When the known ground speed, or estimated ground speed, is placed over the RATE
INDEX (60 minute mark) on the computer, any given distance on the outer (DISTANCE)
scale will match with the correct time on the inner (TIME) scale. The distance flown, or the
time it will take to fly a given distance in any given time, will be easily determined.
NOTE: It is often necessary to convert from decimal minutes to minutes and seconds (or
vice-versa). Table 4.3-1 shows the conversion. This table also applies to decimal hours
and minutes as well.
How long will it take to fly 350 NM at a ground speed of 150 kts?
Estimate the answer. In two hours, 300 nm will be flown (150 x 2); so, it will take
slightly over 2 hours (120 minutes).
Set the ground speed of 150 knots over the RATE INDEX (60 minutes) on the TIME
scale. (Figure 4.3-16)
Figure 4.3-16 Time 1