I had a similar situation about 15-16 years ago. Flying back from LOS on VS and there was a fuel shortage in LOS at the time. We flew LOS-ACC to top up. The crew were bartering crew meals with the fuel loaders to try and get enough fuel to get back to LHR. Once the fuel loading was completed with as much fuel as they would load, the Captain came over the PA and announced that we just might have enough fuel to get back but there was a possibility we may have divert to either CMN or MAD. We would also be flying at a much slower speed to conserve fuel.

We we did make it to UK airspace but ATC were going to put us into a hold so the captain diverted to LGW to refuel. Sat on the ground for about an hour before taking one of the shortest flights in a 747. Was near 11 hours from LOS-LHR that day.

S