A common example is pushing the "Direct" button, entering a destination and seeing the device pop up the on-course heading, the current ETA and a great-circle route
overlaid on a moving map.
Recalling some long-mothballed NATOPS knowledge, we knew that the waypoint-couple option calculated a great-circle route
. This route was more direct and more fuel-efficient than flying a heading-direct profile, especially over the 1,100 miles we had yet to fly.
Another basic calculation for the distance (d) from a geo-point (P) to a great-circle route
(A-B) can be obtained using the similar algorithms (McGovern, 2004; Ersts, Horning, & Polin, 2009) as depicted in Figure 2.
Details for the selected aircraft appear in a table complete with the registration number, aircraft type, country of origin, the great-circle route
for the flight--the list goes on.
The other 17 degrees came from the vagaries of computing a great-circle route
. That is, a straight line on a curved earth isn't straight the same way we like to think about it on a map.
Think in terms of the most direct path (great-circle route
) from the Moon to the Sun.
The next chapters cover the pioneering great-circle routes
from North America to Europe and to the Orient.