| 1 | P&E | Consolidated Rail Corp. | added 4/1976 | | NAKINA |
| 2 | P&E | Penn Central Transportation Co., Robert W. Blanchette, Richard C. Bond and John H. McArthur, Trustees | eliminated 4/1976 | | NAKINA |
| 3 | P&E | Penn Central Transportation Co., Robert W. Blanchette, Richard C. Bond and John H. McArthur, Trustees | eliminated 4/76 | | NRHS |
| 4 | P&E | Consolidated Rail Corp. | added 4/76 | | NRHS |
| 5 | P&E | CONSOLIDATED RAIL CORP. [PENN CENTRAL TRANSPORTATION CO.; PEORIA & EASTERN RY.] | | | PWRC |
| 6 | P&IN | Pacific and Idaho Northern Ry. (Co.) | 8/1920-7/1936 | | NAKINA |
| 7 | P&IN | PACIFIC & IDAHO NORTHERN RWY. | | | PWRC |
| 8 | P&LE | PITTSBURGH & LAKE ERIE RAILROAD (NOW CSX TRANSPORTATION) | | | PWRC |
| 9 | P&MP | Paris & Mt. Pleasant R.R. Co. | 8/1920-7/1936 | | NAKINA |
| 10 | P&MP | PARIS & MT. PLEASANT RAILROAD CO. | | | PWRC |
| 11 | P&N | Seaboard Coast Line R.R. Co. | eliminated 4/1975 | | NAKINA |
| 12 | P&N | Seaboard Coast Line R.R. Co. | eliminated 4/75 | | NRHS |
| 13 | P&N | SEABOARD COAST LINE RAILROAD CO. [PIEDMONT & NORTHERN RWY.] | | | PWRC |
| 14 | P&NW | (The) Prescott & Northwestern R.R. (Co.) | 7/1923-10/1966 | | NAKINA |
| 15 | P&NW | Prescott & Northwestern R.R. | 4/38-10/66 | | NRHS |
| 16 | P&NW | PRESCOTT & NORTHWESTERN RAILROAD CO. | | | PWRC |
| 17 | P&OV | Pittsburgh & Ohio Valley Ry. | 4/1938-10/1966 | | NAKINA |
| 18 | P&OV | Pittsburgh & Ohio Valley Ry. Co. | 7/1923-7/1936 | | NAKINA |
| 19 | P&OV | Pittsburgh & Ohio Valley Ry. | 4/38-10/66 | | NRHS |
| 20 | P&OV | PITTSBURGH & OHIO VALLEY RAILWAY CO. | | | PWRC |
| 21 | P&PU | Peoria & Pekin Union Ry. | 8/1920-4/1970 | | NAKINA |
| 22 | P&PU | Peoria & Pekin Union Ry. | 4/38-4/70 | | NRHS |
| 23 | P&PU | PEORIA & PEKIN UNION RAILWAY CO. | | | PWRC |
| 24 | P&R | Philadelphia & Reading Ry. Co. (Reading Co.) | 7/1930-7/1936 | | NAKINA |
| 25 | P&R | Philadelphia & Reading Ry. Co. | 8/1920-7/1923 | | NAKINA |
| 26 | P&R | READING CO. [PHILADELPHIA & READING RAILWAY CO.] | | | PWRC |
| 27 | P&SR | Petaluma & Santa Rosa R.R. | 4/1938-4/1970 | | NAKINA |
| 28 | P&SR | Petaluma & Santa Rosa R.R. | 4/38-4/70 | | NRHS |
| 29 | P&SR | PETALUMA & SANTS ROSA RAILROAD CO. | | | PWRC |
| 30 | P&WRR | PIEDMONT & WESTERN RAILROAD CLUB (OLD ROCK SCHOOL RAILWAY MUSEUM) | | | PWRC |
| 31 | P&WV | Norfolk and Western Ry. Co. | 10/1966 | | NAKINA |
| 32 | P&WV | Pittsburgh & West Virginia Ry. (Norfolk and Western Ry.) | 4/1970 | | NAKINA |
| 33 | P&WV | (The) Pittsburgh & West Virginia Ry. (Co.) | 8/1920-7/1965 | | NAKINA |
| 34 | P&WV | PITTSBURGH & WEST VIRGINIA RY (NOW NORFOLK SOUTHERN RAILWAY) | | | PWRC |
| 35 | P0 | Proflight Commuter Services Limited | ICAO: PFZ, Callsign: Proflight-Zambia, | Z | AVCODES |
| 36 | P0 | Proflight Commuter Services Limited | ICAO: PFZ, Callsign: Proflight-Zambia, | Z | AVCODES |
