On Sun, 15 May 2005 at 09:05:01 in message
, RST Engineering
wrote:
And a screw-up on the equation:

Radio horizon (in miles) equals the square root of [TWO TIMES the aircraft
altitude above the VOR (in feet)].

[1] Jim, Doesn't that assume that the number of feet in a mile is
the same as the radius of the earth in miles?

The formula for the tangential horizon distance is

[2] d=(2*r*h + h^2)^0.5

where d is the tangential horizon distance, r is the radius of the earth
and h is the height of the object above the surface. DKr and h all in
the same units. Because the heights we are talking about are small
compared to the radius of the earth the h^2 term can be ignored leaving
what you said.

E&OE :-)
--
David CL Francis