Paper Plotting 1 ....... Page 14 of 37
To determine the time of CPA, put the divider points on R and M.
We know R to M represents the distance the echo trail traveled in 6 minutes so walk your divider down the Relative Motion line adding 6 minutes each step.
Rarely does a divider point land right on the CPA so "eyeball" the distance and add your estimate to the latest total.
We could do the math and be more accurate, but these eyeball estimates are close enough for exam purposes.
