1 definition by 737 California Air
An instrument approach system used in aviation. Short for Localiser and can also be used for the LNAV. Some planes may have APP which is a combination of the LOC function and the G/S (Glide Slope). APP is short for Approach. The LOC or ILS arms the G/S to the runway. Each runway at an airport typically has different ILS numbers (Set in your NAV 1 or 2 radio frequency), but some major airports have it in both directions such as KLAX. For missed approaches, use your BC (Back Course).
by 737 California Air May 30, 2011