Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_63 ( icao VARCHAR, callsign VARCHAR )

### Question ###
What is the ICAO for Air Busan?

### Accurate SQL ###

SELECT icao FROM table_name_63 WHERE callsign = "air busan"