Due to our 10th Anniversary of Geocaching in October 2012 we are making a Series of Slovenian VOR/DME caches. First in this Series is ILB (In communications it is INDIA LIMA BRAVO) VOR/DME station located near Ilirska Bistrica.
If you are interested just in quick found cache stop reading now! And go for cache hunting. 
Picture of VOR/DME station
If you are interested what the VOR/DME stations are, read further!
Near cache location you will see two buildings with the names: ILB VOR and ILB DME. No high fences, security cameras. Just a sing with the logo of Slovenia Control - the company responsible for managing Slovenian air traffic. The "code name" VOR/DME ILB short for VHF Omnidirectional Radio range with Distance Measuring Equipment. It is a radio beacon. It comes from the 1950 era where there was no GPS sistem. From 2000 when president Clinton turned off SA GPS system became more used in airtraffice navigation too. Like in Geocaching :)
Airplane pilots are usually not relying on GPS signals for determinating their position but on measurements based on radio signals sent from ground stations. These stations are commonly referred to as navigational aids, short "navaids". There are basically two different types of ground stations used for this purpose. VORs are used for determining directiions from or to VOR statiions, DMEs are used for determining distance from DME stations. With VOR and DME a single ground station is enough for position determination.
On the left is schematics of an Airplane flying from VOR station. On the right there is VOR instrument in the Airplane.
Airplanes are using their own navigation charts where VOR/DME stations are used as IMPORTANT Crossings.
On the lower left part is VOR/DME named ILB - Bistrica.
For better understanding of importance VOR/DME stations there is detail of ILB VOR/DME. Each VOR/DME station is described with name (Bistrica), frequency (114.80), sign(ILB), morse coded sign (.. ._.. _...) and GPS position (N45 33 56 E014 10 15)
In Slovenia there are 4 VOR/DME stations. And ILB is the first one in this series!