What factor minimizes coastal error for an ADF bearing?

Minimizing coastal error for an ADF (Automatic Direction Finder) bearing is best achieved by crossing the coast perpendicularly. When an aircraft approaches the coast at an angle, the signal received can be distorted by the differing wave patterns, reflections, or terrain features found at the coastline. However, if the aircraft crosses directly over the coast (perpendicularly), it reduces the potential for ambiguity caused by the transition from water to land, allowing for a more accurate bearing.

The perpendicularly crossing of the coast enables a clearer, more distinct signal correlation from the ADF, minimizing the effects of coastal interference and potential multipath reception. This strategy optimizes the reliability of the ADF readings, ensuring better navigational accuracy during critical phases of flight, particularly in approaches or departures near coastal areas. In contrast, other factors such as distance from the coast, the type of ADF receiver, and flight altitude do not provide the same level of error mitigation for coastal influences on ADF bearings.