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.