Originally Posted by mathy
6nm up and a ground distance of 12nm? That's a cone with a half-angle of 63 degrees at the apex. Or to put it another way 12nm out in 4800nm travelled is 0.25%
I'm with
mathy here. I think that
Airspeedintervention is simply having trouble judging distance along the ground, when compared to teh map data in the aircraft.
As a "rule of thumb", as something disappears from view under the nose, it is one mile away for every thousand feet of altitude - so cruising at F380, something on the ground disappearing under the nose is 38 miles away. 12 miles is nothing at high altitudes.