Caution: bearing error could result from coastal refraction.

Coastal Refraction alters the bearings, particularly when bearings are at an oblique angle to the coastline.

However, NDB signals are also affected more by atmospheric conditions, mountainous terrain, coastal refraction and electrical storms, particularly at long range.

Both Jersey and Guernsey have ILS on both ends of their east-west runways, but Alderney only boasts an NDB, giving real-life demonstrations of coastal refraction.

Bearings taken on such stations may be very inaccurate owing to errors caused by coastal refraction and the calibration of the Direction Finder employed may vary considerably due to the wide difference in frequencies used, (i.e. the standard broadcast band spreads over approximately 1060 kHz).