b Navigation: Very High Frequency Omnidirectional Range (VOR), Tactical Air Navigation (TACAN), Automatic Direction Finder (ADF), Distance Measuring Equipment (DME), Instrument Landing System (ILS), Markers (MKR), Omega, Very Low Frequency (VLF), Inertial Navigation Systems (INS), Inertial Reference Systems (IRS), Satellite Navigation (SATNAV), Low Range Radio Altimeter (LRRA).