Figure 1-11 Ten Percent (10%) Method

CHAPTER ONE

LOW-LEVEL AND TACTICAL FORMATION

1 minute. This also means you can gain or lose 6 seconds for every minute the

adjustment is made (Figure 1-11).

Time ahead

Time to hold

or behind

speed change

(seconds)

(minutes)

Figure 1-11 Ten Percent (10%) Method

iv.

Incremental Method. To determine the increment, first find your groundspeed

in nautical miles per minute (180 kts = 3.0 miles per minute). Multiply this by

10 to get the increment (3.0 x 10 = 30). Divide your time ahead or behind (in

seconds) by 10 to determine the number of minutes to hold the correction. For

example, if you are 50 seconds late, you must hold the 30-kt correction

(increment) for 5 minutes (50 sec/10). Note that you will gain or lose 10

seconds for every minute that you hold the increment (Figure 1-12).

Try to have your overall timing corrections accomplished by the time you arrive at the IP.

Likewise, when back on time, analyze why you got off time. Also check that you are now

maintaining the correct or new IAS (if one was required).

NOTE

If you are close to continuation fuel, beware of increasing your

speed too much. The increase in fuel consumption may force an

early return to base. In this situation, it may be better to accept and

allow the timing error.

1-26 LOW-LEVEL NAVIGATION