| 1 | B | Bamberger R.R. | 1/1941-7/1965 | | NAKINA |
| 2 | B | Bamberger R.R. | 1/52-7/65 | | NRHS |
| 3 | B | BAMBERGER RR | | | PWRC |
| 4 | B | NMBS/SNCB | | BE | VKM |
| 5 | B&A | Boston & Albany R.R. | 8/1920-10/1966 | | NAKINA |
| 6 | B&A | Boston & Albany R.R. | 7/23-10/66 | | NRHS |
| 7 | B&A | CONSOLIDATED RAIL CORP. [BOSTON & ALBANY RR] | | | PWRC |
| 8 | B&C | Barre & Chelsea R.R. Co. | 7/1923-1/1946 | | NAKINA |
| 9 | B&C | Barre & Chelsea R.R. Co. | 23-Jul | | NRHS |
| 10 | B&C | BARRE & CHELSEA RAILROAD CO. | | | PWRC |
| 11 | B&CW | Bennettsville & Cheraw R.R. Co. | 8/1920-1/1950 | | NAKINA |
| 12 | B&CW | Bennetsville & Cheraw R.R. Co. | 7/23-4/38 | | NRHS |
| 13 | B&CW | BENNETTSVILLE & CHERAW RAILROAD CO. | | | PWRC |
| 14 | B&G | Bingham & Garfield Ry. Co. | 8/1920-7/1936 | | NAKINA |
| 15 | B&G | Bingham & Garfield Ry. Co. | 23-Jul | | NRHS |
| 16 | B&G | BINGHAM & GARFIELD RWY. CO. | | | PWRC |
| 17 | B&LE | Pittsburgh, Bessemer & Lake Erie R.R. (Bessemer & Lake Erie R.R.) | 8/1920-7/1936 | | NAKINA |
| 18 | B&LE | Bessemer & Lake Erie R.R. | 8/1920-10/1966 | | NAKINA |
| 19 | B&LE | Bessemer & Lake Erie R.R. | 7/23-10/66 | | NRHS |
| 20 | B&LE | BESSEMER & LAKE ERIE RAILROAD | | | PWRC |
| 21 | B&M | Boston and Maine R.R. | 8/1920-7/1936 | | NAKINA |
| 22 | B&M | Boston and Maine R.R. | 23-Jul | | NRHS |
| 23 | B&M | *BOSTON & MAINE CORP. | | | PWRC |
| 24 | B&M | *BROWNSTONE & MIDDLETOWN RAILROAD | | | PWRC |
| 25 | B&O | Baltimore & Ohio R.R. Co. | 4/1938-10/1966 | | NAKINA |
| 26 | B&O | Baltimore & Ohio R.R. Co. | 4/38-10/66 | | NRHS |
| 27 | B&O | CSX TRANSPORTATION, INC. [BALTIMORE & OHIO RR] | | | PWRC |
| 28 | B&S | Baltimore & Ohio R.R. | 4/1938-1/1946 | | NAKINA |
| 29 | B&S | Buffalo & Susquehanna R.R. Corp. (Baltimore & Ohio R.R.) | 7/1932-7/1936 | | NAKINA |
| 30 | B&S | Buffalo & Susquehanna R.R. Corp. | 7/1923-7/1930 | | NAKINA |
| 31 | B&S | Buffalo & Susquehanna R.R. Corp. | 23-Jul | | NRHS |
| 32 | B&S | Baltimore & Ohio R.R. | Apr-38 | | NRHS |
| 33 | B&S | Bahn&Service | Walburg | D | privat-bahn.de |
| 34 | B&S | BUFFALO & SUSQUEHANNA RAILROAD [BALTIMORE & OHIO RR] | | | PWRC |
| 35 | B&SE | Birmingham & Southeastern R.R. | 4/1938-7/1965 | | NAKINA |
| 36 | B&SE | Birmingham & Southeastern R.R. | 4/38-7/65 | | NRHS |
| 37 | B&SE | BIRMINGHAM & SOUTHEASTERN RAILROAD | | | PWRC |
| 38 | B0 | DreamJet SAS d/b/a La Compagnie | ICAO: DJT, Callsign: Dreamjet, IATA Prefix: 002, Commenced operations on 10 July 2014. First Flight 15 July 2014. New all Business Class startup. | F | AVCODES |
| 39 | B1 | CIONS Software Ltda | Designator B1 recalled by IATA. Computer Reservations Systems (CRS) | BR | AVCODES |
