| 1 | NAU | Antanik-Air | Callsign: Antanik, | UA | AVCODES |
| 2 | NAU | Danaus Lineas Aereas, S.A. de C.V. | Callsign: Danaus, Ceased operations. | MEX | AVCODES |
| 3 | NAU | Antanik-Air | | | ICAO1 |
| 4 | NAUG | Naugatuck R.R. Co., Inc. | 7/2000-7/2005 | | NAKINA |
| 5 | NAUG | Naugatuck R.R. Co., Inc. | Jul-00 | | NRHS |
| 6 | NAUG | NAUGATUCK RAILROAD CO. | | | PWRC |
| 7 | NAUG | Naugatuck Railroad | | | RSRV |
| 8 | NAUG | NAUGATUCK RAILROAD COMPANY INC | | | SCAC4 |
| 9 | NAUK | NORTH ATLANTIC UNITED KINGDOM FREIG | | | SCAC3 |
| 10 | NAUL | NATURAL TRUCK LEASING INC | | | SCAC3 |
| 11 | NAUM | NAUGHTON, MARY | | | SCAC4 |
| 12 | NAUM | | City: Naumburg | D | TRAFFIC |
| 13 | NAUO | NATIONWIDE AUTO TRANSPORT INC | | | SCAC3 |
| 14 | NAUO | NAO AUTO | | | SCAC4 |
| 15 | NAUQ | NATURAL TRANSPORT INC | | | SCAC4 |
| 16 | NAUR | NATURE CALVES LTD | | | SCAC4 |
| 17 | NAUS | NAUTILUIS LINES | | | SCAC3 |
| 18 | NAUT | NATIONAL AUTO TRANSPORT INC | | | SCAC3 |
