I'm trying to come up with the D&D 3.5e world's functional equivalent to a real life Non-Directional Beacon (NDB).
Are there any existing spells in D&D 3.5e that can be cast on durable objects (say, stone monoliths) to make them into some sort of beacon that can be homed upon (or better yet, used for direction-finding purposes) from a long distance (miles, not feet) by some other means than sight (say, with the aid of a spell or magic item used or carried by whoever desires to home in on it)? Magic items are welcome instead, provided they are durable enough to survive being placed outdoors!
Source material is unrestricted save for epic level spells (a straight Wiz20, Clr20, or Drd20 should be able to make a beacon). It should cost less than constructing an inn or other permanent structure, and should not require special jewels or other exotic materials in the monolith itself. However, if the homing/direction-finding function can work over the many miles required, then the range of imbuing the object does not matter -- it's not a major problem if a touch-range spell requiring several hours of work is needed to set one of these up, as the beacon-monoliths are set-and-forget. The homing function itself, though, must be available cheaply (as a first or second level spell if not a cantrip or orison for divine casters; bonus points if it's available as an arcane spell as well); a permanent magic item is acceptable instead provided it is not bound to a specific instance of one of these beacons, small enough for a user or their mount to wear, and costs less than oh, say, 10,000gp.
Custom magic item research should not be a problem, nor is custom spell research. Houserules can be proposed here -- I'm workshopping this here because I don't know how to translate what I want from the RL terms I understand it in to something a DM who is utterly unfamiliar with the real-life IFR environs can understand.
Also, teleportation itself isn't workable (teleport isn't accessible enough, and probably has too short of a distance, besides, this needs to work on a day-in-day-out basis), and find the path may not work so well in an aerial environment (can you set up a holding fix with it?). The same accessibility argument holds for Plane Shift...