[1][2] For example, a descent from flight level 350 to sea level would require approximately 35x3=105 nautical miles.
This would have to be adjusted for headwind or tailwind,[1] and also to allow for deceleration time.
Alternatively, David P. Davies gives the rule as 300 feet of descent required for each nautical mile of distance.
[4] This is equivalent to 3.14 nautical miles per 1000 ft of descent.
If exactly 3 nmi are allowed per 1000 ft of descent, the glide path will be 3.14 degrees.