| 1301 | IHOU | INTERMODAL TANK TRANSPORT INC. | | USA | BIC |
| 1302 | IHOU | Intermodal Tank Transport | | | RSRV |
| 1303 | IHOU | INTERMODAL TANK TRANSPORT INC | | | SCAC4 |
| 1304 | IHP | INAER Helicopter Portugal Lda | Name changed to Babcock Mission Critical Services Portugal Lda. | P | AVCODES |
| 1305 | IHP | Babcock Mission Critical Services Portugal Lda. | Name changed from INAER Helicopter Portugal Lda. | P | AVCODES |
| 1306 | IHPP | INTERNATIONAL SHIPPING AGENCY INC. | | | SCAC4 |
| 1307 | IHRC | Wabash & Erie R.R. | added 1/1995 | | NAKINA |
| 1308 | IHRC | Indiana Hi-Rail Corp. | added 4/1995; eliminated 7/1998; 7/2000-7/2005 | | NAKINA |
| 1309 | IHRC | Indiana Hi-Rail Corp. | added 4/1982; 1/1994; eliminated 1/1995 | | NAKINA |
| 1310 | IHRC | Indiana Hi-Rail Corp. | added 4/82; 1/94; eliminated 1/95 | | NRHS |
| 1311 | IHRC | Wabash & Erie R.R. | added 1/95 | | NRHS |
| 1312 | IHRC | Indiana Hi-Rail Corp. | added 4/95; eliminated 7/98; 7/2000 | | NRHS |
| 1313 | IHRC | INDIANA HI-RAIL CORP. [(WAER) WABASH & ERIE RAILROAD] | | | PWRC |
| 1314 | IHRC | Indiana Hi-Rail Corporation | | | RSRV |
| 1315 | IHRC | Indiana Hi-Rail Corp. | | USA | TRAFFIC |
| 1316 | IHS | Thyrluthjonustan | | IS | AVCODES |
| 1317 | IHS | Thryluthjonustan | | | ICAO1 |
| 1318 | IHS | IG Historischer Schienenverkehr e.V. | Schierwaldenrath | D | privat-bahn.de |
| 1319 | IHSE | I H S ENTERPRISES INC | | | SCAC4 |
| 1320 | IHSX | Western Vancouver Island Heritage Society (Alberni Pacific Ry.) | 7/2000-7/2005 (not listed) | | NAKINA |
| 1321 | IHSX | Western Vancouver Island Heritage Society (Alberni Pacific Ry.) | Jul-00 | | NRHS |
| 1322 | IHSX | WESTERN VANCOUVER ISLAND HERITAGE SOCIETY (ALBERNI PACIFIC RAILWAY) | | | PWRC |
| 1323 | IHSX | Alberni Pacific Railway (Western Vancouver Island Heritage Society) | | | RSRV |
| 1324 | IHSX | WESTERN VANCOUVER ISLAND INDUSTRIAL | | | SCAC4 |
| 1325 | IHTA | IRON HORSE TRANSPORTATION | | | SCAC4 |
| 1326 | IHTD | IRON HORSE TRUCKING INC | | | SCAC4 |
| 1327 | IHTM | IRON HAWK TRUCKING INC | | | SCAC4 |
| 1328 | IHTO | INTERSTATE HAZMAT TRANSPORT INC | | | SCAC4 |
| 1329 | IHTR | IRON HORSE TRUCKING LLC | | | SCAC4 |
| 1330 | IHTS | IRON HORSE TRUCK SHUTTLE LTD | | | SCAC4 |
| 1331 | IHTU | ITC HOLLAND TRANSPORT B.V | | NL | BIC |
| 1332 | IHTU | ITC HOLLAND TRANSPORT BV | | | SCAC4 |
| 1333 | IHXP | IRON HORSE EXPRESS INC | | | SCAC4 |
| 1334 | IHXX | IRON HIGHWAY, INC. | | | PWRC |
| 1335 | II | IBC Airways, Inc. | ICAO: CSQ, Callsign: Chasqui, IATA Prefix: 175, formerly IBC Aviation Services Inc., d/b/a Western Air Freight | USA | AVCODES |
| 1336 | II | Business Air Ltd. | ICAO: GNT, Callsign: Granite, Merged with British Midland Regional Limited on 05 February 2001. Established in 1987. Commenced operations in August 1987. | GB | AVCODES |
| 1337 | II | Eurocity Express Ltd. | ICAO: LCY, Callsign: Stol, Renamed London city Airways Ltd. | GB | AVCODES |
| 1338 | II | London City Airways Ltd. | ICAO: LCY, Callsign: Stol, Merged into British Midland. Formerly Eurocity Express Ltd. | GB | AVCODES |
| 1339 | II | Airways (India) Ltd. | Callsign: Airways, Designator II recalled by IATA | IND | AVCODES |
| 1340 | II | Evex Fluggsellschaft mbh & Co KG | Callsign: Sunbeam, | D | AVCODES |
| 1341 | IIA | Interamericana de Aviacon Ltda. | Callsign: Interamericana, | CO | AVCODES |
| 1342 | IIA | Inter Iles Air | IATA: I7, Callsign: Inter Iles, | COM | AVCODES |
| 1343 | IIAF | Imperial Iranian Air Force | | IR | TRAFFIC |
| 1344 | IIC | Inter Island Air Charter | Callsign: Inter Air, | BS | AVCODES |
| 1345 | IICL | ITS INTERNATIONAL CONTAINER LINES I | | | SCAC4 |
