Question on Approach Plates

[Greedo]

G'day, A question regarding approach plates: When the MSA is split into different sectors, for instance at YCFS, and the different sectors are shown with respect to the VOR, it has always been my understanding that whatever sector the text appears in (for the relevant radial or bearing) that is the height that applies to that radial.So in the instance of YCFS - the 25 NM MSA for the 205R is 5500 - the 25 NM MSA for the 030R is 5500 - the 25 NM MSA for the 160R is 2500therefore by ommission, the 3300 MSA sector is from the 161R to the 2045R, as one example.Am I correct? If not, how so you know what is the approriate heights for the splits in MSA sectors?Secondary Question: If you are established on the 205R at YCFS for the VOR-Z RWY 03 at 11NM, what height should you be at and why? 5500? 3300? 1900?Please enlighten me,Greedo

[skkm]

Secondary Question: If you are established on the 205R at YCFS for the VOR-Z RWY 03 at 11NM, what height should you be at and why? 5500? 3300? 1900?

This one's perfectly simple, look at the vertical profile. At 11 NM you can be at 1900 if established on the 205ºR. Preferably you'd be a lot higher so as to be closer to the 3º profile, but there's no requirement of such.

[Bladeangle]

Tracking 025 inbound your safe at 3300' within 25, you might be on the fence but your not over it...

Re the approach, 3140' at 11nm on profile.

[LongLats]

Secondary Question: If you are established on the 205R at YCFS for the VOR-Z RWY 03 at 11NM, what height should you be at and why? 5500? 3300? 1900?

If you mean, what's the lowest can you be, it's 1900' provided you are on the 025 degree track to the VOR. The moment you go out of tolerance on that bad boy, you are no longer protected by the VOR approach so would be in trouble. Tolerance on a VOR is 5 degrees, which is half scale deflection of the VOR.

So if you find yourself greater than half scale deflection to the right of track, the lowest you can be whilst protected is 3300' as you fall in that quadrant of the 25nm MSA. Find yourself greater than half scale deflection to the left of track, the lowest you can be is 5500' because you fall within that part of the 25nm MSA.

The idea with IF flying when you're approaching an aerodrome, is always trying to find a way to get as low as possible so you can get visual and get on the ground. You're always looking at approach steps, 25nm MSAs, 10nm MSAs and route LSALTs to find a safe way down. Just remember you're only protected by these things if you're on track.

That is if you're wondering what the LOWEST you can be is at that point. If you want a smooth, constant descent down the the MDA, the way the approach was designed, you would want to be 3140' at 11nm. That number is straight off the plate.

[DeltaT]

Re Q1 MSA, I've had a look for a reference and can't find one, but I was taught to look at it going clockwise around and the step occurred after the radial, so R205=3300, R030=5500, R160=2500

[skkm]

The moment you go out of tolerance on that bad boy, you are no longer protected by the VOR approach so would be in trouble. Tolerance on a VOR is 10 degrees, which is full scale deflection of the VOR.

AIP says you must be 'established' on the VOR track in order to descend on the approach –*that is 5º or half scale deflection.

[LongLats]

AIP says you must be 'established' on the VOR track in order to descend on the approach –*that is 5º or half scale deflection.

You're right, well picked up. My bad!

[FGD135]

If you apply some logic, you will realise that you are perfectly safe at the lower MSA when flying along those radials that denote the sector limits.

In this case, for example, you are perfectly safe at 3,300 whilst tracking the R-205 and also perfectly safe at 2,500 on the R-030.

There are lots of "logic lines" you can apply to this question. Here is just one:

If you weren't safe at 3,300 on the R-205, then this would mean that you are safe on the R-204 but not the R-205. And being really pedantic about it, you could stretch that meaning to say that you are safe on the R-204.9 but not safe on the R-205.0. Is it logical, or likely, that a difference of 0.1 degrees of radial would make the difference between safe and unsafe?

No.

[Wally Mk2]

ALL inst App's, sectors etc are surveyed out to well beyond what's shown on any chart. Years ago if I recall when the divided up diff Cat trks for eg on a NDB App from overhead the aid there was more than 5 deg's between say cat B to Cat C then someone said hang on a minute if I am Cat B going 360 outbound (Due Nth) & the Cat C was 008 outbound does that mean he's safe in my no-go-zone?

