Navigation (CRP5 Wind/GS etc.)

[Avyator]

I'm just wondering if there is any rule that tells when to use wind down or up method. On some of the questions from Bristol QB I need to use wind up method to get the correct answer. The problem is then to decide which answer that is correct, because the wind down answer is an alternative as well...

[GgW]

Wind down or wind up method, should give you the same answer. Its a matter of personal choice which method you like to use. In general the wind down method is taugh by most school's.

[Avyator]

That's what I thought, but I still get two different answers.

Here is the question:
An aeroplane is flying at TAS 180 kt on a track of 090. The W/V is 045 / 50kt. How far can the aeroplane fly out from its base and return in one hour?

Need to use the formula PSR = E x H / (O + H).

If I use wind down method to get my groundspeeds to put into that formula above, then I get 88NM. If I use wind up method groundspeeds, then I get 85NM.

Anyone get the correct answer with wind down? (85NM).

[Phenom100]

Wind Down i get 85NM.

[nmcpilot]

Just use an electric flight computer, unless it is for JAA ATPL's where you have to use a CRP5. I mean c'mon analogue computers? It isn't 1945 anymore!

My CRP 5 broke after ATPL ground school, it was cheaper to buy an electric one rather than the whizwheel, Jeppesen also do an electric one which you can clip onto your kneeboard which seems like it would be useful.

They both get the same answers you just don't have to spend a week learning how to use an electric one.

[gmac1977]

Secret!

Wind arms, wind arms, wind arms!