A quick search on PPrune archives reveals this for reciprocal tracks and more.....
zkjaws
5th May 2009, 09:40
There is a simple formula to work out the Estimated Time of Passing (ETP)
ETP = ETO1 + EET1 (ETO2 - ETO1)
EET1 + EET2
EET = Estimated Elapse Time between two points
ETO = Estimated Time Over one point
It can be found on a pray wheel (nav computer) by:
Set EET1 + EET2 on the outer scale over EET1 on the inner scale;
Opposite ETO2 - ETO1 on the outer scale read X on the inner scale
Add X to ETO1 = ETP
Last edited by qwerty2; 3rd October 2012 at 13:05.