Greengage22 - Sometimes it is the punctuation that can confuse, or the reader not realising the significance of paras, sub-paras etc. Allow me to quote from our Ops Manual with regard to 4 eng a/c:
(b) Destination
QTE
At least one destination alternate must be selected for each IFR flight unless:
(i) Both:
1. the planned duration of the flight from take-off to landing does not exceed 6 hours; and
2. two separate runways are available at the destination and the met conditions will support a VMC approach & landing from the MSA for one hour before and after the aeroplanes ETA.
(ii) The destination is isolated and no adequate destination alternate exists. UNQTE
So you see that items (i) and (ii) are two different scenarii when an alternate is not required and each will have their own caveats.
If using scenario (i), then you need taxy, trip, contingency and Final Reserve (30mins), PLUS an ADDITIONAL 15 mins holding at 1500ft above aerodrome elevn based on ISA conditions. The caveats for not having an alternate for scenario (i) are items 1. & 2.
When operating to the Isolated Aerodrome Procedure, which is scenario (ii) in blue, then a separate section will describe the planning requirements. Let's look at what is required in this situation:
You need taxy, trip, contingency and:
QTE:
additional fuel if required, but not less than the fuel to fly for two hours, calculated with the normal cruise consumption, after arriving overhead the destination areodrome, including final reserve fuel; and extra fuel, at the discretion of the commander. UNQTE.
Here, the punctuation misleads!! In essence, what you need is an extra 2 hrs cruise fuel which is IN ADDITION to your final reserve.
The Computerised Flt Plng system we use will calculate this 2hrs continuation of cruise assuming LRC at FL 300, irrespective of the cruise mode and FL used to o/h destn. So you're getting 2hrs fuel upstairs and 30 mins downstairs!!
As an adjunct, isolated aerodrome procedure used to be known as Island Holding, but destination does not need to be an island for this proc, it could be somewhere in the middle of Siberia, or even worse, Oz!!.... (joke guys )
Hope this helps GG22. If not, feel free to e-mail