| 4301 | PIMN | PREMIER INTERNATIONAL MOVERS | | | SCAC4 |
| 4302 | PIMO | PIONEER MOVING & STORAGE | | | SCAC3 |
| 4303 | PIMS | PIONEER MOTOR SERVICE, INC | | | SCAC3 |
| 4304 | PIMT | PIEDMONT TRANSPORTATION CO INC | | | SCAC3 |
| 4305 | PIMT | POTSDAM IMPORTERS INC | | | SCAC4 |
| 4306 | PIMU | PIMK LTD | | BG | BIC |
| 4307 | PIN | Pacific International Airlines, Inc. | Callsign: Road runners, | USA | AVCODES |
| 4308 | PIN | Pacific International Airlines | | | ICAO1 |
| 4309 | PINA | PITTSBURGH NORTH AIRE-RIDE | | | SCAC4 |
| 4310 | PINB | PORTER INCORPORATED | | | SCAC4 |
| 4311 | PINC | PINNACLE FREIGHT LINES INC | | | SCAC4 |
| 4312 | PIND | PINDERS TRANSFER INC | | | SCAC3 |
| 4313 | PINE | PINEY BRANCH MOTORS, INCORPORATED | | | SCAC3 |
| 4314 | PING | PLASTICOM INC | | | SCAC4 |
| 4315 | PINH | PINCHAM, H H MOVING CO | | | SCAC3 |
| 4316 | PINI | PINCIN TRUCKING INC | | | SCAC3 |
| 4317 | PINI | PRESCOTT INTERIORS INC | | | SCAC4 |
| 4318 | PINJ | PA INC | | | SCAC4 |
| 4319 | PINL | PINAL WAREHOUSE CO INC | | | SCAC3 |
| 4320 | PINL | PACIFIC INLAND XPRESS LTD | | | SCAC4 |
| 4321 | PINM | PREFERRED TRANSPORTATION INC | | | SCAC3 |
| 4322 | PINM | PREFERRED TRANSPORTATION INC | | | SCAC4 |
| 4323 | PINN | PINNERS TRANSPORTATION | | | SCAC3 |
| 4324 | PINO | PINOY | | | SCAC4 |
| 4325 | PINP | PINPOINT INFORMATION SYSTEMS | | | SCAC4 |
| 4326 | PINQ | PENMANS | | | SCAC4 |
| 4327 | PINT | PINTO, A T INC | | | SCAC3 |
| 4328 | PINT | PINTO, A T INC | | | SCAC4 |
| 4329 | PINW | PEOPLES INTERNATIONAL | | | SCAC3 |
| 4330 | PINX | Pinnacle Polymers | added 4/2007 | | NAKINA |
| 4331 | PINX | PINNACLE POLYMERS | | | PWRC |
| 4332 | PINX | PINNACLE POLYMERS | | | SCAC4 |
| 4333 | PINY | PINER OIL CO INC | | | SCAC4 |
| 4334 | PINZ | PETERSON INDUSTRIES | | | PWRC |
| 4335 | PINZ | Pinzgauer | | A | TRAFFIC |
| 4336 | PIO | Pioneer Airlines, Inc. | Callsign: Pioneer, | USA | AVCODES |
| 4337 | PIO | Pioneer Airlines | | | ICAO1 |
| 4338 | PIOA | PRIORITY AIR FREIGHT SERVICE INC | | | SCAC3 |
| 4339 | PIOA | PIONEER INDUSTRIES INC | | | SCAC4 |
| 4340 | PIOB | PIONEER BULK CARRIERS | | | SCAC3 |
| 4341 | PIOC | PITTMAN OIL INC | | | SCAC4 |
| 4342 | PIOE | PIONEER EXPRESS COMPANY | | | SCAC3 |
| 4343 | PIOF | PIONEER FREIGHT SYSTEMS INC | | | SCAC3 |
| 4344 | PIOH | PIONEER (A DIV OF AMERICAN TRANSPOR | | | SCAC3 |
| 4345 | PIOI | PIONEER STORAGE SERVICE INC | | | SCAC3 |
| 4346 | PIOI | PIONEER TRANSPORT INC | | | SCAC4 |
| 4347 | PIOK | PITTSBURGH-OAKLAND ENTERPRISES INC | | | SCAC3 |
| 4348 | PIOL | PIONEER LINES | | | SCAC3 |
| 4349 | PIOL | PIONEER LOG FURNITURE | | | SCAC4 |
| 4350 | PIOM | Piombino Steel Works | | I | TRAFFIC |
| 4351 | PION | PIONEER TRAILS | | | SCAC3 |
| 4352 | PIONEER | Pioneer | | US-NY | TRAFFIC |
| 4353 | PIOO | PIONEER FLOUR MILLS | | | SCAC4 |
| 4354 | PIOP | PIONEER PIPE LINE COMPANY | | | SCAC3 |