| 40 | B1 | Bravo Passenger Solution Pte., Ltd. | Computer Reservations Systems (CRS) | SGP | AVCODES |
| 41 | B1 | JBSS Bahn 1x | | | TRAFFIC |
| 42 | B2 | Belavia | ICAO: BRU, Callsign: Belarus Avia, IATA Prefix: 268, ICAO callsign changed to Belavia | BY | AVCODES |
| 43 | B2 | Belavia | ICAO: BRU, Callsign: Belavia, IATA Prefix: 268, ICAO callsign changed from Belarus Avia | BY | AVCODES |
| 44 | B2 | JBSS Bahn 2x | | | TRAFFIC |
| 45 | B3 | Beliview Airlines Ltd. | ICAO: BLV, Callsign: Bellview Airlines, IATA Prefix: 208, IATA designator changed to B3 | WAN | AVCODES |
| 46 | B3 | Ambassador Airways | ICAO: AMY, Callsign: Ambassador, Ceased operations on 28 November 1994. | GB | AVCODES |
| 47 | B3 | Beliview Airlines Limited | ICAO: BLV, Callsign: Bellview Airlines, IATA Prefix: 208, Ceased operations. IATA designator changed from B3* | WAN | AVCODES |
| 48 | B3 | Tashi Air Private Ltd. t/a Bhutan Airlines | ICAO: BTN, Callsign: Bhutan Air, IATA Prefix: 786, | BTN | AVCODES |
| 49 | B4 | Bankair, Inc. | ICAO: BKA, Callsign: Bankair, Designator B4* recalled by IATA | USA | AVCODES |
| 50 | B4 | B.A.C.H. Flugbetriebs GmbH | ICAO: BCF, Callsign: Bach, Designator B4 recalled by IATA | A | AVCODES |
| 51 | B4 | Globespan Airways Limited t/a Flyglobespan | ICAO: GSM, Callsign: Globespan, IATA Prefix: 060, IATA designator change to Y2 | GB | AVCODES |
| 52 | B4 | ZanAir Limited | ICAO: TAN, Callsign: Zanair, Designator B4 recalled by IATA | EAT | AVCODES |
| 53 | B4 | JBSS Bahn 4x | | | TRAFFIC |
| 54 | B5 | Flightline Limited | ICAO: FLT, Callsign: Flightline, Ceased operations. Designator B5* recalled by IATA | GB | AVCODES |
| 55 | B5 | Amadeus Flugdienst GmbH and Co. KG | | D | AVCODES |
| 56 | B5 | East African Safari Air Express Ltd. | ICAO: EXZ, Callsign: Twiga, IATA Prefix: 305, Designator B5 recalled by IATA | EAK | AVCODES |
| 57 | B5 | Babylon 5 | Scifi film | | TRAFFIC |
| 58 | B6 | Jetblue Airways Corporation | ICAO: JBU, Callsign: Jetblue, IATA Prefix: 279, | USA | AVCODES |
| 59 | B7 | UNI Airways Corporation | ICAO: UIA, Callsign: Glory, IATA Prefix: 525, | RC | AVCODES |
| 60 | B7 | Bond Air Cargo, LLC | ICAO: BCU, Callsign: Bacair, IATA Prefix: 029, IATA Designator changed to U4*. | USA | AVCODES |
| 61 | B8 | Botir Avia | ICAO: BTR, Callsign: Botir-Avia, Ceased operations. | KS | AVCODES |
| 62 | B8 | Eritrean Airlines | ICAO: ERT, Callsign: Eritrean, IATA Prefix: 637, Ceased Operations. | ER | AVCODES |
| 63 | B8 | Italair S.p.A. | ICAO: DRG, Callsign: Italair, Ceased operations 09/2000 | I | AVCODES |
| 64 | B9 | Iran Air Tours Co. | ICAO: IRB, IATA Prefix: 491, Name changed to Iran Airtour Airline. Desigantor B9 reinstated by IATA | IR | AVCODES |
