W; and "high" at more than 2,000 W.

There are four types of non-directional beacons in the aeronautical navigation service:

* En route NDBs, used to mark airways
* Approach NDBs
* Localizer beacons
* Locator beacons

The last two types are used in conjunction with an instrument landing system (ILS).

Automatic direction finder equipment

NDB navigation consists of two parts -- the automatic direction finder