Under an FAA proposal, certain ILS approaches, localizer-type directional aids (LDA), microwave landing systems (MLS) and nondirectional beacons (NDB) at some 25 U.S. airports would become unmonitored by ATC or FSS facilities due to their low annual activity or the fact they are not authorized for alternate airport filing when the control tower is closed. The cutback is a cost-cutting measure, and it presumably shifts to pilots the burden of reporting signal malfunctions to ATC or FSS facilities. A number of navaids are already unmonitored throughout the National Airspace System. The FAA said unmonitored navaids will be annotated as such on navigational procedure charts. Comments are due Friday.