| 65 | B9 | Air Bangladesh (Pvt.) Limited | ICAO: BGD, Callsign: Air Bangla, Founded in 1997. | BD | AVCODES |
| 66 | B9 | Caribbean International Airlines, Inc. | ICAO: CBC, Callsign: Caribair, Desigantor B9 recalled by IATA. Desigantor B9 reinstated by IATA | DOM | AVCODES |
| 67 | B9 | Iran Airtour Airline | ICAO: IRB, IATA Prefix: 491, Name changed to Iran Air Tours Co. Desigantor B9 reinstated by IATA | IR | AVCODES |
| 68 | BA | British Airways P.L.C. | ICAO: BAW, Callsign: Speedbird, IATA Prefix: 125, Formed by the merger of B.E.A and B.O.A.C. | GB | AVCODES |
| 69 | BA | British Overseas Airways Corporation (BOAC) | Callsign: Speedbird, Merged with B.E.A to form British Airways BA/BAW | GB | AVCODES |
| 70 | BA | Consolidated Rail Corp. | added 4/1976; 1/1980-1/1994; eliminated 7/1999 | | NAKINA |
| 71 | BA | Penn Central Transportation Co., Robert W. Blanchette, Richard C. Bond and John H. McArthur, Trustees | eliminated 4/1976 | | NAKINA |
| 72 | BA | Penn Central Transportation Co. | 1/1975 | | NAKINA |
| 73 | BA | Penn Central Transportation Co. | Jan-75 | | NRHS |
| 74 | BA | Penn Central Transportation Co., Robert W. Blanchette, Richard C. Bond and John H. McArthur, Trustees | eliminated 4/76 | | NRHS |
| 75 | BA | Consolidated Rail Corp. | added 4/76; 1/80-1/94; eliminated 7/99 | | NRHS |
| 76 | BA | CONSOLIDATED RAIL CORP. [BOSTON & ALBANY RR; PENN CENTRAL] | | | PWRC |
| 77 | BA | Boston and Albany Railroad (Conrail) | | | RSRV |
| 78 | BA | British Airways | Real: BAW | GB | TRAFFIC |
| 79 | BA&P | Butte, Anaconda & Pacific Ry. | 8/1920-7/1936 | | NAKINA |
| 80 | BA&P | Butte, Anaconda & Pacific Ry. | 23-Jul | | NRHS |
| 81 | BA&P | BUTTE, ANACONDA & PACIFIC RY. | | | PWRC |
| 82 | BAA | Balkan Agro Aviation | Callsign: Balkan Agro, | BG | AVCODES |
| 83 | BAA | Bo-S-Aire Airlines, Inc. | Callsign: Bowman Air, | USA | AVCODES |
| 84 | BAA | Balkan Agro Aviation | | | ICAO1 |
| 85 | BAAA | BUTLER, ARTHUR R | | | SCAC3 |
| 86 | BAAA | BAYMEADOWS MOVING AND STORAGE INC | | | SCAC4 |
| 87 | BAAB | B & A CHARTER TOURS INC | | | SCAC3 |
| 88 | BAAC | BARRON EXPRESS | | | SCAC4 |
| 89 | BAAE | BUDGET AUTO & EQUIPMENT SALES INC | | | SCAC3 |
| 90 | BAAF | BRODERICK AUTO & TRUCK | | | SCAC4 |
| 91 | BAAG | BALLENSKY, ALAN G | | | SCAC3 |
| 92 | BAAH | BRUCE A BOND PETROLEUM LTD | | | SCAC4 |
| 93 | BAAK | BANTA TRUCKING | | | SCAC3 |
| 94 | BAAL | BAR-LYNN STABLES | | | SCAC4 |
| 95 | BAAM | BENSTEAD, A & A TRUCKING LLC | | | SCAC4 |
| 96 | BAAN | BAUR FREIGHT SYSTEMS LLC | | | SCAC4 |
| 97 | BAAO | BROWN & ASSOCIATES INC | | | SCAC3 |
| 98 | BAAP | BARNDT, A PAUL | | | SCAC3 |
| 99 | BAAP | BAR RB LTD | | | SCAC4 |
| 100 | BAAQ | BARABOO ASPHALT COMPANY INC | | | SCAC3 |
