Recurrent flight inspection in an aeropearl king air to validate the coverage and accuracy of the aid
-Redundancy of equipment, backup power supplies etc
-Lease of land for the facility
-Cost of periodic maintenance for instrument approach procedures using the aid
Some of this is just a belt & braces approach that is gold plating the system and serving to help build empires within AsA.
AsA charge multiples of what other agencies around the world charge for the same service. The US can install ILS on a runway for about 1/7th the cost of AsA. Why?
I can't find a reference for the maintenance cost of NDB's, but modern NDB's require a building about the size of a phonebox and have centralised monitoring capability.
The FAA are continuing to operate but cease flight testing of many NDB's. Why wouldn't AsA consider this?