Anyway good situational awareness is everything.


Wmk2

[Tinstaafl]

Slight point, Greedo, but those are *altitudes* ie referenced to MSL, not heights.

[Capt Claret]

The idea with IF flying when you're approaching an aerodrome, is always trying to find a way to get as low as possible so you can get visual and get on the ground.

I suspect the majority of the world's jet & larger turbo-prop operators might disagree with that philosophy.

Re Q1; agree with FGD135.

Re Q2; the philosophy is that most approaches are designed to be flown at a constant descent to the threshold, usually 3 degrees. So for the 03 VOR, one would ideally be at 3140', descending at 320'/nm, and either become visual in time to continue the decent below the MDA, or go around.

Given that one can't be below 3300' until passing 12DME, to reach 1900' by 8 DME would require a descent rate of 350'/nm, only marginally greater than the design rate. Further to achieve 1900' by 11DME (1400' loss in altitude in 1 nm :eek:) would require a chopper, Harrier, or a horrendous rate of descent as one is getting closer to the ground, and wouldn't be considered stable by any stretch of the imagination.

[ZAZ]

AIP says you must be 'established' on the VOR track in order to descend on the approach –*that is 5º or half scale deflection.

At FAF?

Not below and within the 5 degrees until established on final approach.
And isnt that two dots on the VOR scale?

Intermediate or outbound from VOR you can be off track and descending below the Altitude over the AID and on your way outbound to the FAF and still able to make a cut to regain tolerance (2 dots and closing), can't you?

[ZAZ]

The idea with IF flying when you're approaching an aerodrome, is always trying to find a way to get as low as possible so you can get visual and get on the ground.

BS :=

I did that one day at EN and the controller said, I dont' know what sort of approaches you do out where you come from old boy, but we have rules and procedures here.



A few weeks ago on way from MIA to HSM the TAF was changed to 30% PROB T/S and RASH CB.
OOPS There went the ALTN
Down from 7, to 5, to 4.6 then 4.1 then maintaining terrain clearance visually

Destination AD had TEMPO overcast at 800 feet.
Felt disinclined to fly all that approach and maybe miss out go to an ALTN.
had to get to a funeral (literally).
So Flew in VISUALLY scraping the fences from 30 miles out following the railway line (true story) just like I did 30 years ago when I was VFR and knew no difference...

It is a UA and my hair was standing on back of neck.
Scraped in over the Grampians and when I reported my arrival I swear I heard CENTRE sigh with relief and he actually said THANK YOU to me when I cancelled SAR.

CENTER even offered to find me an Alternate that day, how neat is that?
But nah I knew better...


And when I was refueling I could hear the high speed engine noise coming like a train out of the north and a 210 flew out of the crap and over the AD doing about 200 knots southbound at about 300 feet.

Yep aim of the game is to get on the ground one way or another, thats for sure...:ok:

Cheers...

[Delta_Foxtrot]

25 and 10 nm MSA sectors include a 5 nm buffer around the sector. Ie the 25 nm MSA includes any obstacles and terrain out to 30 nm from the ARP or NAVAID. For multiple sectors, think of them as if they are clean cut from a cheese circle, then have an even mould coating all around the lateral edges.

[skkm]

At FAF?

Not below and within the 5 degrees until established on final approach.
And isnt that two dots on the VOR scale?

Intermediate or outbound from VOR you can be off track and descending below the Altitude over the AID and on your way outbound to the FAF and still able to make a cut to regain tolerance (2 dots and closing), can't you?

At any point inbound (even before the FAF) you need to be established within 5º (2.5 dots) in order to descend.

Outbound from the VOR, yes, you can be off track "on a heading to intercept" the outbound track.

[43Inches]

To be correct only on a reversal procedure can you descend outbound without being established on track. As long as 1, you passed over the aid within 30 deg of the outbound track or if the base turn is greater than 30 deg are within the area covered by the inbound track to the outbound track and 2, are on a heading to intercept the outbound track.

The idea with IF flying when you're approaching an aerodrome, is always trying to find a way to get as low as possible so you can get visual and get on the ground.

