N  NPIAS —national plan of integrated airport systems  NR —number  NRC —non-recurring charge  NRCS —national radio communications systems  NSAP —National Service Assurance Plan  NSRCATN —National Strategy to Reduce Congestion on  America’s Transportation Network  NSSFC —National Severe Storms Forecast Center  NSSL —National Severe Storms Laboratory, Norman, OK  NSWRH —NWS Regional Headquarters  NTAP —Notices To Airmen Publication  NTP —National Transportation Policy  NTSB —National Transportation Safety Board  NTZ —no transgression zone  NW —northwest  NWS —National Weather Service  NWSR —NWS weather excluding NXRD  NXRD —advanced weather radar system  OAG —official airline guide  OALT —operational acceptable level of traffic  OAW —off-airway weather station  OBSC —obscured  OBST —obstruction  ODAL —omnidirectional approach lighting system  ODAPS —oceanic display and processing station  OEP —operational evolution plan/partnership  OFA —object free area  OFDPS —offshore flight data processing system  OFT —outer fix time  OFZ —obstacle free zone  OM —outer marker  OMB —Office Of Management and Budget  ONER —Oceanic Navigational Error Report  OPLT —operational acceptable level of traffic  OPR —operate  OPS —operation  OPSW —operational switch  OPX —off premises exchange  ORD —operational readiness demonstration  ORIG —original  OTR —oceanic transition route  OTS —out of service; organized track system  OVR —over  PABX —private automated branch exchange  PAD —packet assembler/disassembler  PAEW —personnel and equipment working  PAM —peripheral adapter module  PAPI —precision approach path indicator  PAR —precision approach radar; preferential arrival route  N —north  NA —not authorized  NAAQS —national ambient air quality standards  NADA —ADIN concentrator  NADIN —National Airspace Data Interchange Network  NADSW —NADIN switches  NAILS —National Airspace Integrated Logistics Support  NAMS —NADIN IA  NAPRS —National Airspace Performance Reporting System  NAS —National Airspace System or Naval Air Station  NASDC —National Aviation Safety Data  NASP —National Airspace System Plan  NASPAC —National Airspace System Performance Analysis  Capability  NATCO —National Communications Switching Center  NAV —navigation  NAVAID —navigation aid  NAVMN —navigation monitor and control  NAWAU —National Aviation Weather Advisory Unit  NAWPF —National Aviation Weather Processing Facility  NB —northbound  NCAR —National Center for Atmospheric Research,  Boulder, CO  NCF —National Control Facility  NCIU —NEXRAD Communications Interface Unit  NCP —noise compatibility program  NCS —national communications system  NDB —non-directional radio beacon  NDNB —NADIN II  NE —northeast  NEM —noise exposure map  NEPA —National Environmental Policy Act  NEXRAD —next generation weather radar  NFAX —National Facsimile Service  NFDC —National Flight Data Center  NFIS —NAS Facilities Information System  NGT —night  NI —network interface  NICS —national interfacility communications system  NM —nautical mile(s)  NMAC —near mid-air collision  NMC —National Meteorological Center  NMCE —network monitoring and control equipment  NMCS —network monitoring and control system  NMR —nautical mile radius  NOAA —National Oceanic and Atmospheric Administration  NOC —notice of completion  NONSTD —nonstandard  NOPT —no procedure turn required  NOTAM —notice to airmen  NPDES —National pollutant discharge elimination system  NPE —non-primary airport entitlement  B-8  O  P 