Hi Bob/Richard and everyone else,

Have a question regarding no aid aerodromes and alternates.

For an aerodrome like Tumut, which has only an RNAV approach, if we fly there by day with a TSO129 GPS, we would require the minimum forecast to be no more than sct below LSALT+500 and 8km vis, otherwise we shall provide an alternate. This is based on the fact we treat Tumut as a no aid aerodrome.

However, if we have a TSO145/46a GPS we can treat Tumut as an aid aerdrome, BUT, since Tumut has no TAF, we must automatically provide for an alternate regardless of what the weather conditions are!

It seems strange that we should be so called penalised to provide an alternate straight up for Tumut if we have 145/146 GPS, but we can have chance of not needing an alternate if we have a lower TSO129 GPS, even if it is a picture perfect day!

Any thoughts on this? Have I missed something very obvious here?

Thanks, and looking forward to the response

Yes, this is a common question and, quite frankly, I don't know the answer. I have never got an adequate reply from CASA either. It seems strange that you can plan to an aerodrome without a published instrument approach without an alternate by reference to the ARFOR. But you cannot do the same for an aerodrome with no TAF, even on a perfectly clear day. What decides whether you need an alternate or not is simply the existence of a piece of paper with an instrument approach printed on it. If there is no instrument approach, you can base your decision on the ARFOR, but if there is an instrument approach published for that aerodrome, you must have an alternate no matter what the ARFOR says. Weird.

By the way, you would still need an alternate if you only had a 129 TSO GPS because you cannot plan to do an RNAV/GNSS approach with a 129 unless there is a ground-based aid at that airport as well.

Hi Bob,

Thanks for the response.

I thought that the TSO 129 would be fine in this instance as you would treat Tumut as a no aid aerodrome, and hence could use LSALT + 500 and 8k vis and get around the fact Tumut doesn't have a TAF, so no need for an alternate if the weather is good?

Cheers,
Brendan.

Trouble is the AIP doesn't say you can use LSALT + 500 and 8k vis when the aerodrome has no AID. It says you can use it only when the aerodrome has no INSTRUMENT APPROACH. An RNAV/GNSS is an instrument approach, so this aerodrome does have an instrument approach. The AIP says you cannot use the ARFOR for alternate planning unless the aerodrome has no INSTRUMENT APPROACH published. I know that's crazy but it is what the AIP says. I hear that some individual CASA FOIs have given opinions on this, but isn't it about time that someone amended the AIP to make it clear. I'm sure that you will find theory examiners keep away from this nonsense. Pilots all over Australia have been ignoring it for years. It means that, according to the AIP, you can never go to some homestead strip or any aerodrome without a TAF without an alternate - even in the middle of winter with a clear blue sky. Surely that was never the intention of the people who wrote it in the first place.

How come Tumut for example, which only has an RNAV, cannot be treated as a no aid aerodrome, but Corryong, which also only has an RNAV approach, can be treated as a no aid aerodrome with a TSO129, and therefor can use LSALT + 500 and 8k vis from teh ARFOR? (page 3.7 of IREX)

I was under the impression that if the aerodrome only has an RNAV, and you carry a TSO 129, you treat it as though the aerodrome has no aid, and use the ARFOR for LSALT + 500 and 8k vis? BUT if you had a 145/6 then you treat it as an aid aerodrome and therefor require a TAF or an alternate is required.

In my book I have adopted the common-sense approach that, if the aerodrome has no instrument approach that you can use, you could treat it as an aerodrome with no instrument approach and therefore you could use LSALT + 500 and 89 km vis. In my previous post I was simply pointing out that that is not what the AIP actually says. If you find any examples in the book where I have said otherwise please let me know. As far as I know, examiners would also make that interpretation.

ah ok, thanks for the clarification Bob, makes more sense now!

Cheers,