vilas,
Practical is carry extra and burn it before landing but not allowed to do so unless you manipulate the BO.
You may load extra fuel up to your Take Off limited RTOW.
You have to consume surplus fuel (e.g. by holding) to ensure you are below maximum landing weight. Hence adjust the planned burn for the load sheet calculation.
Practical is to carry minimum fuel and burn alternate if you find weather OK and land. Not allowed legally.
When operating to an isolated airfield (say Seychelles), inflight fuel management allows use of decision point.
"Decision Point: The nominated point, or points, en-route beyond which a flight can proceed provided defined operational requirements, including fuel, are met. If these requirements cannot be met the flight will proceed to a nominated Alternate Aerodrome.
Note 1: The operational requirements required to be met are specified by the operator and approved, if required, by the State.
Note 2: Once past the final Decision Point the flight may not have the ability to divert and may be committed to a landing at the destination aerodrome."
Bergerie 1, in his VC10, may have elected to make his decision point say 10,000 ft on the descent. Weather at destination was CAVOK, he was number one for the approach and thus a successful landing was assured. If he decided Landing was not assured, then he could easily have diverted to Mombassa with all Reserves intact.
He was overweight for a straight in approach, so elected to "hold" by doing a visual circuit around the Island and landed below Max Landing weight at his destination.
Which bits are "Not allowed legally"?