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Old August 23rd 10, 03:10 AM posted to rec.aviation.soaring
akiley
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Posts: 114
Default required LD versus required MC to make it home ??

Hi All,

I'm aware of and use the math formula to get my rental Cirrus back to
home base, but I like to back it up with SeeYou mobile. I know it's
recommended to use required LD to target making sure you have entered
a correct polar and safety altitude. But this doesn't account for
winds does it? If you are flying away from your target wondering how
far you can safely fly, you can't depend on required LD because big
headwinds can make this number useless. As an example, I notice I've
got 25LD required to my home base. I turn around and because of the
headwinds, I can only make 18LC. Outlanding anyone.

I'm curious about MC required to target. Wouldn't that be better to
use if you make sure all data is correct such as polar, winds, safety
altitude and make sure the correct target is activated. This way, I
can wander away from my home field and I know if my MC doesn't fall
below about say 7 (which plays out to about 20 LD in no wind) I am
fairly assured of making it and that this MC will be wind aware. Of
course it can't know about hitting lots of sink, but it seems a better
way for my type of non task, local soaring.

Before I finish, I would like to note that the MC to target NavBox in
SeeYouM doesn't always update very quickly if you change the winds
aloft manually. For this problem, I scroll the MC value untill the
little glide slope type indicater on the left side of SeeYou centers,
then compare that MC to the required MC NavBox.

akiley