CREATE TABLE table_name_54 (on_air_id VARCHAR, band VARCHAR, callsign VARCHAR)

What is the On-air ID of FM broadcaster 4nsa?
SELECT on_air_id FROM table_name_54 WHERE band = "fm" AND callsign = "4nsa"
SELECT "on_air_id" FROM "table_name_54" WHERE "4nsa" = "callsign" AND "band" = "fm"