The relevant regulations and other references This publication should be read in conjunction with regulations 220 and 234 of the Civil Aviation Regulations (CARs) 1988.
Who this CAAP applies to This CAAP applies to all operators of Australian aircraft.
Why this CAAP was written This CAAP provides information and guidance on fuel requirements for aircraft required by regulations 220 and 234 of CAR 1988.
As I said, para 5.1 seems straight forward in defining sufficient fuel.
When you decide to use your fixed reserve LB, are you in the enroute phase of flight or are you using unplanned manoeuvring in the vicinity of the aerodrome?
Doesn't enroute phase stop at 1500 feet above the aerodrome?
From that CAAP
fixed fuel reserve means an amount of fuel, expressed as a period of time holding at 1 500 feet above an aerodrome at standard atmospheric conditions, that may be used for unplanned manoeuvring in the vicinity of the aerodrome at which it is proposed to land, and that would normally be retained in the aircraft until the final landing.
and para 5.1
5.1 Where it has been determined that an alternate aerodrome to the destination aerodrome is not necessary, the amount of fuel on board an aircraft at any particular point in the flight should be an amount that is sufficient:
(a) to enable the aircraft to fly from that point to a height of 1 500 feet above the destination aerodrome, make an approach and land; and
b) to enable the aircraft to continue to fly at a cruising speed for a specified percentage of the time that it would take to fly in accordance with paragraph (a), being the percentage specified in Table 1 of this CAAP for that category and class of aircraft; and
(c) to provide for contingencies of the kind described in section 6; and
(d) to provide holding fuel to take account of any traffic delays of the kind mentioned in paragraph 4 (c); and
(e) to provide the fixed fuel reserve that is specified in Table 2 of this CAAP.
Note it says the above fuel on board during any particular point in flight for it to be sufficient. Once you are 1500 feet over the aerodrome you are landing at, you are now in the arrival phase of flight. Fixed reserve can now be burnt if needed by any unplanned manoeuvring, but will normally be retained until final landing .
Fixed reserve is not for traffic holding .It's not for stronger than expected winds . It's not a range extender fuel.