| 37 | P1 | Aviation Technologies Inc. d/b/a PublicCharters.com | Name changed to Public Charters, Inc. d/b/a REGIONAL Sky. Computer Reservations Systems (CRS) | USA | AVCODES |
| 38 | P1 | Public Charters, Inc. d/b/a REGIONAL Sky | IATA designator changed to 4P. Name changed from Aviation Technologies Inc. d/b/a PublicCharters.com | USA | AVCODES |
| 39 | P2 | Tyumenavyatrans Aviation Joint-Stock Company | ICAO: TMN, Callsign: Tjumavi, IATA Prefix: 298, Name changed from Joint Stock Air Carrier Company Tjumenaviatrans. IATA designator changed from 7M | RUS | AVCODES |
| 40 | P2 | Aero-Cóndor, S.A. | ICAO: CDP, Founded in 1975. IATA designator changed to Q6. | PE | AVCODES |
| 41 | P2 | Joint Stock Air Carrier Company Tjumenaviatrans | ICAO: TMN, Callsign: Tjumavi, Name changed to Tyumenavyatrans Aviation Joint-Stock Company. IATA designator changed from 7M | RUS | AVCODES |
| 42 | P2 | Tyumenaviatrans Joint Stock Air Carrier Company | ICAO: TMN, Name changed to Tyumenavyatrans Aviation Joint-Stock Company | RUS | AVCODES |
| 43 | P2 | Panair S.p.A. | ICAO: PIT, Callsign: Panairfly, Name changed from Panair - Comagnia Aerea Mediterranea Srl. Name changed from Panair - Comagnia Aerea Meridiaonale Srl | I | AVCODES |
| 44 | P2 | Utair Aviation Joint-Stock Company | ICAO: TMN, Callsign: Tjumavi, IATA Prefix: 298, IATA desigantor changed to UT. Name changed from Tyumenavyatrans Aviation Joint-Stock Company. Name changed from Joint Stock Air Carrier Company Tjumenaviatrans | RUS | AVCODES |
| 45 | P2 | Airkenya Express Ltd. | ICAO: XAK, IATA Prefix: 853, IATA Designator changed from QP. Designator reinstated by P2 IATA. Name changed from Airkenya Aviation Ltd. d/b/a Regional Air. Formerly Airkenya Aviation Ltd. | EAK | AVCODES |
| 46 | P2 | Small Planet Airlines Italia | ICAO: LLI, Callsign: Auriga, Operating Licence suspended by Italian Civil Aviation Authority (ENAC) on 20 January 2014. | I | AVCODES |
| 47 | P3 | Premier Trans Aire, Inc. | IATA Prefix: 435, IATA Designator changed to 3X* | USA | AVCODES |
| 48 | P3 | Phoenix Aviation Air Company | ICAO: PHG, Callsign: Phoenix Group, Designator P3 recalled by IATA | KS | AVCODES |
| 49 | P3 | Passaredo Transportes Aereos, S.A. | ICAO: PTB, Callsign: Passaredo, IATA designator changed to 2Z | BR | AVCODES |
| 50 | P3 | Cargologicair Ltd. | ICAO: CLU, Callsign: Firebird, IATA Prefix: 560, Ceased operations on 24 February 2020. AOC Reinstated on 22/04/2020. Part of Volga-Dnepr Group. | GB | AVCODES |
| 51 | P3 | Porter Airlines Inc. | ICAO: POE, IATA Designator changed from PD. | CDN | AVCODES |
| 52 | P4 | Aerolineas Sosa, S.A. | ICAO: NSO, Callsign: Sosa, Desginator P4* reinstated byIATA | HN | AVCODES |
| 53 | P4 | Air Peace Limited | ICAO: APK, Callsign: Peace Bird, | WAN | AVCODES |
