In the equation W = 2 x d x tan(DF error angle), what does d represent?

In the equation W = 2 x d x tan(DF error angle), what does d represent?

• A. Line of sight distance in Nautical Miles
• B. Width
• C. DF error angle
• D. Antenna height

Answer: (A)

The distance d is the line-of-sight distance to the target. In this formula, W represents the lateral width of the uncertainty caused by the bearing error, so the width grows with distance and with the size of the angular error. The two sides of the uncertainty cone on either side of the true bearing give W = 2 d tan(DF error angle), which is why d must be a distance, not a width, angle, or height. In navigation terms, using line-of-sight distance in nautical miles keeps W in the same units (nautical miles) and shows why a larger distance magnifies the footprint of the DF error. The other quantities listed—width, the angular error itself, or antenna height—do not fit this relationship.

The distance d is the line-of-sight distance to the target. In this formula, W represents the lateral width of the uncertainty caused by the bearing error, so the width grows with distance and with the size of the angular error. The two sides of the uncertainty cone on either side of the true bearing give W = 2 d tan(DF error angle), which is why d must be a distance, not a width, angle, or height. In navigation terms, using line-of-sight distance in nautical miles keeps W in the same units (nautical miles) and shows why a larger distance magnifies the footprint of the DF error. The other quantities listed—width, the angular error itself, or antenna height—do not fit this relationship.