Please see the FAA article Ground-Based Navigation - Instrument Landing System (ILS)Ĭhoose the only correct statement about the localizer beam system used by aircraft to find the centerline of a runway during an Instrument Landing System (ILS) approach to an airport. See Wikipedia's article Instrument landing system. The horizontal guidance is provided by ground transmitters of 90 Hz and 150 Hz signals, so that the airplane stays within 10° of the centerline, and must correct if within 35° of the centerline on either side.įor vertical orientation, the same ground system of is simply turned sideways, providing upper 90 Hz and lower 150 Hz signals (Glideslope Signal), so that the airplane stays within the 3° angle.įor more information well-illustrated, please see Boldmethod site, for the article How An ILS Works. 'ILS uses two directional radio signals, the localizer (108 to 112 MHz frequency), which provides horizontal guidance, and the glideslope (329.15 to 335 MHz frequency) for vertical.' The Instrument Landing System (ILS), guides airplanes both horizontally and vertically.įrom Wikipedia's article Instrument landing system If you look closely at the bump on the right, that’s a GPS antenna. VOR antenna on the tail pointing backward. Here’s a picture of the most common arrangement.

Marker beacon, DME, and transponder antennas are on the bottom. The question asks for the frequency RANGE. In general, VOR, ELT, and GPS antennas are on the top of the plane. What is the frequency range of the localizer beam system used by aircraft to find the centerline of a runway during an Instrument Landing System (ILS) approach to an airport?

Localizer antenna location on aircraft