Definition
A non-precision instrument approach that uses the localizer component of an Instrument Landing System (ILS) to provide lateral guidance to a runway, but does not provide electronic vertical (glideslope) guidance. The pilot follows the localizer course to align with the runway centerline and descends in steps to published minimum altitudes until reaching the Minimum Descent Altitude (MDA), from which the runway must be seen to continue to land.
Plain English
An approach that gives the pilot a radio signal showing whether they are left or right of the runway centerline, but does not show whether they are too high or too low. The pilot handles the descent themselves using the published altitudes on the chart.
Context Anchor
Seen on instrument approach charts and during instrument flying when an ILS localizer is available but the approach is flown without glidepath guidance.
Derivation
Localizer' comes from 'localize' — to fix or determine a position. The localizer signal localizes the aircraft laterally with respect to the runway centerline.
Why Pilots Care
Pilots must know when a localizer approach is available so they can plan for higher minimum altitudes and the correct missed approach procedure if the runway is not in sight.
Grounding Statement
On a localizer approach, the needle can keep you centered left and right, but it does not tell you when to descend.
Intuition Check
Do not assume a localizer approach is the same as a full ILS approach. A localizer approach uses the localizer for left-right guidance only; descent comes from the published procedure.
Example Sentence 1
With the glideslope out of service, the crew briefed the localizer approach to runway 27 and noted the higher MDA on the chart.
Example Sentence 2
During the localizer approach the crew descended to the published minimum descent altitude while tracking the course needle.