| T3 | EZE | 467 | Eastern Airways |
| T4 | TRL | 609 | TransEast Airlines |
| T4 | HEJ | 681 | Hellas Jet |
| T5 | TUA | 542 | Turkmenistan Airlines |
| T6 | TVR | 204 | Tavrey Aircompany |
| T7 | TLA | 839 | Transaer |
| T8 | STA | STA Trans African Airlines | |
| T9 | TRZ | TransMeridian Airlines | |
| TA | TAI | 202 | TACA International Airlines/Groupo TACA |
| TC | ATC | 197 | Air Tanzania |
| TD | Trans European Airways Italia | ||
| TE | LIL | 874 | flyLAL - Lithuanian Airlines |
| TF | SCW | 276 | Malmö Aviation |
| TG | THA | 217 | Thai Airways |
| TH | 259 | LAR Transregional | |
| TH | TSE | 539 | Transmile Air Services |
| TI | BIA | Baltic International Airlines | |
| TI | TOL | Tol Air Services | |
| TJ | TZK | Tajikistan International Airlines | |
| TJ | SBE | Sabre Airways | |
| TK | THY | 235 | Turkish Airlines |
| TL | TMA | 270 | Trans Mediterranean Airways |
| TL | ANO | 935 | Airnorth Regional |
| TM | LAM | 068 | LAM-Linhas Aereas de Mozambique |
| TN | THT | 244 | Air Tahiti Nui |
| TO | TRT | TAAT-Trans Arabian Air Transport | |
| TO | PSD | 540 | President Airlines |
| TP | TAP | 047 | TAP-Air Portugal |
| TQ | TWE | 227 | Transwede Airways AB |
| TQ | TDM | 038 | Tandem Aero |
| TR | TBA | 653 | Transbrasil SA Linhas Aereas/Interbrasil Star |
| TR | TGW | Tiger Airways | |
| TS | TSC | 649 | Air Transat |
| TT | KLA | 843 | Air Lithuania |
| TU | TAR | 199 | Tunisair |
| TV | VEX | 665 | Virgin Express |
| TW | TWA | 015 | Trans World Airlines |
| TX | FWI | Air Caraibes | |
| TY | BCM | BCM Airlines SA | |
| TY | GJB | 348 | Trans Air Link |
| TZ | AMT | 366 | American Trans Air |