| 1 | PTO | North West Geomatics Ltd. | Callsign: Photo, | CDN | AVCODES |
| 2 | PTO | Pilot Training Network GmbH | Callsign: Rookie, | D | AVCODES |
| 3 | PTO | North West Geomatics | | | ICAO1 |
| 4 | PTO | PORTLAND TERMINAL (OREGON) | | | PWRC |
| 5 | PTOA | PENISNULA TRANSPORT INC | | | SCAC3 |
| 6 | PTOB | PACIFIC TOWBOAT & SALVAGE CO | | | SCAC3 |
| 7 | PTOC | PATON RACING | | | SCAC4 |
| 8 | PTOD | PATTERSON OIL CO INC | | | SCAC4 |
| 9 | PTOE | PETRO ENERGY TRANSPORT COMPANY INC | | | SCAC3 |
| 10 | PTOG | PARROTT TRANSPORTATION INC | | | SCAC3 |
| 11 | PTOG | PICTURE THIS ON GRANITE | | | SCAC4 |
| 12 | PTOH | PORT OF HOMER | | | SCAC3 |
| 13 | PTOH | PATRIOT TRUCKING & OIL LLC | | | SCAC4 |
| 14 | PTOI | PAL TRANSPORT INC | | | SCAC3 |
| 15 | PTOI | PETILLO INC | | | SCAC4 |
| 16 | PTOJ | PRIMO TRANSPORT INC | | | SCAC3 |
| 17 | PTOK | PILATO TRUCKING | | | SCAC3 |
| 18 | PTOK | PIERCE, TOM TRUCKING | | | SCAC4 |
| 19 | PTOL | PAPER TRANSPORT LTD | | | SCAC3 |
| 20 | PTOL | PAPER TRANSPORT LTD | | | SCAC4 |
| 21 | PTOM | PATTONS MOVERS INC | | | SCAC3 |
| 22 | PTON | PETRINO, NORMAN | | | SCAC4 |
| 23 | PTOO | PIERCE TRANSPORTATION | | | SCAC3 |
| 24 | PTOP | PETRO OIL CO INC | | | SCAC4 |
| 25 | PTOQ | PITTCO DELIVERY | | | SCAC3 |
| 26 | PTOQ | POOK TOQUE | | | SCAC4 |
| 27 | PTOS | POTOSI EXPRESS | | | SCAC3 |
| 28 | PTOT | PLATINUM TOOL TECHNOLOGIES | | | SCAC4 |
| 29 | PTOU | PETRA OIL DMCC | | UAE | BIC |
| 30 | PTOW | PREFERRED TOWING | | | SCAC4 |
| 31 | PTOX | PTO Rail, Inc. | 7/2005 (not listed) | | NAKINA |
| 32 | PTOX | PTO, Inc. | added 4/1986; 1/1994-7/2000; eliminated 7/2004 | | NAKINA |
| 33 | PTOX | Pittsburgh-Texas Oil and Gas Co. | 8/1920 | | NAKINA |
| 34 | PTOX | PTO, Inc. | added 4/86; 1/94-7/2000 | | NRHS |
| 35 | PTOX | *PITTSBURGH-TEXAS OIL & GAS CO. | | | PWRC |
| 36 | PTOX | +PTO RAIL, INC. [PTO INCORPORATED] | | | PWRC |
| 37 | PTOX | PTO Rail | | | RSRV |
| 38 | PTOX | PTO RAIL LLC | | | SCAC4 |
| 39 | PTOY | POTTER OIL CO INC | | | SCAC4 |
| 40 | PTOZ | PORT OF TACOMA | | | PWRC |
