Alternate minima

[newifr]

Hi All

Just doing some pre study for my IFR course and have a few questions on Canberra ILS 35.
1.ALTERNATE. (1964-4.4) does that mean if you had cloud overcast at say 1800ft and vis 3.0Km that you must plan an Alternate for Canberra if Canberra is your planned destination
OR
Does it mean that if you plan Canberra as your alternate your TAF must be better than (1964-4.4)
2. What does S-I ILS mean as opposed to ILS.

Don't know why we practise Canberra approaches when we fly out of YMMB.

Thanks

newifr

[blueloo]

I don't have the figures for Category A & B aircraft on my Jepp chart, but if the back of the aerodrome chart has your figures "for filing as an alternate" (actual or forecast QNH [100' diff]) 1964' and 4.4 km vis then, if either of the forecast cloud height* or visibility is less (and both are in your example) then yes you will require to plan an alternate.

And yes if using Canberra as your alternate, its forecast must be better than this as well.

S-I = Straight In Landing. Presume it means instead of Circling to Land (off the ILS) which has a higher minima.

[newifr]

Thanks blueloo

However on the CASA approach plates there are no Alternate minima stated on either page of the aerodrome chart.

The only place I can find alt minimas is on the approach plate itself.

[ConfigFull]

newifr,

You'll find that the alternate minima doesn't change between approaches - it's purely an aerodrome thing (ignoring Special Alternate Minima (SPAM)).

For both your examples, if the cloud base is greater than SCT below the alternate minima and/or the vis is less than the alternate minima then either an alternate, or holding, is required. Remember, an alternate cannot require an alternate itself.

[newifr]

Can you nominate an alternate which has holding assigned to it as long as you carry the holding fuel required at the alternate.?

Thanks

[waren9]

yes you can

[Keg]

Whether you'd actually want to is another question entirely! :ok:

[waren9]

i knew somebody would bring that up.;)

[eocvictim]

Southern frontal weather is a prime example when your nearest alt for Melbourne is Adelaide and even that needs holding.

[Capn Bloggs]

Whether you'd actually want to is another question entirely!
Sometimes it's not a case of "wanting" to! :}

[Wally Mk2]

All good advice from those posted here already:ok:

Aside from cloud base req's at yr destination (thread drift slightly but worth a mention) there are also c/w considerations with some getting caught out with a more into wind rwy actually being Notam'd out of service & not usable, lighting if that's applicable also needs to be considered as well as Viz due dust storm for Eg.
And remember that when considering an Alt AD it too must not also have the need for an Alt (as has been said already I think) & lastly the Alt AD must have a firm & valid forecast for yr arrival otherwise it too needs that Alt (as mentioned abv) if operating into it IFR.
All lots to think about. The rules/regs are great but they are the bare min's req'd for legal reasons. As you get IFR hrs under yr belt you will soon learn that often especially around coastal dromes during winter you can never take enuf fuel:ok:
Enjoy the ride, but don't do it in a SE plane:E:E:E

Wmk2

[Adsie]

Not that this matters to the scope of things but are you using Jepps or Air Services plates?

[newifr]

Adsie

Air Service plates.

[PPbash]

:ugh:
Don't know why we practise Canberra approaches when we fly out of YMMB.


A typical student response. Why not fly EN(ILS) 30 times and then do your test to Essendon. Why bother doing forced landing practice when you will never have an engine failure. Clowns like you flying around IFR are the tools that will eventually kill themselves. The simulator is there to train in different environments and fly different approaches, it’s called exposure. Good luck with your training, I feel sorry for your instructor.

One more, how are those rude people at CASA asking me a question in IREX about some NDB approach in NSW that I’m never going to fly to, I fly out of YMMB not YSBK.

I feel better now.

[The Wawa Zone]

Don't know why we practise Canberra approaches when we fly out of YMMB.

That's because someone who sets the syllabus just knows that the very first CB approach you'll ever ever do will be flown right down to the DA, about 5 hours after you get a call at home at 8pm to do a quick CB charter in VMC with a full moon. (And you'll get the SPECI on CB Approach..)
And that is what they're paying you for :)

[Tee Emm]

Don't know why we practise Canberra approaches when we fly out of YMMB.

That is an easy question. The flying school makes more money from you flying all the way to Canberra and back. With slight variations all ILS are basically the same so EN or AV are all you need to practice on. If the flying school wants you to practice at Canberra for whatever altruistic reasons then tell them you want to do it in a simulator or synthetic trainer. Saves a lot of money and is just as effective.

[Woodwork]

2. What does S-I ILS mean as opposed to ILS.

Hi newifr,

I assume you're using Airservices plates based on this comment. There are actually two - ILS-Y and ILS-Z - but the layout is the same. Each has five minima fields, as follows (using the ILS-Y, the -Z is the same but the MAP gradients are less):

S-I ILS (2.5% MAP) - this is the minima for a straight-in approach to RWY35, if you can meet the 2.5% MAP climb gradient.

