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measuring on GPWT, PCA etc

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adambernhardt created the topic: measuring on GPWT, PCA etc

After several email back and forths with Mr Exam master at our regulatory agency, following a pathetic result in my met exam, i have identified the issue thats going to haunt me.

Scenario:
Traveling from Aerodrome A to B have to cross 3 GPWT boxes. Which are irrelevant for this however i will state the location of Point B was so close the GPWT box line that it's almost impossible to confirm based on only using Lat and Long .

I used the PCA to confirm location but that still allows an element of error based on 1) the poor resolution of the GPWT images and 2) inability to use the BOM published GPWT reference cards.

My question is, has anyone figured about best way to measure the 1.5 degrees on the GPWT boxes or PCA for better accuracy?

Getting as close as I could and doing the line clearly wasnt accurate as i expect i blew the 4 GPWT questions which were 8 marks and had i got them would not be faced with 1 more go before a lock out.

If you're unsure of what the reference card is and how simple the exercise would be if IN FACT is was PERMITTED, have attached the GPWT and corresponding card for one GPWT as an example. Note these were NOT the ones on the exam.

Any assistance would be great.
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Stuart Tait replied the topic: measuring on GPWT, PCA etc

G'day Adam

To say I feel your pain is a understatement, could I ask how you interpolate the data when your track is not passing through the middle of the grid, as in do you take in to account the adjoining grids and average or do you have a different method?

Cheers
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adambernhardt replied the topic: measuring on GPWT, PCA etc

i have no idea. Its like 'best guess' no way can i get the accuracy he wants when an aerodrome is literally a pen tip from the line!
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bobtait replied the topic: measuring on GPWT, PCA etc

I have been trying to find an appropriate adjective to describe the GPWT nonsense but I can't find one that can be put into print. To be fair, it's the invention of BOM, not CASA. But you would expect that CASA would be a bit more realistic when it comes to writing exam questions based on interpretation of the ridiculous GWPT charts.

I have yet to meet anybody who has worked out how to use them in practice. Thank God for the flight planning software that is used almost exclusively in the 'real world'. I look forward to CASA publishing a CAAP that demonstrates how they can be used in practice.

The sad truth is that you must go through the process of interpolating between the centre-grid points and converting pressure heights to altitude based on the QNH of the moment, then allow for the heights, at whole thousands, to be adjusted to the VFR cruising levels at whole thousands + 500ft.

When all is said and done, the whole thing is based on a computer model which is probably not entirely accurate anyway!
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adambernhardt replied the topic: measuring on GPWT, PCA etc

Thanks Bob. If we could use the reference cards it would reasonable. Thinking of a letter to the Ombudsman on this whole exam debacle issue to be honest
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