Thank's Bob

I think it has sunk in ... still a little 'unclear' to me .... must be missing something.
The reason for being so pedantic is that when I did the IREX Exam I had 2 alternate lighting question and KDR indicated I got one of them wrong ...

Regards
David

One more ...

ERSA Page 781 BANKSTOWN ARRIVALS (from the NORTH)

2 options ..

via SGT or via SCO
However, the SCO option indicates at the end that "FL200 and BLW"

Does this mean that if you are "FL200 and BLW" you MUST choose the SCO option

EXTRA: When deciding on alternates (or otherwise) and arrival is at night ..... is it good practice to go straight to the lighting arrangement and if NOT OK then don't worry about the rest ...... is there a problem with this ...

Regards
David

Yes, as it says in the first page of FPR, 'all aircraft are REQUIRED to comply'. So you must plan via that route if you are in CTA.

I see no reason why you shouldn't check the lighting first for night alternate planning. That is often the reason why you need to plan an alternate - so it may save some time.

Bob

Hi Bob

Just to clarify ..

BANKSTOWN ARRIVALS (from North) says ..

Via SGT : SGT W214 RIC DCT BK
Via SCO : SCO W365 RIC DCT BK, FL200 and BLW

So, provided in CTA, and you are FL200 and BLW, you MUST arrive at BK via SCO, is that correct?

ALSO: IREX Book Page 3.51 Question 3 (Narrabri --> Bankstown). All the way from Narrabri to either of SCO OR SGT you are OCTA (ie at A080 and E and C have LL 8500) ... so where does the rule about in CTA kick-in?

Worried ..

Regards
David

You don't have to be in CTA for the entire flight. But your flight will enter CTA and you are arriving from the North. There's nothing special about Narrabri, it just means you are arriving from the north. The controllers want flights arriving from the north to enter CTA from that direction. In a question like this, you are being asked to select the most appropriate answer from the four choices given. It's a bit like VFR entry points for VFR flights.

In many cases you will be radar vectored anyway once you are identified.

Hi Bob

All's going well I think ... I get more concerned about CASA's wording than anything else.

Here's another:

You are undertaking a GPS (with VOR or NDB) arrival. [The arrival could have been DME as per DAP chart].

1. On approach you notice that RAIM warning light comes on ..... can you move immediately to a DME approach OR must you do a MAP and then try a DME (or other) approach.

2. If you are told that RAIM is not available to you (therefore GPS not reliable) .. can you still do the DME arrival?

Regards

David T

A DME/GPS arrival is often referred to as a DGA. It doesn't matter where you get your distance information from. However many GPS arrival procedures are for aerodromes with no DME. In that case you would of course have to do a missed approach. If a DME is available, there is no reason why you couldn't change from the GPS distance infromation to the DME distance information.

Thanks Bob ...

Here's one re Position Fixing (see attached image).
Assuming VOR1 and VOR2 are in 'range' AND there is no DME available, then I assume you CANNOT use these for a Fix as the angle between (extended)lines is less than 45 degrees.

Interesting though ..... if VOR1 had a co-located DME then a FIX can be used using VOR1/DME only AND the angle between these is certainly less than 45 degrees (is zero). I assume this is the exception.
NOTE: Although, if I read the AIP a bit more carefully, it does say that the POSITION LINES cannot intersect at less than 45 degrees ......

Regards
David T

A position line does not have to be straight. A DME arc is still a line. A co-located VOR and DME will continue to give a positive fix while ever you are within the rated coverage. A VOR radial is simply a radius of a circle centred on the VOR and a co-located DME arc provides the segment of a circle centred at the same VOR. These are two position lines cutting at an angle of 90 degrees. According to basic geometry, the radii of a circle cut the circumfrence at an angle of 90 degrees.

If you had a co-located VOR and DME you wouldn't need any other aid to obtain a positive fix.

Thanks Bob ... the DME "arc" as a line makes all the sense.

What about the first bit and the attached image .... am I correct there?

Regards
David