DRIFT CORRECTION

In the following example, an airplane drifted 8 NM after flying 65 NM. Three steps are required to find the wind correction angle needed to arrive at the destination.

Step 1 - The drift in degrees

Solve triangle CAD

8/65=ANGLE/60 or ANGLE=480/65=7.3 Degrees

Step 2 - Correction in degrees to destination

Remaining distance AB - AC = 100-65=35

Solve triangle CBD

8/35=ANGLE/60 or ANGLE=480/35=13.7Degrees

Step 3

Add angle CAD to angle CBD to find heading to fly

7.3+13.7=21 degrees

DISTANCE AND TIME

The formulas for determining time and distance to a station are also derived from the One to Sixty Rule. The distance to a station can be calculated by flying an aircraft perpendicular to a given bearing (or radial) and by noting the elapsed time between bearings. For reasons of convenience, increments of 10 degrees changes in bearings are desired. The One to Sixty proportion is the basis for obtaining the desired formula.

The relationship in (a) is similar to the one shown earlier.

The distance between bearings is a function of the aircraft's speed and the lapsed time. Using basic Algebra leads to the following conclusion (b):

or

Combining (a) and (b) results in the following formula:

Similarly, the time to the station can be calculated using the One to Sixty Rule. The following proportion is derived from the One to Sixty Rule:

or

To determine the time/distance to a station these steps are to be followed. After tuning and identifying the VOR station:

1. Determine the radial on which you are located.
2. Turn inbound and re-center the needle if necessary.
3. Turn 80° right, or left, of the inbound course, rotating the OBS to the nearest 10° increment opposite the direction of turn.
4. Maintain heading. When the CDI centers, note the time.
5. Maintaining the same heading, rotate the OBS 10° in the same direction as in step 3, above.
6. Note the elapsed time when the CDI again centers.
7. Use the formulas shown earlier to determine the Time/distance from the station.

SLOPES

Another practical application of the One to Sixty Rule is estimating the height of a cloud by using the RADAR echoes return. The RADAR antenna is tilted up and down to points where there is no return.
The distance of the cell is given by the RANGE ARCS and the Tilt Angle is derived from the difference between the lowest and the highest echoes.

From the One to Sixty Rule-

It follows that the height of the cloud in Nautical Miles-

The height of the cloud in Feet-

The following approximation is widely used as a rule of thumb -