Hi N1,
Our operation prefers to use the 3 degree glide slope rule:
- Where to start the descent?
For every 1000' you need to lose add 3 miles. So F140 - F40 = 10 x 3 = 30nm. You may want to add 5 - 10 nm as a precaution (ATC speed restrictions etc...) to avoid arriving high or having to use an unneccessarily high RoD.
RoD required
- Ground speed/2 + a 0 = 250kts (assuming this is your groundspeed and not IAS)/2 x 10 = 1250' FPM.
- Monitor your height v distance to go all the way down and change accordingly.
Simples
