| 6301 | NTW | Nationwide Airlines (Pty) Ltd. | IATA: CE, Callsign: Nationwide, IATA Prefix: 567, Ceased Opdations on 29 April 2008. Designator CE reinstated by IATA. Name changed from Nationwide Air | ZA | AVCODES |
| 6302 | NTW | Nationwide Air | IATA: CE, Callsign: Nationwide, IATA Prefix: 567, Name changed to Nationwide Airlines (Pty) Ltd. | ZA | AVCODES |
| 6303 | NTW | Maxair, LLC | Callsign: Northwoods, | USA | AVCODES |
| 6304 | NTW | Nationwide Airlines | IATA: CE | | ICAO1 |
| 6305 | NTWD | NATIONWIDE TRANSPORTATION INC | | | SCAC3 |
| 6306 | NTWG | NATIONWIDE TOWING INC | | | SCAC3 |
| 6307 | NTWG | NINE ZERO FIVE SEVEN-TWO EIGHT EIGH | | | SCAC4 |
| 6308 | NTWH | NATIONWIDE TRANSPORT INC | | | SCAC4 |
| 6309 | NTWI | NATIONWIDE TRANSPORT & WAREHOUSE IN | | | SCAC3 |
| 6310 | NTWM | NETWORK MESSENGER SERVICE INC | | | SCAC3 |
| 6311 | NTWM | NETWORK MESSENGER SERVICE INC | | | SCAC4 |
| 6312 | NTWN | NORTHWESTERN TRANSPORT | | | SCAC4 |
| 6313 | NTWO | NETWORK COURIER SERVICE | | | SCAC3 |
| 6314 | NTWO | NETWORK GLOBAL LOGISTICS LLC | | | SCAC4 |
| 6315 | NTWQ | NEW TERMINAL WAREHOUSE CORPORATION | | | SCAC3 |
| 6316 | NTWQ | NINE ZERO THREE TWO-TWO SEVEN SIX N | | | SCAC4 |
| 6317 | NTWR | NETWORK ENTERPRISE CORPORATION | | | SCAC3 |
| 6318 | NTWR | Network Rail | | GB | TRAFFIC |
| 6319 | NTWS | NATIONAL WRECKER INC | | | SCAC3 |
| 6320 | NTWS | NINE ONE TWO TWO- SEVEN ONE SIX FIV | | | SCAC4 |
| 6321 | NTWT | NORTHWAY TRUCKING | | | SCAC3 |
| 6322 | NTWV | NORMAN TRUCKING COMPANY | | | SCAC3 |
| 6323 | NTWW | NORTHWOODS HEATING AND SUPPLY | | | SCAC4 |
| 6324 | NTWY | NORTHWAY TRANSFER INC | | | SCAC3 |
| 6325 | NTX | Northern Air Service, Inc. | Callsign: Nortax, Name changed to Northern Jet Management, Inc. | USA | AVCODES |
| 6326 | NTX | Northern Jet Management, Inc. | Callsign: Nortax, Name changed from Northern Air Service, Inc. | USA | AVCODES |
| 6327 | NTX | AK-Air Georgia, LLC | Callsign: Tiflis, | GE | AVCODES |
| 6328 | NTX | Northern Jet Management | | | ICAO1 |
| 6329 | NTX | National Tube Co. | 8/1920-4/1938 | | NAKINA |
| 6330 | NTX | National Tube Co. | Apr-38 | | NRHS |
| 6331 | NTX | NATIONAL TUBE CO. | | | PWRC |
| 6332 | NTXA | NORTH TEXAS CARRIER CORP | | | SCAC4 |
| 6333 | NTXG | NATOS TRANSPORT | | | SCAC4 |
| 6334 | NTXI | NEWBERRY TAXI CO | | | SCAC3 |
| 6335 | NTXI | NETWORK XPRESS INC | | | SCAC4 |
| 6336 | NTXL | NORTH TEXAS LINES INC | | | SCAC3 |
| 6337 | NTXL | NP TRANSPORT LLC | | | SCAC4 |
| 6338 | NTXM | NELLIE TRANSPORT | | | SCAC4 |
| 6339 | NTXO | NEES TRANSPORT LLC | | | SCAC4 |
| 6340 | NTXP | NORTHERN TEX-PACK EXPRESS INC | | | SCAC3 |
| 6341 | NTXP | NAVIGATOR TRUCKING EXPRESS CORP | | | SCAC4 |
| 6342 | NTXR | NEBRASKA-TEXAS TRANSPORTATION INC | | | SCAC4 |
| 6343 | NTXY | NEUMAN TRANSPORT INC | | | SCAC4 |
| 6344 | NTYH | NICHOLSON, TERRY HAULAGE INC | | | SCAC4 |
| 6345 | NTYU | New Transit Yurikamome | City: Tokyo, formerly Tokyo Waterfront New Transit Waterfront Line | J | TRAFFIC |
| 6346 | NTZ | NATIONAL TACONITE | | | PWRC |
| 6347 | NTZC | NINE TWO ZERO ONE-FOUR FOUR SIX THR | | | SCAC4 |
| 6348 | NTZE | NINE TWO ZERO NINE-FOUR FIVE ONE FI | | | SCAC4 |
| 6349 | NTZN | NINE TWO ZERO SIX-TWO THREE NINE SE | | | SCAC4 |
| 6350 | NTZO | NINE TWO ZERO NINE-FOUR FIVE ONE FI | | | SCAC4 |
