....was on final to land with 30 mins fuel remaining (ie no diversion fuel)
Can be worth clarifying this is "30 mins holding" -
not 30mins flying. A GA and optimal visual circuit might only take 7-8 mins, but will use, for an Airbus, ~50% of this fuel as a minimum. Any sort of radar circuit - even a tight one, will be using 60% as a minimum, therefore basically there might be only "one shot" left
I can't imagine other types are far off this either...