AJ wrote
My question is this: When should the pilot of a commercial jet dump his
fuel in flight? He obviously wasn't going to do that and was going
to land very heavy. Under what conditions is fuel dumping necessary.

As a former B-707 PIC, I would dump fuel if an emergency forced a
landing at an unplanned airport with a too short runway, or if the
maintenance staff at the airport was not equipped to handle the
necessary 'overweight landing inspection' if fuel were not dumped.

The fuel on the KLM B-747 would not have put it anywhere close to
maximum landing weight at Las Palmas.

We often 'tankered' extra fuel based on the price differential between
different airports.

Bob Moore
ATP B-707 B-727
PanAm (retired)