The One to Sixty Rule
The One to Sixty Rule has many practical applications in air navigation. The proper use of this rule enables the pilot to accurately calculate various navigational problems such as:
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.
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):
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:
To determine the time/distance to a station these steps are to be followed. After tuning and identifying the VOR station:
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 -