| 54 | P5 | AeroRepública, S.A. | ICAO: RPB, Callsign: Aerorepublica, IATA Prefix: 845, Name changed to Aero Republica, S.A. t/a Copa Airlines Colombia w.e.f. October 2010. Designator P5 reinstated by IATA | CO | AVCODES |
| 55 | P5 | Taxi Fly Group S.A. | ICAO: JPR, Designator P5* recalled by IATA | E | AVCODES |
| 56 | P5 | AeroRepública, S.A. t/a Copa Airlines Colombia | ICAO: RPB, Callsign: Aerorepublica, IATA Prefix: 845, Name changed to AeroRep�blica, S.A. t/a wingo. Name changed from Aero Republica, S.A. Designator P5 reinstated by IATA | CO | AVCODES |
| 57 | P5 | AeroRepública, S.A. t/a wingo | ICAO: RPB, Callsign: Aerorepublica, IATA Prefix: 845, Name changed from Copa Airlines Colombia and previously from Aero Republica, S.A. Designator P5 reinstated by IATA | CO | AVCODES |
| 58 | P6 | Pascan Aviation Inc. | ICAO: PSC, Callsign: Pascan, Name changed to 9736140 Canada Inc. t/a Pascan | CDN | AVCODES |
| 59 | P6 | Trans Air | ICAO: MUI, Callsign: Maui, IATA Prefix: 356, Designator P6 recalled by IATA | USA | AVCODES |
| 60 | P6 | Privilege Style Lineas Aereas S.A. | ICAO: PVG, Callsign: Privilege, IATA Prefix: 433, | E | AVCODES |
| 61 | P6 | Primera Air Scandinavia A/S | ICAO: PRI, Callsign: Primera, IATA Designator changed to PF | DK | AVCODES |
| 62 | P6 | 9736140 Canada Inc t/a Pascan | ICAO: PSC, Callsign: Pascan, Name changed from Pascan Aviation Inc. | CDN | AVCODES |
| 63 | P7 | Joint-Stock Company East Line Airlines | ICAO: ESL, Callsign: Eastline Express, IATA Prefix: 215, Name changed to Russian Sky Airlines JSC. Name changed from Joint-Stock Company East Line Air | RUS | AVCODES |
| 64 | P7 | Joint-Stock Company East Line Air | ICAO: ESL, Callsign: Eastline Express, IATA Prefix: 215, Name changed to Joint-Stock Company East Line Airlines | RUS | AVCODES |
| 65 | P7 | Russian Sky Airlines JSC | ICAO: ESL, Callsign: Eastline Express, IATA Prefix: 215, Name changed from Joint-Stock Company East Line Airlines. Name changed from Joint-Stock Company East Line Air | RUS | AVCODES |
| 66 | P7 | Aero Regional Paraguaya S.A. | ICAO: REP, Callsign: Regiopar, Name changed to Aero Sur Paraguay S.A. ICAO designator changed to AES. | PY | AVCODES |
| 67 | P7 | Small Planet Airlines Sp. z.o.o. | ICAO: LLP, Callsign: Skypol, Ceased operations on 09 November 2018. Name changed from FlyLAL Charters Polksa | PL | AVCODES |
| 68 | P7 | Palau Airways Corp | ICAO: PAU, Callsign: Palauairways, IATA Prefix: 389, Founded in 2011. Ceased operations in April 2013. | PAL | AVCODES |
| 69 | P8 | Pak West Airlines, Inc. d/b/a Sierra West Airlines | ICAO: PKW, Callsign: Platinum West, Designator P8* recalled by IATA. | USA | AVCODES |
| 70 | P8 | IAS International Services GmbH | Designator P8* recalled by IATA. Non-Airline Unit Load Devices (ULD) company | D | AVCODES |
