| 1 | NU | Japan Transocean Air Co. Ltd. | ICAO: JTA, Callsign: Jai Ocean, IATA Prefix: 353, | J | AVCODES |
| 2 | NU | Aero Contractors Company of Nigeria Ltd. | ICAO: NIG, Callsign: Aeroline, IATA Designator changed to AJ | WAN | AVCODES |
| 3 | NU | Southwest Airlines | ICAO: SWL, Callsign: Nansei, | USA | AVCODES |
| 4 | NU | Southwest Air Lines Ltd. | ICAO: SWL, Callsign: Nansei, | USA | AVCODES |
| 5 | NUA | Private Airline Services Ltd. | Callsign: United Nigeria, | WAN | AVCODES |
| 6 | NUA | United Nigeria Airlines Company Limited | IATA: U5, Callsign: United Nigeria, | WAN | AVCODES |
| 7 | NUAG | NATURAL AG | | | SCAC3 |
| 8 | NUB | Nomad Aviation (Europe) Ltd. | Callsign: Valletta, | M | AVCODES |
| 9 | NUBC | NUNNER BUS CO INC | | | SCAC3 |
| 10 | NUBE | NEUBER ENVIROMENTAL SERVICES INC | | | SCAC4 |
| 11 | NUBN | NUTRA BLEND CORPORATION | | | SCAC4 |
| 12 | NUBO | NUNES BROS TRUCKING CO | | | SCAC3 |
| 13 | NUBO | NUMBER ONE MACHINING LTD | | | SCAC4 |
| 14 | NUBT | NUCKOLS BROS TRUCKING INC | | | SCAC3 |
| 15 | NUCA | NU-CAR CARRIERS, INC | | | SCAC3 |
| 16 | NUCD | NU-CAR DRIVEAWAY INC | | | SCAC3 |
| 17 | NUCD | NOUVELLE SHIPMANAGEMENT CO | | | SCAC4 |
| 18 | NUCH | NUCHERENO, GARY | | | SCAC4 |
| 19 | NUCO | NUCO TRUCK LINES INC | | | SCAC3 |
| 20 | NUCX | Nucor Steel Crawfordsville—Division of Nucor Corp. | added 4/1997; eliminated 7/1997; 7/2000-7/2005 (not listed) | | NAKINA |
| 21 | NUCX | Nucor Steel Crawfordsville--Division of Nucor Corp. | added 4/97; eliminated 7/97; 7/2000 | | NRHS |
| 22 | NUCX | NUCOR STEEL CRAWFORDSVILLE, DIV. NUCOR CORP. | | | PWRC |
| 23 | NUCX | NUCOR STEEL CRAWFORDSVILLE - DIVISION OF NUCOR CORP | | | PWRC |
| 24 | NUCX | Nucor Steel Crawfordsville | | | RSRV |
| 25 | NUDU | SCM Inc. | | | RSRV |
| 26 | NUDY | NU DAY TRANSPORT SERVICE INC | | | SCAC4 |
| 27 | NUEA | NU-ERA LOGISTICS INC | | | SCAC4 |
| 28 | NUEQ | NUELSEN, GEORGE A TEAMING COMPANY | | | SCAC3 |
| 29 | NUEX | Nucor Steel Arkansas | added 7/2003; eliminated 4/2004; 7/2005 (not listed) | | NAKINA |
| 30 | NUEX | NUCOR STEEL ARKANSAS, DIV. NUCOR CORP. | | | PWRC |
| 31 | NUEX | NUCOR STEEL ARKANSAS | | | SCAC4 |
| 32 | NUGE | NUGGET EXPRESS INC | | | SCAC3 |
| 33 | NUGL | NUGGETT LEASING INC | | | SCAC3 |
| 34 | NUHN | NUHN INDUSTRIES LTD | | | SCAC4 |
| 35 | NUIU | Triton Container International | | | RSRV |
| 36 | NUIU | TRITON CONTAINER INTERNATIONAL CORP | | | SCAC4 |
| 37 | NUK | Strait Air (2000) Ltd | Callsign: Nanuck, | CDN | AVCODES |
| 38 | NUKA | NUKALA FREIGHT LINES INC | | | SCAC3 |
| 39 | NUKL | NOURI TRUCKING LLC | | | SCAC4 |
| 40 | NUL | Aeroservicios de Nuevo Leon, S.A. de C.V. | Callsign: Servicios Nuevoleon, | MEX | AVCODES |
| 41 | NUL | Aeroservicios De Nuevo Leon | | | ICAO1 |
| 42 | NULG | NAVIERAS ULTRAGAS LTDA | | | SCAC4 |
| 43 | NULI | NUCO LOGISTICS INC | | | SCAC4 |
| 44 | NULO | NU LINE TRANSPORTATION INC | | | SCAC4 |
| 45 | NULS | NUTMEG LIVERY SERVICE | | | SCAC3 |
