CREATE TABLE table_203_688 (id NUMBER, "category" CLOB, "speed\ ( km/h ) " NUMBER, "speed\ ( mph ) " NUMBER, "vehicle" CLOB, "pilot" CLOB, "date" CLOB)

who was the pilot for the north american x-15 ?
SELECT "pilot" FROM table_203_688 WHERE "vehicle" = 'north american x-15'
SELECT "pilot" FROM "table_203_688" WHERE "vehicle" = 'north american x-15'