Figure 4.3-20 Speed 1

SPEED

If time and distance are known, simply transfer the ratio, or proportion, information to the

DISTANCE and TIME scales of the CR-3 computer and read the unknown factor of speed

over the rate index. Use the same formula previously discussed:

SPEED

DISTANCE

RATE INDEX

TIME

EXAMPLE

Given:

Distance covered. . . . . 30 NM

Time flown . . . . . . . . . .11 min

Find:

Ground Speed

Solution:

Estimate the answer. 11 goes into 60 approximately 6 times, so the speed is

approximately 6 x 30 or 180 kts.

Xnm =

30nm

60min

11min

Locate the distance (30 NM) on the outer (DISTANCE) scale and place the time

flown (11 minutes) directly under the distance on the inner (TIME) scale. (Figure 4.3-

20)

Figure 4.3-20 Speed 1

4.6-67