| 71 | P8 | Mekong Aviation JSC (Air Mekong) | ICAO: MKG, Callsign: Air Mekong, IATA Prefix: 819, Ceased operations on 01 March 2013. AOC revoked January 2015. ICAO callsign changed from Mekong | VN | AVCODES |
| 72 | P8 | Mekong Aviation JSC (Air Mekong) | ICAO: MKG, Callsign: Mekong, IATA Prefix: 819, ICAO callsign changed to Air Mekong | VN | AVCODES |
| 73 | P8 | SprintAir SA | ICAO: SRN, Callsign: Sprintair, IATA designator changed from HS*. Founded in 2003. | PL | AVCODES |
| 74 | P88T | 88 Transit | City: Pittsburgh | US-PA | TRAFFIC |
| 75 | P9 | Perm State Air Enterprise | ICAO: PGP, Callsign: Perm Air, Designator P9* recalled by IATA | RUS | AVCODES |
| 76 | P9 | Aero Micronesia Inc d/b/a Asia Pacific Airlines | ICAO: MGE, Callsign: Magellan, IATA Prefix: 046, | GUM | AVCODES |
| 77 | P9 | Pro Air, Inc. | ICAO: PRH, Callsign: Prohawk, Ceased operations on 18 September 2000. IATA desigantor changes from XL* | USA | AVCODES |
| 78 | P9 | Nas Air, S.A. | ICAO: NCM, Callsign: Air Bane, | RMM | AVCODES |
| 79 | P9 | Peruvian Air Lines S.A. | ICAO: PVN, Callsign: Peruvian, Ceased operations on 02 October 2019. | PE | AVCODES |
| 80 | P9 | Palau Express Airlines Corporation | ICAO: PXC, Callsign: Palau Express, | PAL | AVCODES |
| 81 | PA | Florida Coastal Airlines, Inc. | ICAO: FCL, Callsign: Florida Coastal, | USA | AVCODES |
| 82 | PA | Pan American World Airways (Pan-Am) | ICAO: PAA, Callsign: Clipper, Name changed from Pan American Airways in January 1950. Ceased operations on 04 December 1991. | USA | AVCODES |
| 83 | PA | Pan Am II | ICAO: PXA, Callsign: Clipper, Ceased operations on 26 February 1998. | USA | AVCODES |
| 84 | PA | M/S Airblue (PVT) Ltd | ICAO: ABQ, Callsign: Pakblue, IATA Prefix: 084, | PK | AVCODES |
| 85 | PA | Pan American | | USA | TRAFFIC |
| 86 | PA&M | Pittsburgh, Allegheny & McKees Rocks R.R. (Co.) | 7/1923-10/1966 | | NAKINA |
| 87 | PA&M | Pittsburgh, Allegheny & McKees Rocks R.R. | 4/38-10/66 | | NRHS |
| 88 | PA&M | PITTSBURGH, ALLEGHENY & MCKEES ROCKS RAILROAD CO. | | | PWRC |
| 89 | PAA | Pan American Airways Corp. | IATA: PN, Callsign: Clipper, | USA | AVCODES |
| 90 | PAA | Pan American World Airways (Pan-Am) | IATA: PA, Callsign: Clipper, Name changed from Pan American Airways in January 1950. Ceased operations on 04 December 1991. | USA | AVCODES |
| 91 | PAA | Pan American World Airways | IATA: PA | | ICAO1 |
| 92 | PAA | Pan American Airways | IATA: PA | | ICAO1 |
| 93 | PAA | CONSOLIDATED RAIL CORP. [PENNSYLVANIA & ATLANTIC RAILROAD CO.] | | | PWRC |
| 94 | PAA | PORR-ALPINE Austriarail GmbH | | AT | VKM |
| 95 | PAAA | PARRA, ALFONSO | | | SCAC3 |
| 96 | PAAB | P & A TRANSPORT LLC | | | SCAC4 |
| 97 | PAAC | PORT AUTHORITY OF ALLEGHENY COUNTY (PENNSYLVANIA) | | | PWRC |
| 98 | PAAC | PAN AMERICAN CLIPPER PACKAGE SERVIC | | | SCAC4 |
| 99 | PAAE | PALMER, ARTHUR E | | | SCAC4 |
| 100 | PAAF | PILOT AIR FREIGHT CORP | | | SCAC4 |
