| 1 | ACO | Air Columbia | IATA: 9X, Callsign: Spada, Name changed to Transporti Aerei Italiani S.r.l. | I | AVCODES |
| 2 | ACO | Transporti Aerei Italiani S.r.l. | IATA: 9X, Callsign: Spada, ICAO designator changed to ACL. Name changed from Air Columbia | I | AVCODES |
| 3 | ACO | Aero Comondu, S.A. de C.V. | Callsign: Aero Comondu, | MEX | AVCODES |
| 4 | ACO | Multi-Aero, Inc. d/b/a Air Choice One | IATA: 3E, Callsign: Weber, ICAO designator changed from WBR w.e.f. 01 Febraury 2019. Name changed from Multi-Aero, Inc. Merged into Southern Airways Express (9X/FDY). | USA | AVCODES |
| 5 | ACO | Aero Comondu | | | ICAO1 |
| 6 | ACOA | AMERICA CARGO TRANSPORT CORP | | | SCAC4 |
| 7 | ACOB | ACORN BUILDING COMPONENTS INC | | | SCAC3 |
| 8 | ACOC | ANDERSON, A COURIER & TRANSPORTATIO | | | SCAC3 |
| 9 | ACOD | ANCOR TRANSPORT LTD | | | SCAC4 |
| 10 | ACOE | A C OERSSLEFFS EFTF A/S | | | SCAC4 |
| 11 | ACOE | American Coal Enterprises | | USA | TRAFFIC |
| 12 | ACOF | ACORN FORWARDING INC | | | SCAC3 |
| 13 | ACOH | AEROPRES CORPORATION | | | SCAC4 |
| 14 | ACOI | ALL COAST TRANSPORT CORP | | | SCAC3 |
| 15 | ACOJ | ACORN TRANSPORT CO | | | SCAC3 |
| 16 | ACOK | ACE TRANSFER & STORAGE | | | SCAC3 |
| 17 | ACOL | ALERT COACH LINES INC | | | SCAC3 |
| 18 | ACOL | ACT CARRIERS LLC | | | SCAC4 |
| 19 | ACOM | ACTION MOVING & STORAGE INC | | | SCAC3 |
| 20 | ACOM | AUTO TRANSPORTES COMANCHE S A DE C | | | SCAC4 |
| 21 | ACOO | ALLAN COMPANY | | | SCAC3 |
| 22 | ACOO | ALLAN COMPANY | | | SCAC4 |
| 23 | ACOP | ACTION TRANSIT COMPANY | | | SCAC3 |
| 24 | ACOQ | AIRCO TRUCKING (A DIV OF THE BOC GR | | | SCAC3 |
| 25 | ACOQ | AASP INC OF COLORADO | | | SCAC4 |
| 26 | ACOR | ATL CORPORATION | | | SCAC3 |
| 27 | ACOR | ACRO INC | | | SCAC4 |
| 28 | ACOS | ACCORD SERVICES, INC. | | | SCAC3 |
| 29 | ACOT | ACOTRAL | Roma - Ostia Lido | I | TRAFFIC |
| 30 | ACOU | COMPAÑIA LOGISTICA ACOTRAL, S.A.U. | | E | BIC |
| 31 | ACOU | ASSOCIATED OCTEL CO., LTD. | | | PWRC |
| 32 | ACOU | Associated Octel | | | RSRV |
| 33 | ACOU | ACO BV | | | SCAC4 |
| 34 | ACOV | ACOMA VAN & STORAGE | | | SCAC3 |
| 35 | ACOV | ACOMA VAN & STORAGE | | | SCAC4 |
| 36 | ACOW | AUTO CONNECTIONS INC | | | SCAC3 |
| 37 | ACOW | ARCADIA COOPERATIVE ASSOCIATION | | | SCAC4 |
| 38 | ACOX | Chrysler Rail Transportation Corp. | added 1/1990; 1/1994 (not listed); eliminated 1/1997 | | NAKINA |
| 39 | ACOX | Aurora Cooperative Elevator Co. | added 10/1970; 1/1975-1/1985; eliminated 1/1990 | | NAKINA |
| 40 | ACOX | Wright Chemical Corp. | added 1/1965; 7/1965-10/1966; eliminated 1/1967 | | NAKINA |
| 41 | ACOX | American Cotton Oil Co. | 8/1920-7/1923 | | NAKINA |
| 42 | ACOX | Wright Chemical Corp. | added 1/65; 7/65-10/66; eliminated 1/67 | | NRHS |
| 43 | ACOX | Aurora Cooperative Elevator Co. | added 10/70; 1/75-1/80; eliminated 1/90 | | NRHS |
| 44 | ACOX | Chrysler Rail Transportation Corp. | added 1/90; 1/94; eliminated 1/97 | | NRHS |
| 45 | ACOX | *AMERICAN COTTON OIL CO. | | | PWRC |
| 46 | ACOX | *WRIGHT CHEMICAL CORP. | | | PWRC |
| 47 | ACOX | *AURORA COOPERATIVE ELEVATOR CO | | | PWRC |
| 48 | ACOX | *CHRYSLER RAIL TRANSPORTATION CORPORATION | | | PWRC |
| 49 | ACOX | Aurora Cooperative Elevator | | | RSRV |
| 50 | ACOX | WRIGHT CHEMICAL CORP | | | SCAC3 |
| 51 | ACOZ | AMERICAN COLLOID CO. | | | PWRC |
