Who and where can access the list of ICAO24 addresses?

Question

Who and where can access the list of ICAO24 addresses?

Answer 1

The blocks of ICAO addresses assigned to each state can be found in this document. How each state assigns its block to individual aircraft is up to the state, and there is no authoritative source where you can look up any worldwide ICAO address.

The United States, for example, uses a simple map of tail number to ICAO address. They are assigned all addresses from A00000 to AFFFFF. A00001 is given to N1, A00002 to N1A, A00003 to N1AA, and so on in order up to ADF7C7 for N99999.

It may be puzzling that no such map exists for aircraft worldwide. But from an operational standpoint it doesn't matter which address is mapped to which aircraft. The only thing that matters is that no two aircraft share an address.