| 1 | PIR | Pamir Air | IATA: NR, Callsign: Pamir, Designator NR* reinstated by IATA | AFG | AVCODES |
| 2 | PIR | Pamir Airways | IATA: PM, Callsign: Pamir, Ceased operations in 2011. | AFG | AVCODES |
| 3 | PIR | Pamir Airways | IATA: NR | | ICAO1 |
| 4 | PIR | Pittsburgh Industrial R.R., Inc. (to POHC) | added 4/1997; 7/2000; eliminated 4/2001; 7/2005 | | NAKINA |
| 5 | PIR | Pittsburgh Industrial R.R., Inc. (to POHC) | added 4/97; 7/2000; eliminated 4/2001 | | NRHS |
| 6 | PIR | PITTSBURGH INDUSTRIAL RAILROAD INC. | | | PWRC |
| 7 | PIR | Pittsburgh Industrial Railroad | | | RSRV |
| 8 | PIRA | POOLE FARM INC | | | SCAC4 |
| 9 | PIRAN | | City: Piran | SLO | TRAFFIC |
| 10 | PIRB | PITRIA RAINBOW AND OWNERS | | | SCAC3 |
| 11 | PIRE | PANIRENE MARITIME INC | | | SCAC3 |
| 12 | PIRI | PIRIE MOTOR FREIGHT INC | | | SCAC3 |
| 13 | PIRM | PLYMOUTH IRON & METAL INC | | | SCAC3 |
| 14 | PIRO | PIROSMANI SHIPPING CO LTD | | | SCAC3 |
| 15 | PIRP | PIONEER PLASTICS | | | SCAC3 |
| 16 | PIRP | PIONEER PACKAGING | | | SCAC4 |
| 17 | PIRQ | PEEL, IRENE | | | SCAC4 |
| 18 | PIRR | PIONEER TOURS INC | | | SCAC3 |
| 19 | PIRS | PRECISION TRANSPORT INC | | | SCAC4 |
| 20 | PIRT | PIROLLO TRANSPORT CO INC | | | SCAC3 |
| 21 | PIRU | PROVINI OF IRAN, S.A. | | | SCAC3 |
