Minimum Fuel Required - No Destination Alternate / 'Isolated Airfield'

[greengage22]

JAR-OPS makes a distinction between the 'no destination alternate' case and the 'isolated airfield' case and I don't understand the difference. Can anybody help?

IEM OPS1.255 states that normal fuel policy is taxi fuel, trip fuel, contingency fuel, alternate fuel and final reserve fuel. Additional fuel for 15 minutes hold at destination is also required when a flight is operated without a destination alternate.

It then goes on to say, in a separate paragraph, that for a flight to an isolated aerodrome for which a destination alternate does not exist the minimum fuel is taxi fuel, trip fuel, contingency fuel and, (for a jet) fuel to fly for 2 hours, including final reserve fuel. Now, since final reserve is normally 30 minutes, this means that you need an extra 1.5 hours at normal cruise consumption.

For case (1), it seems, you need an extra 15 minutes at hold consumption plus the alternate fuel, whilst for case (2) you need and extra 1.5 hours at cruise speed and no alternate fuel.

Practically speaking, what's the difference between the 'no alternate' case and the 'isolated airport with no alternate' case?

How can you have an airport with no alternate unless it's 'isolated'? And why the difference between the 2 sets of figures?

Anybody know?

[411A]

Island reserve...used for years.

[greengage22]

Thanks for responding, 411A, but I'm not sure that I've really understood your reply.

Do you meand that the 'island reserve' fuel is the extra 15 mins hold fuel or is the 2 hrs cruise fuel? And what is the distinction between a flight 'without a destination alternate' and 'isolated airport without destination alternate'? How can you have a destination without an alternate unless it's isolated?

In a recent post about non-normal fuel reserves 4PON4PIN posted a very helpful reply. If he (or anyone else) can shed light on this, I'd be happy to hear from him.

[4PON4PIN]

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 ) :D

Hope this helps GG22. If not, feel free to e-mail

[greengage22]

Thanks very much, 4PON4PIN. Very helpful