| 4355 | PIOS | PIONEER SMELTING CO | | | SCAC3 |
| 4356 | PIOT | PIONEER TRANSPORTATION SYSTEMS INC | | | SCAC3 |
| 4357 | PIOU | PIONEER SHIPPING LTD | | | SCAC3 |
| 4358 | PIOU | PIONEER SHIPPING LTD | | | SCAC4 |
| 4359 | PIOV | PIONEER VAN LINES INC | | | SCAC3 |
| 4360 | PIOW | PIONEER WAREHOUSE CARRIERS INC | | | SCAC3 |
| 4361 | PIOX | Pioneer Iron & Metal Co. | added 4/1971; 1/1975; eliminated 7/1979 | | NAKINA |
| 4362 | PIOX | Pioneer Iron & Metal Co. | added 4/71; 1/75; eliminated 7/79 | | NRHS |
| 4363 | PIOX | PIONEER AMERICAS, INC. [PIONEER IRON & METAL CO.] | | | PWRC |
| 4364 | PIOY | PRIORITY TRUCKING INC | | | SCAC3 |
| 4365 | PIP | Aerokoncept Ltd. | Callsign: Aerokoncept, | RUS | AVCODES |
| 4366 | PIP | Platinum Airways Co. Ltd. | Callsign: Thai Platinum, | T | AVCODES |
| 4367 | PIP | Pilot Flyskole Flygerforening (PIFF) | Callsign: Pilot, | N | AVCODES |
| 4368 | PIPC | PIPECO INC | | | SCAC3 |
| 4369 | PIPD | PROLINE TRANSPORT INC | | | SCAC3 |
| 4370 | PIPD | PIPE CREEK TRADING COMPANY | | | SCAC4 |
| 4371 | PIPE | PIPELINE SERVICES INC | | | SCAC3 |
| 4372 | PIPER | Piper Aircraft Inc. | | US-FL | TRAFFIC |
| 4373 | PIPF | PIPEFUSION SERVICES INC | | | SCAC4 |
| 4374 | PIPH | PIPER, E H TRUCKING | | | SCAC3 |
| 4375 | PIPL | PIPELINE INDUSTRIES INC | | | SCAC3 |
| 4376 | PIPM | PIPHO MILK TRANSPORT INC | | | SCAC3 |
| 4377 | PIPN | PINEY POINT INDUSTRIES | | | SCAC3 |
| 4378 | PIPO | PIONEER TRANSPORT, INC | | | SCAC3 |
| 4379 | PIPO | PIONEER TRANSPORT INC | | | SCAC4 |
| 4380 | PIPP | PIPPIN, EARL TRANSPORTER | | | SCAC3 |
| 4381 | PIPQ | PITTSBURGH PHILADELPHIA TRANSPORTAT | | | SCAC3 |
| 4382 | PIPQ | PIPEX INC | | | SCAC4 |
| 4383 | PIPR | PIPCO TRANSPORTATION INC | | | SCAC3 |
| 4384 | PIPR | PIPCO TRANSPORTATION INC | | | SCAC4 |
| 4385 | PIPT | PIPELINE TRANSPORTATION | | | SCAC4 |
| 4386 | PIPY | PISONY INTERNATIONAL PIPELINE EQUIP | | | SCAC4 |
| 4387 | PIPZ | PINEY POINT PHOSPHATES, INC. | | | PWRC |
| 4388 | PIQA | PIQUA TRANSFER & STORAGE COMPANY | | | SCAC3 |
| 4389 | PIQO | PIONEER OIL | | | SCAC4 |
| 4390 | PIR | Pamir Air | IATA: NR, Callsign: Pamir, Designator NR* reinstated by IATA | AFG | AVCODES |
| 4391 | PIR | Pamir Airways | IATA: PM, Callsign: Pamir, Ceased operations in 2011. | AFG | AVCODES |
| 4392 | PIR | Pamir Airways | IATA: NR | | ICAO1 |
| 4393 | PIR | Pittsburgh Industrial R.R., Inc. (to POHC) | added 4/1997; 7/2000; eliminated 4/2001; 7/2005 | | NAKINA |
| 4394 | PIR | Pittsburgh Industrial R.R., Inc. (to POHC) | added 4/97; 7/2000; eliminated 4/2001 | | NRHS |
| 4395 | PIR | PITTSBURGH INDUSTRIAL RAILROAD INC. | | | PWRC |
| 4396 | PIR | Pittsburgh Industrial Railroad | | | RSRV |
| 4397 | PIRA | POOLE FARM INC | | | SCAC4 |
| 4398 | PIRAN | | City: Piran | SLO | TRAFFIC |
| 4399 | PIRB | PITRIA RAINBOW AND OWNERS | | | SCAC3 |
| 4400 | PIRE | PANIRENE MARITIME INC | | | SCAC3 |
