| 1 | PX | Air Niugini Pty Limited d/b/a Air Niugini | ICAO: ANG, Callsign: Niugini, IATA Prefix: 656, Name changed from Air Niugini | PNG | AVCODES |
| 2 | PX | Air Niugini | ICAO: ANG, Callsign: Niugini, IATA Prefix: 656, Name changed to Air Niugini Pty Limited d/b/a Air Niugini | PNG | AVCODES |
| 3 | PX | Pressed Steel Co. Ltd. (Aviation Division) Oxford | Callsign: Prestair, | GB | AVCODES |
| 4 | PX | Union Tank Car Co. | 7/1937-4/1970; eliminated 7/1973 | | NAKINA |
| 5 | PX | Products Tank Line (Union Tank Car Co.) | 7/1930-7/1935 | | NAKINA |
| 6 | PX | Products Tank Line (Union Tank Car Co.) | Apr-38 | | NRHS |
| 7 | PX | Union Tank Car Co. | 1/52-4/70; eliminated 7/73 | | NRHS |
| 8 | PX | UNION TANK CAR CO. [PRODUCTS TANK LINE] | | | PWRC |
| 9 | PXA | Pecotox Air S.r.l. | Callsign: Pecotox, | MD | AVCODES |
| 10 | PXA | Pan Am II | IATA: PA, Callsign: Clipper, Ceased operations on 26 February 1998. | USA | AVCODES |
| 11 | PXA | Pecotox Air | | | ICAO1 |
| 12 | PXAL | PHOENIX AG-LINES | | | SCAC3 |
| 13 | PXAN | PRICE TRAN LLC | | | SCAC4 |
| 14 | PXAP | PIXA PRINTING | | | SCAC4 |
| 15 | PXAR | PRAXAIR SERVICES CANADA INC | | | SCAC4 |
| 16 | PXAU | PRAXAIR ARGENTINA SRL | | | SCAC4 |
| 17 | PXB | Phoenix Air Ltd. | Callsign: Phoenix Bulgaria, | BG | AVCODES |
| 18 | PXBC | PHOENIX BULK CARRIERS (U S) CORP | | | SCAC4 |
| 19 | PXC | Palau Express Airlines Corporation | IATA: P9, Callsign: Palau Express, | PAL | AVCODES |
| 20 | PXCI | PAXICON INC | | | SCAC3 |
| 21 | PXCI | PAXICON INC | | | SCAC4 |
| 22 | PXCN | PUMPERNICK | | | SCAC4 |
| 23 | PXCO | PHOENIX-COASTAL INC | | | SCAC3 |
| 24 | PXCR | PRIORITY EXPRESS COURIER INC | | | SCAC4 |
| 25 | PXCU | KAWASAKI KISEN KAISHA LTD - K LINE | | J | BIC |
| 26 | PXCU | PHOENIX CONTAINER LINERS LTD. | | | PWRC |
| 27 | PXCU | Phoenix Container Liners Limited | | | RSRV |
| 28 | PXCU | K LINE (KAWASAKI KISEN KAISHA LTD) | | | SCAC3 |
| 29 | PXCU | KAWASAKI KISEN KAISHA LTD | | | SCAC4 |
| 30 | PXCZ | (PXCU) PHOENIX CONTAINER LINERS LTD. | | | PWRC |
| 31 | PXCZ | Phoenix Container Liners Limited | | | RSRV |
| 32 | PXCZ | K LINE (KAWASAKI KISEN KAISHA LTD) | | | SCAC3 |
| 33 | PXCZ | PHOENIX CONTAINER LINERS LTD. | | | SCAC4 |
| 34 | PXDI | PHOENIX DELIVERY SERVICE | | | SCAC3 |
| 35 | PXDI | PUTNAM EXPRESS | | | SCAC4 |
| 36 | PXDL | PAX DISTRIBUTION LLC | | | SCAC4 |
| 37 | PXEI | PARKERS EXPRESS INC | | | SCAC4 |
| 38 | PXEP | PHOENIX EXPRESS INC | | | SCAC3 |
| 39 | PXEP | PENIX TRANSPORT | | | SCAC4 |
| 40 | PXEV | PTES | | | SCAC4 |
| 41 | PXG | Aitheras Aviation Group, LLC | Callsign: Phoenix Global, | USA | AVCODES |
| 42 | PXIF | PRINCIPAL TRANSPORT INC OF FLORIDA | | | SCAC4 |
| 43 | PXIK | PX INC | | | SCAC4 |
| 44 | PXIL | PORT TRANSPORT INTERMODAL | | | SCAC4 |
| 45 | PXIN | PRIDE EXPRESS INC | | | SCAC4 |
| 46 | PXIS | PXI | | | SCAC4 |
| 47 | PXJ | Jet Team, Inc | Callsign: Phoenix Jet, | USA | AVCODES |
