before top of descent.
Others may be along to correct my memory.
Another option was a tech. stop in Shannon, or the Azores, although I never did that.
Once I was tasked with planning DC8F operations thru Isla de Pascua (Easter Island), flying fish to Japan, 'Island Reserve' was the only option but no chance of making it to Chile before the tanks would run dry