The draft CAAP clearly refers to fuel remaining at the destination aerodrome and the accompanying proposed change to the Regulation will make it an offence to ARRIVE without that reserve on board. As someone who knows more than I said, "they want to have something absolute to measure, Kaz."
"FIXED FUEL RESERVE – the amount of fuel, expressed as a period of time, required to fly at holding speed at 1,500 feet above aerodrome elevation at ISA conditions, calculated with the estimated weight on arrival at the destination alternate aerodrome, or the destination aerodrome when no destination alternate aerodrome is required, that would be useable fuel remaining in the fuel tanks until completion of the final landing."
The current Regulation CAR 234 just as clearly refers to the fuel uplift at TAKEOFF.
" (1) The pilot in command of an aircraft must not commence a flight within Australian territory, or to or from Australian territory, if he or she has not taken reasonable steps to ensure that the aircraft carries sufficient fuel and oil to enable the proposed flight to be undertaken in safety."
Be aware also, that there are more calculations required both pre-flight and in-flight, and a Fuel Mayday must be called if the total remaining fuel falls below the mandatory minimum fixed reserve. Call it and you get pinged, of course! That will undoubtedly encourage transparency and full compliance.
Finally, you have to use aircraft specific fuel consumption data taken from the AFM, or the engine manufacturer if not available. Only where no specific fuel consumption data exists for the precise conditions of the flight, may the aircraft be operated in accordance with estimated fuel consumption data.
Kaz