S-I ILS (5.0% MAP) - this is the minima for a straight-in approach to RWY35, if you can meet a 5.0% MAP climb gradient (to 3200FT, then relax to 2.5%, explained in the plate notes)

S-I LOC/DME - this is the minima for a straight-in approach without glidepath guidance

CIRCLING - this is the minima if your approach will require circling, ie the ILS is the only suitable approach, but the wind velocity makes 35 operationally unacceptable to you.

ALTERNATE - the alternate minima for the airport.

Both the Circling and Alternate minima are the same for every approach, and in Canberra the alternate figures are a reasonably standard 500ft / 2.0km greater than the circling minima for the respective performance category.

AIP provides the guidance that:
Each approach chart shows the ceiling and visibility minima to be compared with meteorological forecasts and reports to determine both the need to provide for an alternate aerodrome and the suitability of an aerodrome as an alternate.

You should seek guidance from your instructors about what their expectations are regarding planning when your destination is at or near its alternate minima. The wording of the Regulations, and individual company policies, can vary widely on this point.

[27/09]

Do you guys use PANS-OPS over there for specifying minima requirements? i.e. When viz is forecast to be less than 5000m, or less than 2000m more than the required viz for that approach, (which ever is the greater of the two) and/or cloud base less than 1000 feet above MDA/DA then an alternate is required.

[Adsie]

The diiference between Y and Z plates are the missed approach performance gradients.

Alternate minima are on the aerodrome plate in Jepps if your looking for it

[aditya104]

Question: Does an aerodrome need an alternate if there is no TAF available? Or can it proceed to the destination without planning for an alternate provided that: not more than SCT cloud is forecast below the final route segment LSALT+500ft and the forecast visibility not less than 8km.

[Woodwork]

The diiference between Y and Z plates are the missed approach performance gradients.

Yes, that's quite perplexing. The two approaches seem otherwise identical. I can only presume the higher MAP gradient on the Yankee is designed to protect against more than just terrain.

[Capn Bloggs]

I can only presume the higher MAP gradient on the Yankee is designed to protect against more than just terrain.
Simple really. If you can hack a higher gradient during the Missed Approach, you can go down to a lower Minimum. The limiting obstacle is at a set distance away: the lower you are when you start the MA, the steeper gradient you have to achieve to get over that obstacle.

[PPbash]

That is an easy question. The flying school makes more money from you flying all the way to Canberra and back. With slight variations all ILS are basically the same so EN or AV are all you need to practice on. If the flying school wants you to practice at Canberra for whatever altruistic reasons then tell them you want to do it in a simulator or synthetic trainer. Saves a lot of money and is just as effective.


As if, do you really think a flying school in MB takes a student to CB for an ILS? Tee Emm, you’re not all related to that poor guy in a wheelchair from south park, timmy?

[Woodwork]

Simple really. If you can hack a higher gradient during the Missed Approach, you can go down to a lower Minimum. The limiting obstacle is at a set distance away: the lower you are when you start the MA, the steeper gradient you have to achieve to get over that obstacle.

I think you might have me confused. I'm not talking about why you have different gradients for different minima - that's self-evident. I'm wondering why two different approach plates are produced for exactly the same approach.

The ILS-Y SI minima, not adjusted for QNH, are 2440/2.3 for a 2.5% MAP, and 2170/1.2 for a 5% MAP. The ILS-Z minima are the same for a 2.5% MAP, and split the difference at 2300/1.5 for a 3.3% MAP. That is the only difference between the approaches. Surely the good folks at ASA could save a page in DAP and a few megs of memory in the flight bag by inserting the 3.3% MAP gradient into the ILS-Y plate, and decommission the ILS-Z? That's what's perplexing, why we bother with two plates that reproduce identical information.

That, in turn, got me thinking that perhaps ATC might need to clearly indicate they need a good, strong climb in the MAP to protect against nearby airspace or a STAR, but then now I think about it, ATC wouldn't know which climb gradient you're capable of achieving, so that was a silly thought.

Probably some rule somewhere that you can't have more than five minima fields per plate or something.

[newifr]

Thanks for all the posts. It has been very informative.

newifr

[brown_eyes]

Just returning to Oz after a few years overseas and was wondering if there has been any changes to the requirements on the Fixed Reserve.

1. Is the Fixed Reserve sacred or can it be used?

2. If it can be used under what circumstances?

[bentleg]

1. Is the Fixed Reserve sacred or can it be used?

2. If it can be used under what circumstances?

Answered in a separate thread (http://www.pprune.org/dg-p-general-aviation-questions/458137-fxed-reserve-use.html)