This will yield an answer in hours minus a number (A hours - B/C).
It will not yield a distance
Keith, I have corrected my CP formula (I had a "-" where I should have had an "x"). Hopefully this gets rid of the confusion of having a denominator in nm/hr (i.e. the hr unit) but that fraction shouldn't matter as the number will still be correct (i.e. nm/hr is always expressed as nm per (1) hour and anything divided by 1 is going to equal the numerator although technically yes there is another dimension added to the mix). If we stick with the convention of using knots (which shows no fractions other then the assumed 'per nm') the formula will yield a distance.
This thread is incredibly convoluted for a very very simply matter. The formulae below are correct:
PNR = (Flight Fuel - Extra Fuel Burnt on Climb) / (SGR Home + SGR Continue)
Dist to CP = (Total Distance - GS Return) / (GS Home + GS Continue)
Nil wind example (TAS = 250 knots, Distance 500 nm)
Dist to CP = (500 nm x 250 knots) / (250 knots + 250 knots) = 250 nm
Head wind example (TAS = 250 knots, Distance 500 nm, Headwind 25 knots)
Dist to CP = (500 nm x 275 knots) / (275 knots + 225 knots) = 275 nm
Tail wind example (TAS = 250 knots, Distance 500 nm, Tailwind 25 knots)
Dist to CP = (500 nm x 225 knots) / (225 knots + 275 knots) = 225 nm
For those playing the game in Aus have a look at
this post which gives a way to extract the formula from the ATPL texts allowed in the exams (ie the 727 manual). (That, by the way is why I chose the wording I chose such as "home" and "return" which are, of course, intended to be the same thing.)
I like "DHOH" and will look at making the transition.
