Flight lieutenant (Flt Lt in the RAF and IAF; FLTLT in the RAAF and RNZAF; formerly sometimes F/L in all services) is a junior commissioned air force rank which originated in the Royal Naval Air Service and continues to be used in the Royal Air Force and many other countries, especially in the Commonwealth. It is also sometimes used as the English translation of an equivalent rank in non-English-speaking countries, especially those which have an air force-specific rank structure.