| 1 | PDT | Piedmont Airlines, Inc. d/b/a USAir Express | IATA: US, Callsign: Piedmont, IATA designator changed to PT | USA | AVCODES |
| 2 | PDT | Piedmont Airlines, Inc. | IATA: PT, Callsign: Piedmont, IATA designator changed from US* | USA | AVCODES |
| 3 | PDT | Piedmont Airlines (1948-1989) | IATA: PI | | ICAO1 |
| 4 | PDT | PARADISE TRAVEL INC | | | SCAC4 |
| 5 | PDTA | P & D TRANSPORTATION SERVICES | | | SCAC3 |
| 6 | PDTB | PREFERRED TRANSIT INC | | | SCAC4 |
| 7 | PDTC | PRODUCTIVE TRANSPORTATION CARRIER C | | | SCAC4 |
| 8 | PDTD | PENDEXTER, DAVID | | | SCAC4 |
| 9 | PDTG | PONDEROSA TRUCKING CO INC | | | SCAC3 |
| 10 | PDTH | PRAIRIELAND TRANSPORTATION INC | | | SCAC3 |
| 11 | PDTI | PRODUCE TRUCKING INC | | | SCAC3 |
| 12 | PDTJ | PRD TECHNOLOGIES INC | | | SCAC4 |
| 13 | PDTK | PADELFORD TRUCKING CORP | | | SCAC3 |
| 14 | PDTL | PRIDE TRUCK LINE LINC | | | SCAC3 |
| 15 | PDTM | P & D TRANSPORTATION SERVICES | | | SCAC3 |
| 16 | PDTO | P & D TRUCKING & LEASING CO | | | SCAC3 |
| 17 | PDTP | PIEDMONT TRANSPORTATION GROUP INC | | | SCAC4 |
| 18 | PDTQ | P & D TRUCKING | | | SCAC4 |
| 19 | PDTR | P & D TRUCKING INC | | | SCAC3 |
| 20 | PDTS | PERDUE TRANSPORTATION | | | SCAC3 |
| 21 | PDTS | PERDUE TRANSPORTATION INCORPORATED | | | SCAC4 |
| 22 | PDTT | PRODUCERS TRANSPORT, INC | | | SCAC3 |
| 23 | PDTT | POULIN, DANIEL TRANSPORT ENR | | | SCAC4 |
| 24 | PDTV | PAD TRAVEL | | | SCAC3 |
| 25 | PDTW | PRIFTI, DONALD TOWING | | | SCAC3 |
| 26 | PDTX | P.D. Transportation Co. | added 1/1974; 1/1975; eliminated 10/1978 | | NAKINA |
| 27 | PDTX | P.D. Transportation Co. | added 1/74; 1/75; eliminated 10/78 | | NRHS |
| 28 | PDTX | P. D. TRANSPORTATION CO. | | | PWRC |