| 1346 | IICU | IWATANI CORPORATION | | J | BIC |
| 1347 | IICU | IWATANI INTERNATIONAL CORPORATION | | | SCAC4 |
| 1348 | IICX | Interlake Iron Corp. | 4/1938-4/1961; eliminated 7/1965 (reporting marks changed to ISCX) | | NAKINA |
| 1349 | IICX | Interlake Iron Corp. (Toledo Furnace Plant) | 7/1932-7/1937 | | NAKINA |
| 1350 | IICX | Interlake Iron Corp. (Toledo Furnace Plant) | Apr-38 | | NRHS |
| 1351 | IICX | Interlake Iron Corp. | 1/52-4/61; eliminated 7/65 (reporting marks changed to ISCX) | | NRHS |
| 1352 | IICX | INTERLAKE IRON CORP. (MERK CHANGED TO ISCX 7-95) | | | PWRC |
| 1353 | IICZ | CANADIAN NATIONAL RWY [ILLINOIS CENTRAL GULF RAILROAD; ILLINOIS CENTRAL RR] | | | PWRC |
| 1354 | IICZ | Illinois Central Railroad (Canadian National Railway) | | | RSRV |
| 1355 | IIDP | INSTRUMENTOS INDUSTRIALES DEL PACIF | | | SCAC4 |
| 1356 | IIDU | INTERMODAL INNOVATION LLP | | | SCAC4 |
| 1357 | IIET | IET INTERNATIONAL ENERGY TECHNOLOGI | | | SCAC4 |
| 1358 | IIG | International Company for Transport, Trade and Public Works | Callsign: Aldawlyh Air, | LAR | AVCODES |
| 1359 | IIG | International Company for Transport, Trade and Pub | | | ICAO1 |
| 1360 | IIIC | INNOVATIVE INTERMODAL INC | | | SCAC4 |
| 1361 | IIID | INTRADE INDUSTRIES INC | | | SCAC4 |
| 1362 | IIII | IRONWORKS INDUSTRIES INCORPORATED | | | SCAC4 |
| 1363 | IIIN | IFYCO INVESTMENT INC | | | SCAC4 |
| 1364 | IIIU | III TRANSPORTATION | | | PWRC |
| 1365 | IIIU | III Transportation | | | RSRV |
| 1366 | IIIZ | III TRANSPORTATION | | | PWRC |
| 1367 | IIIZ | III Transportation | | | RSRV |
| 1368 | IIIZ | IOWA INTERSTATE INTERMODAL | | | SCAC4 |
| 1369 | IIL | India International Airways (P) Ltd. | Callsign: India Inter, | IND | AVCODES |
| 1370 | IIL | India International Airways | | | ICAO1 |
| 1371 | IILA | INTERTRANSPORT INTERNATIONAL | | | SCAC4 |
| 1372 | IILL | IDEAL INSTALLATION LLC | | | SCAC4 |
| 1373 | IILU | (IPCU) INDEPENDENT CONTAINER LINE | | | PWRC |
| 1374 | IILU | Independent Container Line | | | RSRV |
| 1375 | IILU | INDEPENDENT CONTAINER LINE LTD | | | SCAC1 |
| 1376 | IILU | INDEPENDENT CONTAINER LINE | | | SCAC4 |
| 1377 | IILZ | (IPCU) INDEPENDENT CONTAINER LINE | | | PWRC |
| 1378 | IILZ | Independent Container Line | | | RSRV |
| 1379 | IILZ | INDEPENDENT CONTAINER LINE | | | SCAC4 |
| 1380 | IIMI | INTEGRITY IN MOTION INC | | | SCAC4 |
| 1381 | IIMS | INDEPENDENCE INTERNATIONAL MOVING A | | | SCAC4 |
| 1382 | IIN | Inter Island Airlines Lda | | CV | AVCODES |
| 1383 | IIN | Inter Islands Airlines | IATA: H4, Designator H4 reinstated by IATA | CV | AVCODES |
| 1384 | IIN | Inter Islands Airlines | IATA: H4 | | ICAO1 |
| 1385 | IINA | ILLIANA TRANSPORTATION, INC | | | SCAC1 |
| 1386 | IINA | ILLIANA TRANSPORTATION INC | | | SCAC4 |
| 1387 | IIND | INTERSPED INC | | | SCAC4 |
| 1388 | IINO | IINO LINES | | | SCAC4 |
| 1389 | IINQ | INTER INC | | | SCAC4 |
| 1390 | IIPI | INTER ISLAND PETROLEUM INC | | | SCAC4 |
| 1391 | IIRC | Indiana Interstate Ry. Co., Inc. | added 4/1978; 1/1980; added 7/1980; eliminated 1/1983 | | NAKINA |
| 1392 | IIRC | Indiana Interstate Ry. Co., Inc. | added 4/78; 1/80; added 7/80; eliminated 1/83 | | NRHS |
| 1393 | IIRC | INDIANA INTERSTATE RAILWAY CO. | | | PWRC |
| 1394 | IIRC | Indiana Interstate Railway | | | RSRV |
| 1395 | IIRX | Independence Iowa Refrigerator Line | 7/1930-7/1935 | | NAKINA |
| 1396 | IIRX | INDEPENDENCE IOWA REFRIGERATOR LINE | | | PWRC |
| 1397 | IIRZ | III TRANSPORTATION | | | PWRC |
| 1398 | IIRZ | III Transportation | | | RSRV |
| 1399 | IIRZ | III TRANSPORTATION | | | SCAC4 |
| 1400 | IISC | INTERNATIONAL INDUSTRIAL SUPPLIES | | | SCAC4 |