| 46 | NUM | Nomad Aviation AG | Callsign: Bully, ICAO Callsign changed to Nomadjet. | CH | AVCODES |
| 47 | NUM | Nomad Aviation AG | Callsign: Nomadjet, ICAO Callsign changed from Bully. | CH | AVCODES |
| 48 | NUMA | Numajiri Railway | | J | TRAFFIC |
| 49 | NUMC | NAUPACTUS MARINE CO LTD CYPRUS | | | SCAC3 |
| 50 | NUMC | NAUPACTUS MARINE CO LTD | | | SCAC4 |
| 51 | NUMD | NUMED INC | | | SCAC4 |
| 52 | NUMI | NAUMANN TRANSFER MOVING & STORAGE C | | | SCAC3 |
| 53 | NUMK | NUMARK TRANSPORTATION | | | SCAC4 |
| 54 | NUMQ | NU-MINE COAL CO INC | | | SCAC3 |
| 55 | NUN | Nunasi-Central Airlines Ltd. | Callsign: Nunsai, | CDN | AVCODES |
| 56 | NUN | Nunasi-Central Airlines Ltd. | IATA: 6N, Callsign: Nunsai, Designator 6N recalled by IATA | CDN | AVCODES |
| 57 | NUN | Nunasi-Central Airlines | | | ICAO1 |
| 58 | NUNA | NUNEZ ALVAREZ, FRANCISCO | | | SCAC4 |
| 59 | NUNE | NUNN'S EXPRESS | | | SCAC4 |
| 60 | NUNH | NUNN, HOWARD INC | | | SCAC3 |
| 61 | NUNI | NUNES TRANSPORT INC | | | SCAC3 |
| 62 | NUNL | NUNLEY, H L TRUCKING CO | | | SCAC3 |
| 63 | NUNN | NUNN, CLAYTON | | | SCAC3 |
| 64 | NUNN | NUNEZ ANDRADE, RICARDO | | | SCAC4 |
| 65 | NUNV | NUNTIUS INVESTMENT CORP | | | SCAC4 |
| 66 | NUOC | NUMBER ONE CAB CO | | | SCAC3 |
| 67 | NUR | Avia-Nur | Callsign: Avia Nur, | KZ | AVCODES |
| 68 | NUR | Nawrs Air | | LAR | AVCODES |
| 69 | NUR | NATCHEZ, URANIA & RUSTON RAILWAY | | | PWRC |
| 70 | NURS | NURSERY TRANSPORTATION SERVICE INC | | | SCAC3 |
| 71 | NUS | Northern Illinois Flight Center, Inc | Callsign: Enjet, | USA | AVCODES |
| 72 | NUSA | NUGENT SAND COMPANY INC, THE | | | SCAC4 |
| 73 | NUSB | NUSSBERGER BROS TRUCKING CO | | | SCAC3 |
| 74 | NUSB | NUSSEY, CHAN TRUCKING | | | SCAC4 |
| 75 | NUSI | NATIONAL UNDERGROUND STORAGE INC | | | SCAC3 |
| 76 | NUSM | NUSSEY, MARVYN FARMS INC | | | SCAC4 |
| 77 | NUSN | NUSS INC | | | SCAC4 |
| 78 | NUSO | NUSSER OIL CO | | | SCAC4 |
| 79 | NUSP | NUSTAR TRANSPORT INC | | | SCAC4 |
| 80 | NUSS | NUSS TIMBER CO INC | | | SCAC3 |
| 81 | NUST | NUSSBAUM TRUCKING, INC | | | SCAC3 |
| 82 | NUST | NUSSBAUM TRUCKING INC | | | SCAC4 |
| 83 | NUSU | NEPTUNE ORIENT LINES, LTD. | | | PWRC |
| 84 | NUSU | Neptune Orient Lines | | | RSRV |
| 85 | NUSU | NEPTUNE ORIENT LINES, LTD. | | | SCAC3 |
| 86 | NUSU | APL CO PTE LTD-NOL GROUP | | | SCAC4 |
| 87 | NUSY | NUSSEY CARTAGE LIMITED | | | SCAC3 |
| 88 | NUSY | NUSSEY CARTAGE LIMITED | | | SCAC4 |
| 89 | NUSZ | NUCOR STEEL | | | PWRC |
| 90 | NUTA | NAUTAS SA DE C V MEXICO CITY MEX | | | SCAC3 |
| 91 | NUTB | NUTMEG BAKER SUPPLY CO, THE | | | SCAC3 |
| 92 | NUTC | NUNZIATO TRUCKING CO | | | SCAC3 |
| 93 | NUTF | NU-TRAFFIC INC | | | SCAC3 |
| 94 | NUTI | NU TREND TRANSPORTATION INC | | | SCAC3 |
| 95 | NUTI | NU TREND TRANSPORTATION INC | | | SCAC4 |
| 96 | NUTL | NU TREND LINES INC | | | SCAC3 |
| 97 | NUTR | NUTRI CAILLE LTEE | | | SCAC4 |
| 98 | NUTT | NUTT TRUCKING INC | | | SCAC3 |
| 99 | NUVC | NUVAC | | | SCAC4 |
| 100 | NUVE | NUEVA ESPERANZA CORPORLATION | | | SCAC3 |
