Mental Dead Reckoning (MDR) off-track corrections

Based on the 1:60 rule:

Angle between the Heading and the track = (XWC (kt) x 60) / TAS (kt)
Angle between the Heading and the track = (12 kt x 60) / 120 kt
Angle between the Heading and the track = 6°

Triangle of Velocities:

When creating the velocity triangle using the provided data, a right-angled triangle is established. This right angle corresponds to the angle formed by the W/V vector and the Ground Speed/True Track vector. If we denote θ as the angle between the Ground Speed/True Track vector and the True Airspeed/True Heading vector, the relationship can be expressed as follows:

sin(θ) = Wind Velocity/True Airspeed = 12/120 = 0.1 ⇒ θ = 5.74° ≈ 6°.

• Wind Correction Angle = 6° (Depending on the crosswind it could either be left or right)

1-in-60 Rule:

Angle between the heading and the track (WCA) = (XWC (kt) x 60) / TAS (kt)
Angle between the heading and the track (WCA) = (12 kt x 60) / 120 kt
Angle between the heading and the track (WCA) = 6°

The WCA is calculated based off of the TAS and not the GS, which is why we have not used the HWC for our calculations. The faster you move through the air (higher TAS), the less the wind pushes you off course and vice versa. This is all relative to the air which is why TAS is used. Using GS wouldn’t account for the aircraft’s interaction with the air correctly.