The idea with IF flying is to operate safely under the IFR.

When approaching an aerodrome you need to assess which minimums and approaches will achieve the safest arrival with a level of efficiency given the conditions. If its VMC just a visual approach is all that may be required. Conditions IMC below MSA but above circuit maybe a DGA or non-aligned to a circuit or circling, if conditions are fluctuating around circling minima I would go for a straight in if possible. It also comes down to how much you trust the actual weather indications provided to you and any other local factors.

Getting as low as possible as soon as possible is not necessarily safe or efficient depending on a lot of factors. If it's close to minima on a circle and you have to do a missed approach the straight in would have saved a lot of time.

In regard to the original question about MSA sectors the AIP reference says you must remain within a sector. I suppose whether you call the boundary line within or not is open to interpretation, as others have said you won't be scraping hills on the line if all has been surveyed correctly, bearing in mind some aircraft equipment, ground based aids and pilots may not be entirely accurate depending on whats around.

[LongLats]

BS

I did that one day at EN and the controller said, I dont' know what sort of approaches you do out where you come from old boy, but we have rules and procedures here.

Jeez Zaz, I certainly didn't mean disregard rules and procedures. God knows what you did that day, but that's not what I meant.

You're obviously going to choose an approach that gets you closer to the ground if the weather is causing you dramas. That's what I mean when I say the aim is to get as low as possible so you can break visual.

I suspect the majority of the world's jet & larger turbo-prop operators might disagree with that philosophy.

Of course, Capt Claret. I presumed the OP isn't flying jets or larger turbo prop aeroplanes, seeing as this is was posted in "The Pacific: General Aviation & Questions".

[Capt Claret]

Did the OP not effectively ask two "questions"?

[Capn Bloggs]

The idea with IF flying when you're approaching an aerodrome, is always trying to find a way to get as low as possible so you can get visual and get on the ground.
A few precious types didn't like that, LatLong! Pity they decided not to quote the rest of what you said:

You're always looking at approach steps, 25nm MSAs, 10nm MSAs and route LSALTs to find a safe way down. Just remember you're only protected by these things if you're on track.

Eminently sensible, IMO. And yes, I assumed LL wasn't talking about an A390-2000 operation...

[LongLats]

A few precious types didn't like that, LatLong! Pity they decided not to quote the rest of what you said

Capn Bloggs I doubt they even read my whole post. Would have been too excited by the prospect of correcting someone :hmm:

[Capt Casper]

I have great doubts about many of the posters on this “Professional Forum”.
Greedo asked a couple of very simple questions.
The answer to both is that if you are within or on the radials defined by the sector, you can descend to the altitude defined by a distance, using the tolerances allowed by the rules applicable to the tracking aid.
Long Lats made a statement – which I believe to be correct (professionally) that “The idea with IF flying when you're approaching an aerodrome, is always trying to find a way to get as low as possible so you can get visual and get on the ground.”, presuming, in my understanding of Long Lats post, it is a routine commercial flight OCTA - (professional).
The ethos of a professional pilot should be safe, legal, efficient, and comfortable for those paying your wages & who, in many cases would prefer not to be in an aeroplane.
Commercial flying is a thinking man’s job, and irrespective of the restrictions imposed by rules and SOP’s, if you want a job into the future, you need to keep a mind’s eye on the payer’s.
Bad weather, rough conditions, behind schedule are all good reasons to get visual & on the ground as safely and efficiently as you can (professionally). If the rules allow a simple straight in approach to the circling minima, with a reasonable expectation that it can be accomplished. I see that as preferable to most instrument approaches (involving sector entries and execution), excluding runway and RNAV straight in approaches where local ambient conditions are favourable at the time.
Local knowledge and aircraft speed is also a big factor. If you are not familiar with a location, an instrument approach is often the best choice. On my home turf, I would use a GPS sector arrival as a preferred approach in some instances as I know it will offer a better chance of visually being able to transition from IFR to VFR because the cues are there to identify points of reference to the circuit, and descend with much more room than a straight in approach, complicated by configuration changes, checklists etc allow. In my location, the difference between the sector approach and the runway approach is 150 feet.