Met Minima applicable to Blackall RW 06:
Parts of unclarity:

Part 1)
The answer reads that we should use the NDB approach minima and not the RNAV approach as the GPS is a TSO 129(a), yet on page 4.8 in the case of Kempsey RW 22 the RNAV approach is used to determine T/off minima. Also, as I understand it from ENR. 1.5.2.1 NOTE 3 and ENR 1.5.8.5.5.3, the TSO can be used for an approach - the only limitation on the TSO 129 would be that you can not use it for planning purposes when considering a DEST alternate minima?

Part 2)
Again in the case of Kempsey, a SI (Straight in) approach's figures have been used to determine the minima (626-3.5), but in the case of Blackall, the circling minima (642 - 2.4) has been used and not the SI approach?

Both questions relate to engine failures after take off in IMC, in OZY and both airports have the same choices of RNAV approaches

So to sum it up, why not use the GPS at Blackall, and why not use the straight in approach minima?

Tx, this one has got me confounded.

There is no reason why you cannot do an approach using a TSO 129 GPS. However if you do there must always be another ground based procedure available. See AIP GEN 1.5 page 18.



If you depart with weather conditions below the minima for the ground based aid, you could not claim that it is 'available'. Therefore you cannot take-off unless the conditions are equal to what is required for the ground based approach. That doesn't mean that you can not fly the GPS approach when you get back, but the conditions must allow you to do the ground based approach if it became necessary.

I don't know how old your book is, but the answer to Question 17 on page 4.14 is now 602 ft and 3.4 km vis [the straight in minima].

Also on page 4.8 the text goes on to say that you can fly the GPS approach providing your GPS is a 145 or 146 TSO.
If that is the case, you don't need a ground based aid.



Bob

Hi Bob,

Sorry my previous message must have seemed a bit abrupt - the first portion did not post - don't know why.

In essence I was trying to understand the difference between the questions on page 4.7 / 4.8 (Straight in approach, GPS) "KEMPSEY"; and another question on page 4.14 (answer on page 4.17) "BLACKALL."

In both cases OZY with a TSO129 is used, and in both cases the AD's have both a NDB and a RNAV. In the case of KEMPSEY the departure minima was taken to be the RNAVS Straight In approach, in contrast to the "BLACKALL" scenario where the NDB was used.

However, I believe you hit the nail on the head when you said that the confusion appear to be in the date of my book (July 2011 / purchased 21012), as the reference to page 4.8 doesn't include "Provided you have a TSO145 / 6", and the minima in the BLACKALL question is 642' and 2.4 km's, which happens to coincide with the present DAPs circling Minima, hence my confusion......

I had purchased both you CPL Airlaw and AHUF books with the online version, and it is really the way to go!!! Will definitely do so for my ATP Airlaw - I can appreciate the frustrations caused by continually changing rules and regulations!!!

Just for my peace of mind, am I correct in saying:

(a) There is nothing wrong with using the TSO129 for the ACTUAL procedure, BUT it cannot be used in determining the Destinations AS WELL as Take Off minima. So in effect for ALL minima planning purposes a TSO129 has "no value" on the ground.

(b) Can one always use the Straight In approaches minima, (?provided you know that that particular runway is in use?)

Thank you Bob.

Now you're cooking on gas!

It is a very common point of confusion with students. There is no difference in accuracy between the 129 and 145/6 GPS. When you do an approach with a 129 it is just as accurate as a 145/6 GPS. The only difference is the reliability. If you use a 129 you must ALWAYS have another means of doing an approach. That applies for flight planning to a destination as well as contingency planning for the possibility of an engine failure.

Students often end up believing that you can never do an approach with a 129. That's not correct. Of course you can do an RNAV/GNSS approach with a 129, but it can never be your only means of safely landing.

I must admit that it does seem rather strange that you are allowed to trust a 20 year old ADF but you are not allowed to trust a 129 GPS. However them's the rules.......

And yes, you can use the straight-in approach minima assuming that the runway you used for departure will be available for a return to land if it becomes necessary. Makes sense doesn't it?

Bob