Wind Side - P-12820247

T-45C TS INav-08

Fuel, Weather, and Alternate Airfield Planning

WIND SIDE

The primary use of the Wind Side of the Air Navigation Computer is to calculate the forecast ground

speed, which of course is utilized to determine time enroute and fuel required for each leg of the flight.

Another important use is a point-to-point calculation to determine a course and distance from destination

Initial Approach Fix (IAF) to the alternate Initial Approach Fix.

To solve these problems on any model of the circular computer consists of a simple arrangement for

setting up vector triangles.

The Wind Triangle

The wind triangle consists of:

The Wind Vector, made up of wind direction and velocity. Plotted on the wind

side starting at the grommet in the direction of the wind, its length represents

the velocity. On a plotting board it would be a solid line with three

arrowheads.

The “AIR” vector, comprised of the TRUE heading (TH) and the TRUE airspeed (TAS).

The air vector always ends at the beginning of the wind vector (the grommet on the

computer) and represents the path assuming no wind. On a plotting board it would be

depicted as a dashed line, with a single arrowhead.

The “GROUND” vector is made up of COURSE (CUS) and

GROUND SPEED (GS) and represents the path of the aircraft

caused by the wind. Its origin is the same as the air vector, and

ends at the head of the wind vector (or wind dot). On a plotting

board it would be depicted as a solid line, with a single arrowhead.

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