| 6351 | NTZP | NITZ, PETER | | | SCAC4 |
| 6352 | NTZR | Natchez Railway | | | RSRV |
| 6353 | NTZR | NATCHEZ RAILWAY LLC | | | SCAC4 |
| 6354 | NTZS | NINE ONE FIVE FIVE-THREE ZERO SEVEN | | | SCAC4 |
| 6355 | NTZT | NINE THREE ZERO THREE ONE THREE (93 | | | SCAC4 |
| 6356 | NU | Japan Transocean Air Co. Ltd. | ICAO: JTA, Callsign: Jai Ocean, IATA Prefix: 353, | J | AVCODES |
| 6357 | NU | Aero Contractors Company of Nigeria Ltd. | ICAO: NIG, Callsign: Aeroline, IATA Designator changed to AJ | WAN | AVCODES |
| 6358 | NU | Southwest Airlines | ICAO: SWL, Callsign: Nansei, | USA | AVCODES |
| 6359 | NU | Southwest Air Lines Ltd. | ICAO: SWL, Callsign: Nansei, | USA | AVCODES |
| 6360 | NUA | Private Airline Services Ltd. | Callsign: United Nigeria, | WAN | AVCODES |
| 6361 | NUA | United Nigeria Airlines Company Limited | IATA: U5, Callsign: United Nigeria, | WAN | AVCODES |
| 6362 | NUAG | NATURAL AG | | | SCAC3 |
| 6363 | NUB | Nomad Aviation (Europe) Ltd. | Callsign: Valletta, | M | AVCODES |
| 6364 | NUBC | NUNNER BUS CO INC | | | SCAC3 |
| 6365 | NUBE | NEUBER ENVIROMENTAL SERVICES INC | | | SCAC4 |
| 6366 | NUBN | NUTRA BLEND CORPORATION | | | SCAC4 |
| 6367 | NUBO | NUNES BROS TRUCKING CO | | | SCAC3 |
| 6368 | NUBO | NUMBER ONE MACHINING LTD | | | SCAC4 |
| 6369 | NUBT | NUCKOLS BROS TRUCKING INC | | | SCAC3 |
| 6370 | NUCA | NU-CAR CARRIERS, INC | | | SCAC3 |
| 6371 | NUCD | NU-CAR DRIVEAWAY INC | | | SCAC3 |
| 6372 | NUCD | NOUVELLE SHIPMANAGEMENT CO | | | SCAC4 |
| 6373 | NUCH | NUCHERENO, GARY | | | SCAC4 |
| 6374 | NUCO | NUCO TRUCK LINES INC | | | SCAC3 |
| 6375 | NUCX | Nucor Steel Crawfordsville—Division of Nucor Corp. | added 4/1997; eliminated 7/1997; 7/2000-7/2005 (not listed) | | NAKINA |
| 6376 | NUCX | Nucor Steel Crawfordsville--Division of Nucor Corp. | added 4/97; eliminated 7/97; 7/2000 | | NRHS |
| 6377 | NUCX | NUCOR STEEL CRAWFORDSVILLE, DIV. NUCOR CORP. | | | PWRC |
| 6378 | NUCX | NUCOR STEEL CRAWFORDSVILLE - DIVISION OF NUCOR CORP | | | PWRC |
| 6379 | NUCX | Nucor Steel Crawfordsville | | | RSRV |
| 6380 | NUDU | SCM Inc. | | | RSRV |
| 6381 | NUDY | NU DAY TRANSPORT SERVICE INC | | | SCAC4 |
| 6382 | NUEA | NU-ERA LOGISTICS INC | | | SCAC4 |
| 6383 | NUEQ | NUELSEN, GEORGE A TEAMING COMPANY | | | SCAC3 |
| 6384 | NUEX | Nucor Steel Arkansas | added 7/2003; eliminated 4/2004; 7/2005 (not listed) | | NAKINA |
| 6385 | NUEX | NUCOR STEEL ARKANSAS, DIV. NUCOR CORP. | | | PWRC |
| 6386 | NUEX | NUCOR STEEL ARKANSAS | | | SCAC4 |
| 6387 | NUGE | NUGGET EXPRESS INC | | | SCAC3 |
| 6388 | NUGL | NUGGETT LEASING INC | | | SCAC3 |
| 6389 | NUHN | NUHN INDUSTRIES LTD | | | SCAC4 |
| 6390 | NUIU | Triton Container International | | | RSRV |
| 6391 | NUIU | TRITON CONTAINER INTERNATIONAL CORP | | | SCAC4 |
| 6392 | NUK | Strait Air (2000) Ltd | Callsign: Nanuck, | CDN | AVCODES |
| 6393 | NUKA | NUKALA FREIGHT LINES INC | | | SCAC3 |
| 6394 | NUKL | NOURI TRUCKING LLC | | | SCAC4 |
| 6395 | NUL | Aeroservicios de Nuevo Leon, S.A. de C.V. | Callsign: Servicios Nuevoleon, | MEX | AVCODES |
| 6396 | NUL | Aeroservicios De Nuevo Leon | | | ICAO1 |
| 6397 | NULG | NAVIERAS ULTRAGAS LTDA | | | SCAC4 |
| 6398 | NULI | NUCO LOGISTICS INC | | | SCAC4 |
| 6399 | NULO | NU LINE TRANSPORTATION INC | | | SCAC4 |
| 6400 | NULS | NUTMEG LIVERY SERVICE | | | SCAC3 |
