| 1 | NIS | Nicaraguenses de Aviacion S.A. (NICA) | IATA: 6Y, Callsign: Nica, Designator 6Y recalled by IATA | NIC | AVCODES |
| 2 | NIS | Nicaraguense De Aviacion | | | ICAO1 |
| 3 | NIS | Nishi-Nippon Railroad Co., Ltd (Nishitetsu) | | J | TRAFFIC |
| 4 | NISB | Nishitetsu Bus | | J | TRAFFIC |
| 5 | NISD | NISHIDA SHIPPING LTD. | | | SCAC3 |
| 6 | NISD | NISHAN TRANSPORT INC | | | SCAC4 |
| 7 | NISD | Nissan Diesel Motor Co. | | J | TRAFFIC |
| 8 | NISE | NIESE TRANSPORT INC | | | SCAC4 |
| 9 | NISEKO | Niseko Bus Co. | | J | TRAFFIC |
| 10 | NISH | NISHO SHIPPING CO LTD | | | SCAC3 |
| 11 | NISHIT | Nishi Tokyo Bus Co., Ltd. | | J | TRAFFIC |
| 12 | NISI | NISI SHIPPING COMPANY LIMITED | | | SCAC3 |
| 13 | NISN | NISSIN INTERNATIONAL TRANSPORT USA | | | SCAC3 |
| 14 | NISN | NISSIN INTERNATIONAL TRANSPORT USA | | | SCAC4 |
| 15 | NISP | NATIONAL SPINNING CO INC | | | SCAC3 |
| 16 | NISQ | NISTLER TRUCK | | | SCAC3 |
| 17 | NISR | Niigata Seaside Railway | Freight-only railway line, 1970 - 2002 | J | TRAFFIC |
| 18 | NISS | NISSUI SHIPPING CORPORATION, TOKYO | | | SCAC3 |
| 19 | NISS | NISSUI SHIPPING CORPORATION, TOKYO | | | SCAC4 |
| 20 | NISSAN | | | J | TRAFFIC |
| 21 | NISU | NORSUL INTERNACIONAL S A | | | SCAC3 |
| 22 | NISU | TECHNOPYR SA | | | SCAC4 |
| 23 | NISV | NATIONWIDE IMAGING SERVICES INC | | | SCAC4 |
| 24 | NISX | North American Car Corp. | added 4/1961; 4/1961-1/1975; eliminated 10/1979 | | NAKINA |
| 25 | NISX | North American Car Corp. | added 4/61; 4/61-1/75 | | NRHS |
| 26 | NISX | | | | TRAFFIC |
| 27 | NISZ | NATIONAL INDUSTRIAL SERVICES | | | PWRC |
