GFT for PPL -formulae used during Diversion.
Hi,
Are you referring to the diversion part of the Nav for the GFT for a PPL? If so -please read on... if not ignore it.
I recall using the simple formula that
Max drift = 1/2 wind velocity.
So if the Wind was 12 Kts -drift would be 6 degrees.
ETA for arriving at a destination was calculated by:-
Time =2/3Dist + or - 10%.
Where the + or - refers to a headwind or tailwind.
So for example, you measured a diversion distance of approx 21 miles.
To get this distance you could have used a ruler or your thumb(=10 nm on 1:500,000 chart).
Time=2/3*21=14 mins.
Now suppose your flying into a headwind therefore add 1.4 mins.
So approx time= 14+1.4=16 mins. approx.
For tailwind -you need to subtract. So time to ETA would be approx 13 mins.
These worked for me during diversion practices for the GFT test and the test itself.
Best of Luck.
Has.