Ground/Air Nautical Miles

David CL Francis wrote in message ...
On Wed, 3 Nov 2004 at 12:33:39 in message
.net, John T Lowry
wrote:
A trip of 100 nm over the ground, in an hour, if into a 10 knot direct
headwind, would be a trip of 110 nm relative to still air.

Are you sure about that?
Aircraft flying at 200k effective speed over the ground 190 knots
agreed?
Time taken = 100/190 = 0.5263157 hours
Effective distance at 200k TAS is 200*0.5263157 = 105 .26 nm

I'm no expert, but I think you misread and overanalyzed his statement
grin.

He said the 100nm trip was actually made in 1 hour while into a 10kt
headwind. Therefore the effective speed was 110kts, and the effective
distance (which is the point of ANM) was 110nm in that 1 hour.

ANM is sometimes used to compute the theoretical range of an aircraft.
For example, you fly a prototype jumbo jet from NYC to Paris, and it
took X thousand pounds of fuel. But after you add in the headwind x
time, then you can figure out the total ANM that it it went, and thus
compute its range or fuel usage/nm.

Kev