| 48 | PXLC | PERFORMANCE TRANSPORT LLC | | | SCAC4 |
| 49 | PXME | PROMOTEX INC | | | SCAC4 |
| 50 | PXMN | PRIMEM | | | SCAC4 |
| 51 | PXNL | PAXTON, LLOYD | | | SCAC4 |
| 52 | PXNP | POLITE TRANSPORTATION | | | SCAC4 |
| 53 | PXNS | PREMIUM CARRIERS LLC | | | SCAC4 |
| 54 | PXNV | PRIME TRANSPORTATION SERVICES | | | SCAC4 |
| 55 | PXP | Pacific air Transport, Inc. | Callsign: Pak Express, | USA | AVCODES |
| 56 | PXP | Pacific Air Transport | | | ICAO1 |
| 57 | PXPA | PRESS X-PRESS INC | | | SCAC3 |
| 58 | PXPA | POLLY EXPRESS INC | | | SCAC4 |
| 59 | PXPC | PRONTO EXPRESS COMPANY | | | SCAC3 |
| 60 | PXPC | PACKAGE EXPRESS | | | SCAC4 |
| 61 | PXPE | PTH EXPRESS INC | | | SCAC4 |
| 62 | PXPF | PRESTON EXPRESS LLC | | | SCAC4 |
| 63 | PXPG | PACEX PACKAGE EXPRESS INC | | | SCAC4 |
| 64 | PXPH | PHOENIX ENERGY NAVIGATION SA | | | SCAC4 |
| 65 | PXPI | PRINTERS EXPRESS INC | | | SCAC3 |
| 66 | PXPJ | PTL XPRESS | | | SCAC4 |
| 67 | PXPK | PRIORITY DISPATCH INC | | | SCAC4 |
| 68 | PXPL | PANOTEX PIPE LINE COMPANY | | | SCAC3 |
| 69 | PXPM | PAXPORT MILLS INC | | | SCAC3 |
| 70 | PXPO | PRONTO EXPRESS | | | SCAC4 |
| 71 | PXPP | PAUL XPRESS | | | SCAC4 |
| 72 | PXPQ | PRATTS EXPRESS CO | | | SCAC3 |
| 73 | PXPQ | PROPANE EXPRESS INC | | | SCAC4 |
| 74 | PXPR | PIEDMONT EXPRESS INC | | | SCAC3 |
| 75 | PXPR | PROLINE XPRESS INC | | | SCAC4 |
| 76 | PXPS | PREMIER EXPEDITED SERVICES INC | | | SCAC4 |
| 77 | PXPT | PENGUIN EXPRESS TRUCKING INC | | | SCAC3 |
| 78 | PXPV | PRO TECH EXTERIOR PRODUCTS LTD | | | SCAC4 |
| 79 | PXPW | PHOENIX SHIPHOLDING CORP | | | SCAC4 |
| 80 | PXR | Pixair Survey | Callsign: Pixair, | F | AVCODES |
| 81 | PXRI | PETRO EXPRESS INC | | | SCAC4 |
| 82 | PXRU | PRAXAIR PERU SRL | | | SCAC4 |
| 83 | PXS | Boston-Maine Airways | Callsign: Panam Express, ICAO Designator and Callsign changed to CXS / Clipper Express | USA | AVCODES |
| 84 | PXSH | PINNIX, STEVE HAULING CORP | | | SCAC3 |
| 85 | PXSL | PREMIER TRANSPORT SERVICES LLC | | | SCAC4 |
| 86 | PXSS | PERSONAL TRANSPORATTION SERVICES | | | SCAC4 |
| 87 | PXT | Pacific Coast Jet | Callsign: Pack Coast, | USA | AVCODES |
| 88 | PxT | Proxion Train Oy | | FI | VKM |
| 89 | PXTG | PORT XPRESS TRUCKING | | | SCAC4 |
| 90 | PXTI | PHOENIX TOURS INTERNATIONAL INC | | | SCAC3 |
| 91 | PXTL | PAXTON TRANSPORT LTD | | | SCAC3 |
| 92 | PXTL | PERRETE TRANSFER IMPORTACION EXPORT | | | SCAC4 |
| 93 | PXTN | PROEX LOGISTICS LLC | | | SCAC4 |
| 94 | PXTP | PON X TRANSPORT | | | SCAC3 |
| 95 | PXTQ | PHOENIX TRANSPORT SYSTEMS INC | | | SCAC4 |
| 96 | PXTR | PAXTON TRUCK LINES | | | SCAC3 |
| 97 | PXTR | POLO EXPRESS TRANSPORTATION | | | SCAC4 |
| 98 | PXTW | PHOENIX TANKERS PTE LTD | | | SCAC4 |
| 99 | PXX | Aroostook Aviation, Inc. | Callsign: Pine State, | USA | AVCODES |
| 100 | PXX | Pan Am Express | IATA: RZ, Callsign: Pan Am, Ceased operations | USA | AVCODES |
