| Abbreviation | Definition |
|---|---|
| X21 | Arthur Dunn Air Park Airport, Titusville, Florida USA |
| XAH | Silkeborg, Denmark |
| XAP | Chapeco, SC, Brazil |
| XAR | Arabinda, Burkina Faso |
| XAU | Saul, French Guiana |
| XAY | Xayabury, Laos |
| XAZ | Campbellton Airport, Campbellton, New Brunswick, Canada |
| XBB | Blubber Bay, British Columbia, Canada |
| XBE | Bearskin Lake, Ontario, Canada |
| XBG | Bogande, Burkina Faso |
| XBJ | Birjand, Iran |
| XBL | Buno Bedelle, Ethiopia |
| XBN | Benigni, Papua New Guinea |
| XBO | Bolsa, Burkina Faso |
| XBP | Bridgeport Municipal Airport, Bridgeport, Texas USA (formerly 1F9) |
| XBR | Brockville Aerodrome, Brockville, Ontario, Canada |
| XBW | Killineq, Ontario, Canada |
| XCD | Chalon - Champforgeuil Airport, Chalon-sur-Saone, France |
| XCH | Christmas Island, Australia |
| XCM | Chatham, Ontario, Canada |