| 1 | PIO | Pioneer Airlines, Inc. | Callsign: Pioneer, | USA | AVCODES |
| 2 | PIO | Pioneer Airlines | | | ICAO1 |
| 3 | PIOA | PRIORITY AIR FREIGHT SERVICE INC | | | SCAC3 |
| 4 | PIOA | PIONEER INDUSTRIES INC | | | SCAC4 |
| 5 | PIOB | PIONEER BULK CARRIERS | | | SCAC3 |
| 6 | PIOC | PITTMAN OIL INC | | | SCAC4 |
| 7 | PIOE | PIONEER EXPRESS COMPANY | | | SCAC3 |
| 8 | PIOF | PIONEER FREIGHT SYSTEMS INC | | | SCAC3 |
| 9 | PIOH | PIONEER (A DIV OF AMERICAN TRANSPOR | | | SCAC3 |
| 10 | PIOI | PIONEER STORAGE SERVICE INC | | | SCAC3 |
| 11 | PIOI | PIONEER TRANSPORT INC | | | SCAC4 |
| 12 | PIOK | PITTSBURGH-OAKLAND ENTERPRISES INC | | | SCAC3 |
| 13 | PIOL | PIONEER LINES | | | SCAC3 |
| 14 | PIOL | PIONEER LOG FURNITURE | | | SCAC4 |
| 15 | PIOM | Piombino Steel Works | | I | TRAFFIC |
| 16 | PION | PIONEER TRAILS | | | SCAC3 |
| 17 | PIONEER | Pioneer | | US-NY | TRAFFIC |
| 18 | PIOO | PIONEER FLOUR MILLS | | | SCAC4 |
| 19 | PIOP | PIONEER PIPE LINE COMPANY | | | SCAC3 |
| 20 | PIOS | PIONEER SMELTING CO | | | SCAC3 |
| 21 | PIOT | PIONEER TRANSPORTATION SYSTEMS INC | | | SCAC3 |
| 22 | PIOU | PIONEER SHIPPING LTD | | | SCAC3 |
| 23 | PIOU | PIONEER SHIPPING LTD | | | SCAC4 |
| 24 | PIOV | PIONEER VAN LINES INC | | | SCAC3 |
| 25 | PIOW | PIONEER WAREHOUSE CARRIERS INC | | | SCAC3 |
| 26 | PIOX | Pioneer Iron & Metal Co. | added 4/1971; 1/1975; eliminated 7/1979 | | NAKINA |
| 27 | PIOX | Pioneer Iron & Metal Co. | added 4/71; 1/75; eliminated 7/79 | | NRHS |
| 28 | PIOX | PIONEER AMERICAS, INC. [PIONEER IRON & METAL CO.] | | | PWRC |
| 29 | PIOY | PRIORITY TRUCKING INC | | | SCAC3 |
