PPRuNe Forums - GNSS approach waypoints

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GNSS approach waypoints

Hi folks,
I've been looking at the coded waypoints on GNSS-Z approaches and can only figure out a few of the meanings. ie I can figure which is initial, final and missed approach points.
I've googled this subject but not with much luck. Can anyone suggest a reference that describes how each waypoint is named and what the different letters stand for?
Thanks

Hi framer,

The easiest way is to display MAP in PLAN and examine the track and distance between each way point. The MAP will centre on the from way point.

Where in the world and which service provider?

There are a number of different naming conventons used. It depends on what the local CAA dictates.

In N. America they just use unique 5 character names obtained through the ICAO ICARD database.

But in Australia for example they use a site based 5 character process. The first 3 are the site ID. The next character represents the direction from which the approach starts (i.e. "E" if from the East, "N" from the North). The character is for the specific waypoint. The initials are A, B, or C. The intermediate is I, and the Final F. The missed approach waypoint uses M, and the holding waypoint uses H. So CLQEA would be the Cape Leveque East (Rwy 31) initial (Right) approach waypoint. The missed approach waypoint is CLQEM, and missed approach holding is CLQEH.

Clear as mud?

Hey Direct,
that was a bloody informative post for your first crack, Nice work! It does make things a lot clearer for me. I pop down to Australia once or twice a month and it was a Melbourne approach I was trying to work out. After what you've told me I can just about read it like a normal approach instead of a sea of letters , Ta .
PS I would still be interested in reading a bit more about Ausi GNSS approachs if anyone has a reference to a website or PDF.
Thanks again, Framer

It sure did thanks Hoppy, I'l paste it below for future readers.
Have a good one :)

Quote:

In general, waypoint names use the first three letters to
identify the aerodrome, the next letter to identify the compass
quadrant from which the approach is flown, and the final
letter for the approach waypoint. As an example, the
Runway 24 GPS approach for Paraburdoo, WA (YPBO) uses
“PBO” as the first three letters, and “E” as the fourth letter, of
all waypoints. The various waypoints are identified as
follows:

•

The initial approach waypoints (usually a selection of three)
allow flying of the approach without use of a sector entry
procedure. The initial points mark the start of the approach
and are usually designated with “A”, “B” and “C” as the fifth
letter of the waypoint name.

•

The intermediate waypoint achieves alignment with the final
approach course and has “I” as its fifth letter.

•

The final approach waypoint marks the point where the
receiver has completed transition to the approach mode (CDI
scale and RAIM tolerance goes to 0.3nm) and has the “F”
designator.

•

The missed approach waypoint is normally at the runway
threshold and is designated with the letter “M”. The missed
approach mode must be manually selected for the receiver to
give missed approach tracking information. On selection, the
receiver CDI scale and RAIM tolerance reverts to 1.0nm.

•

A missed approach turning waypoint, if required, is designated
with the letter “T”.

•

The missed approach holding waypoint is designated with the
letter “H” and used to provide tracking for the missed
approach.

The exception to this rule is that initial approach fixes may be
given a pronounceable five letter name when they are located

at the terminating waypoint of a STAR.

I assume, Framer, you are studying for your GPS NPA endorsement! :}

Sanity appears to have prevailed in Oz: RNAV GNSS waypoints are now coming out using the IATA airport code instead of the last three letters of the ICAO code. "PADSI" may eventually become "ADLSI", as at Gladstone: GLT is used instead of YGLA. Or am I reading too much into it??

Quote:

I assume, Framer, you are studying for your GPS NPA endorsement! http://images.ibsrv.net/ibsrv/res/sr...s/badteeth.gif

heh heh nah, it's something that I really should have known for years but has slipped through the gaps in my study. We very rarely (I think once in the last 24 months) use a GNSS approach. The only time I've done it is either in the sim or a practice one on a beaut day when there's no traffic flow issues.
Pprune is a great resource sometimes. I was having a quick look at Melbourne yesterday morning because I'm going there next week and when I came across the GNSS chart it annoyed me how non-sensical the waypoints seem. It particularly annoys me how they do several count downs to 0nm on final. It really does reduce my S.A. because it interferes with the three times profile that I've been doing for the last ten years on every other approach. That said it's fine if you plan for it.
Anyway, pprune provided exactly what I was after while I was having a mid afternoon nap. brilliant!
Cheers

Quote:

it annoyed me how non-sensical the waypoints seem. It particularly annoys me how they do several count downs to 0nm on final.

Agree and Agree.