1. Topic 2.1 Extended H – Relative velocity – plotting courses
FYI: A nautical mile is 6076 ft (compared to the commonly used statute mile of 5280 ft).
Topic 2.1 Extended H – Relative velocity – plotting courses
Wisconsin Aeronautical Charts (WACs) are used by pilots to navigate from one airport in Wisconsin to another.
Among the many things shown on the WACs are Maximum Elevation Figures (MEFs), obstructions, beacons, radio call signs, etc.
Suppose we want to fly from Milwaukee Mitchell, to Hartford Airport.
© 2006 By Timothy K. Lund
Suppose that the wind is blowing at 22 knots (22 nautical miles per hour) out of the west.
Suppose further that your Cessna is capable of an airspeed of 100 knots.
In what direction should you head your Cessna, and how long will it take to reach Hartford Airport?

2. NORTH / SOUTH REFERENCE
FYI: Pilots measure angles WRT NORTH. In other words, North is 0°.
FYI: Always measure angles WRT PARALLELS or MERIDIANS.
ORIGIN: Milwaukee Mitchell
DESTINATION: Hartford Airport
WIND: 22 kn from west
AIRSPEED: 100 kn
N = 0°
VAG
Bearing is 308°.
Groundspeed is 83 knots.
vPA + vAG = vPG
plane equation
Distance is 32.5 nm.
MERIDIAN OF LONGITUDE
NORTH / SOUTH REFERENCE
Time is 23 minutes.
VPG
VPA
© 2006 By Timothy K. Lund
E = 90°
W = 270°
PARALLEL OF LATITUDE
EAST / WEST REFERENCE
S = 180°
The wind, and the destination's bearing.
Step 1: Draw a line through ORIGIN and DESTINATION.
Step 2: With your plotter, draw a scale WIND (VAG):
Use any scale you like, but END it at DESTINATION.
Line up plotter on course.
STEP 5: Find BEARING of VPA:
Step 3: With SAME scale, draw VPA:
There are two directions we have no control over:
STEP 4: Draw in VPG:
It must END on the Tail if the WIND VECTOR.
It must BEGIN on the ORIGINAL LINE (the red one).
Find ACTUAL DISTANCE between ORIGIN and DESTINATION:
Place bull's eye on a meridian.
Bearing should be between 270° and 360°.
Find the magnitude of VPG using SAME SCALE:
Be sure to use CORRECT SCALE FOR MAP:
Now we can calculate the travel time: t = d/VPG...