For the RAAFies: Standard Alternate Minima: R U happy w/ the current definition?

[Trash 'n' Navs]

In the old days, the Standard Alternate Minima in FIHA used to come in a table format but now appears in a text version. Everyone I've spoken to liked the old table format yet it changed. Who else would like it back in the table format or are you happy with the current version?

Whilst I have the opportunity, I'll ask the curly one. Do you think the requirements are still appropriate? As far as I can tell they haven't changed since the time of Adam & Eve and yet no-one knows where they came from originally. I've had a quick look at what overseas regulations dictate and they do differ. In fact, the ICAO requirement is vastly different.

ICAO Annex 6 (Operations of Aircraft) Part I states:
4.3.4.3 Destination alternate aerodromes For a flight to be conducted in accordance with the instrument flight rules, at least one destination alternate aerodrome shall be selected and specified in the operational and ATS flight plans, unless:

a) the duration of the flight path and the meteorological conditions prevailing are such that there is reasonable certainty that, at the estimated time of arrival at the aerodrome of intended landing, and for a reasonable period before and after such time, the approach and landing may be made under visual meteorological conditions; or

b) the aerodrome of intended landing is isolated and there is no suitable destination alternate aerodrome.

Annex 6 Part II Chap 4 states
4.6.2.1 When a destination alternate aerodrome is required. A flight to be conducted in accordance with the instrument flight rules shall not be commenced unless the available information indicates that conditions, at the aerodrome of intended landing and at least one destination alternate will, at the estimated time of arrival, be at or above the aerodrome operating minima.

4.6.2.2 When no destination alternate aerodrome is required. A flight to be conducted in accordance with the instrument flight rules to an aerodrome when no alternate aerodrome is required shall not be commenced unless:

a) a standard instrument approach procedure is prescribed for the aerodrome of intended landing; and

b) available current meteorological information indicates that the following meteorological conditions will exist from two hours before to two hours after the estimated time of arrival:
1) a cloud base of at least 300m (1000ft) above the minimum associated with the instrument approach procedure; and
2) visibility of at least 5.5km or of 4km more than the minimum associated with the procedure.

Para 4.6.2.1 basically says you only need WX better than the nominated app minima at the destination and one nominated alternate. Otherwise, it's 1000FT & 4km extra for two hours either side of ETA. Now that's a lot and ICAO obviously allows States to vary these requirements, but what do the other States do?

Having read the FAA Reg's, Canadian AIP's and the NZ AIP's, my understanding is that you must nominate an alternate but your destination only requires WX above the minima specified on the approach you intend to fly. Your ALTERNATE, however, requires 800FT HAA & 2 miles vis (non-precision app) or 600FT HAA & 2 miles vis (precision app). TERP's has slightly reduced numbers.

The 800/600 FT actually approximates what we do now by adding the 500FT & 2000m.

The difference, though, is that we apply it to the destination and have removed the requirement to nominate an alternate. The advantage is that you now don't have to carry the fuel for the alternate when planning your sortie.

Aust AIP's have a different rule again to the FAA et al. Should we adopt their method? Should TERMA include the alternate minima (like DAP's) bearing in mind that they're calculated on the circling areas and not the SIA minimas?

So do you agree with our Std Alt Min or do you think we should consider changing them? Are they still appropriate? Who should decide the rules?

Just wondering.....

[Booger]

Phew... H-e-a-v-y, but here goes:

I always cringed at the text definition of SAM and put it down to one of those pesky things you had to learn before your IRT quiz. Whilst the SAM concept is relatively straight-forward (especially after it's hammered home on course & umpteen IRTs) I found that the table was much more user friendly than the text, let's face it - aircrew are more "picturate" than "literate".

I would go one step further and say that a non-standard decision tree diagram (you know the ones - they had diamonds for yes/no branches etc...) a stud came up with on Pilot's Course was the best method of clearly determining SAM requirements. I only wished I had kept a copy!

The one thing that I loathe is placing buffers on minima. I believe all plates should have viz & cloud requirements that are the actual limits. You look at your weather, look at your destination app aids and compare: easy. Here's where I expose my lack of aviation experience - do Aus civvy flying requirements dictate similar 2000m & 500' buffers for SAM, or is that a RAAFism?

Don't know about adoption of ICAO vs US/Can/Eur requirements, I'm surprised that ICAO isn't the cut & dry authority.

One thing's for sure, I'm stuffed if I'll EVER be able to remember all those definitions for IMC/VMC approach requirements by day/night! (30km, in sight of ground or water, mother's maiden name multiplied by the number of spanners in a Sidchrome tool set... etc...)

:D

[L J R]

...at least Mil procs don't give you night minima. [just in case your ILS set doesn't work in the dark.

Some of us remember the 'good' ol' days when the text was replaced by the tables c 1983??. Now that was progressive. Goog to see the wheel turning.

Booger are you going for an IRE cat.?

[Surditas]

Never saw the tables, but they sound like a good idea. I am like Booger and have only learnt the SAM via having it hammered into me at various IRT's. The way it is writ in FIHA does not promote easy understanding.

Or maybe I am a bit simple. :confused:

The civvie plates are easy enough to figure out, maybe TERMA should head that way, too.

As for not following ICAO, it would be interesting to know why it went that way.

[Trash 'n' Navs]

Booger Funny you should mention the "decision tree diagram" because I have recently seen the FLIP SAM section that preceeded the old AIP Blue Pages - and it was a tree diagram. When RAAF migrated away from FLIP, someone interpreted those tree diagrams in to the text version (which then went to a table format and now back to text!).

I agree with you that it would be handy to have your alternate minima on the plate in front of you thus removing all debate and headache. DAP's do have this feature and if you look at some of the minima boxes, the bottom line has the "Alternate" details. Also, the civvies are allowed to use an extra "Special" alternate minima that's on selected plates provided they've got twin ILS/VOR, twin DME & twin marker beacons (I think that's right).

As for the 500FT & 2000m, it's not a RAAFism - we both use it but in different ways. The alternate minima provided on DAP's plates is calculated by adding the 500FT & 2000m to the circling minima and not the SIA minima that we can use. The reason the civvies do this, I have on good authority, is so that Met Section can determine when they need to issue SPECI's. Consequently, a standard method is used across the board and the easiest way was to use the circling minima. To confuse the matter, if you look at the AMB ILS B RWY 15, you'll notice two circling minimas. If we were to use the civvy rules, we'd be bug gered because you couldn't list a single "alternate minima" for AMB. So you can see that whilst the civvy method is simpler for us drivers, it does restrict us by using the circling minima v. SIA minima.

The point about not following ICAO specs is not isolated to Australia. The US, Canada, UK, NZ and no doubt others have all published different rules as permitted by ICAO to suit local circumstances. The civvy specs are listed in the CASA MOS Part 2 para 1.8 "IAL Design Criteria Standrads and Minima Determination" (avail on the web).

I would like to ask you all again - are you happy with the 500FT & 2000m buffer? Are you happy with how it is applied? Is it still appropriate? Or should we look to the US, for example, who use a flat 800FT HAA & 2 miles vis for alternate calculations?

Trash

PS Surditas Yes mate, you are simple! :p :) :D

[Surditas]

Yes, if I wasn't so simple I would have figured that out for myself!:D

I think 500ft and 2k works quite well, but it would be easier if the tables came back.

PS: I have passed your original post around via email, Trash and it is generating discussion here. I will email replies I get to you.

[Booger]

Trash - I'm content with the 500'/2000m, but only because I abhor change! I'm too old to go learning anything new.;)

L J R - no, not going for an IRE but I am about to be lobotomised... I'm going on FIC.