| 1 | ACY | Air City SA | IATA: CE, Callsign: Air City, | CH | AVCODES |
| 2 | ACY | Archana Airways Ltd. | IATA: F5, Callsign: Archana, Founded on 29 April 1991. Commenced operations in 1993. Ceased operations during 2000. | IND | AVCODES |
| 3 | ACY | Atlantic Southeast Airlines, Inc. | IATA: EV, Callsign: Acey, IATA Prefix: 862, ICAO designator changed to ASQ. ICAO designator changed from CAA. ICAO callsign change from Candler. ICAO designator changed from ASE | USA | AVCODES |
| 4 | ACY | Atlas Cargo Airlines | Callsign: Atlas Cargolines, | MA | AVCODES |
| 5 | ACY | Armenian National Airlines CLSC d/b/a FLY ARNA | IATA: G6, Callsign: Arna, IATA Prefix: 253, Planned national airline. A joint venture company between the Armenian National Interests Fund (ANIF) and Air Arabia Group. Air Operating Certificate (AOC) and Air Operator License (AOL) granted 03/06/2022. | AM | AVCODES |
| 6 | ACY | Atlas Cargo Lines | | | ICAO1 |
| 7 | ACY | Norfolk Southern Ry. Co. | added 1/1991; 1/1994-7/2005 | | NAKINA |
| 8 | ACY | Norfolk and Western Railway Co. | added 1/1977; 1/1980-1/1985; eliminated 1/1991 | | NAKINA |
| 9 | ACY | Akron, Canton & Youngstown R.R. Co. | 4/1938-1/1975; eliminated 1/1977; eliminated 1/1982 | | NAKINA |
| 10 | ACY | Akron, Canton & Youngstown R.R. Co. | 4/38-1/75; eliminated 1/77; eliminated 1/82 | | NRHS |
| 11 | ACY | Norfolk and Western Railway Co. | added 1/77; 1/80; eliminated 1/91 | | NRHS |
| 12 | ACY | Norfolk Southern Ry. Company | added 1/91; 1/94-7/2000 | | NRHS |
| 13 | ACY | NORFOLK SOUTHERN [AKRON, CANTON & YOUNGSTON RAILROAD; NORFOLK & WESTERN RY.] | | | PWRC |
| 14 | ACY | Akron, Canton and Youngstown Railroad (Norfolk Southern Railway) | | | RSRV |
| 15 | ACY | Akron, Canton & Youngstown Railroad | | USA | TRAFFIC |
| 16 | ACYA | ALLEGANY COUNTY TRANSIT AUTHORITY | | | SCAC3 |
| 17 | ACYA | ACADIAN DRIVEWAY | | | SCAC4 |
| 18 | ACYB | ACADEMY BULK TRANSPORTATION INC | | | SCAC3 |
| 19 | ACYC | AMERICAN RECYCLING | | | SCAC4 |
| 20 | ACYD | ACE CITY CARTAGE | | | SCAC4 |
| 21 | ACYE | AMERICAN COMMODITY EXPRESS INC | | | SCAC3 |
| 22 | ACYF | AIR-CITY INC | | | SCAC4 |
| 23 | ACYG | AMERICAN CARRIER GROUP INC (DIVISIO | | | SCAC3 |
| 24 | ACYG | AMERICAN CARRIER GROUP INC (DIVISIO | | | SCAC4 |
| 25 | ACYH | ATLANTIC COAST ENERGY LLC | | | SCAC4 |
| 26 | ACYI | ACCENT INTERNATIONAL INC | | | SCAC3 |
| 27 | ACYI | ACE CITY INC | | | SCAC4 |
| 28 | ACYK | ATLAS CARTAGE COMPANY | | | SCAC4 |
| 29 | ACYL | ALL CITY TRUCKING & LEASING | | | SCAC3 |
| 30 | ACYM | ALLAN CO | | | SCAC3 |
| 31 | ACYO | ACTION COURIER SERVICE INC | | | SCAC3 |
| 32 | ACYP | ACADEMY TRANSPORT INC | | | SCAC3 |
| 33 | ACYQ | ACROSS COUNTRY TRANSPORT | | | SCAC4 |
| 34 | ACYR | ALL CITY TRAILER REPAIR INC | | | SCAC3 |
| 35 | ACYR | ARTISANAT RICHARD CYR ET FILS INC | | | SCAC4 |
| 36 | ACYS | ACCEL COURIER SYSTEMS INC | | | SCAC3 |
| 37 | ACYS | AMERICA CARGO LOGISTIC INC | | | SCAC4 |
| 38 | ACYT | ATLANTIC CITY TOURS INC | | | SCAC3 |
| 39 | ACYU | ACS SYSTEMS LIMITED | | HK | BIC |
| 40 | ACYV | ACADEMY VAN LINES INC | | | SCAC3 |
| 41 | ACYW | ATLC | | | SCAC4 |
| 42 | ACYX | AMERICAN CYANAMID CO | | | SCAC3 |
| 43 | ACYY | ADESA CALGARY | | | SCAC4 |
