Instrument Landing Systems Instruments and Avionics Blake Crosby

What Is An Instrument Landing System? The ILS is designed to provide an aircraft with a precision final approach with horizontal and vertical guidance to the runway. The ground equipment consists of a localizer, a glide path transmitter and an NDB along the approach path. A DME fix may replace the NDB. 9/17/2018 Instrument Landing Systems

Instrument Landing Systems Why? Scheduled service would be impossible without a way to land in poor weather. Provide a standard way to land and take off from any airport in the world. Additional safety and situational awareness. 9/17/2018 Instrument Landing Systems

Instrument Landing Systems History Tests of the first ILS began in 1929 The first scheduled passenger airliner to land using ILS was in 1938. A Pennsylvania-Central Airlines Boeing 247-D from Washington to Pittsburgh. Unlike the original system developed by the CAA, the US Army standard was not prone to static and had straighter glideslopes and localizer beams. In 1949, ICAO adapted an ILS standard developed by the US Army as a standard system for all of its member countries. 9/17/2018 Instrument Landing Systems

Instrument Landing Systems 9/17/2018 Instrument Landing Systems

Instrument Landing Systems 9/17/2018 Instrument Landing Systems

Instrument Landing Systems 9/17/2018 Instrument Landing Systems

Instrument Landing Systems How It Works Glideslope Provides vertical navigation Localizer Provides horizontal navigation NDB/ADF or DME Provides distance from runway 9/17/2018 Instrument Landing Systems

Instrument Landing Systems How It Works Localizer Antenna is located on the opposite end of the runway. Both the localizer and and glideslope emit two “tones” one at 90 hertz and the other at 150. Glideslope Antenna is located on one side of the runway at approx. touch down point. 9/17/2018 Instrument Landing Systems

Glideslope Antenna Array 9/17/2018 Instrument Landing Systems

Localizer Antenna Array 9/17/2018 Instrument Landing Systems

Instrument Landing Systems NDB Antenna 9/17/2018 Instrument Landing Systems

Course Deviation Indicator Signal Integrity Flag Indicates if instrument is unreliable “Dots” Each “dot” on the instrument represents 2° of deviation Localizer Deviation from runway centre line Glideslope Deviation from optimal glide path 9/17/2018 Instrument Landing Systems

Limitations of current ILS Localizer is sensitive to obstructions like buildings and terrain. Glideslope errors can occur if terrain is sloping or is uneven infront of the antenna. Since antennas point in a single direction, only “straight” approaches are available. Can be costly. 9/17/2018 Instrument Landing Systems

Instrument Landing Systems Other types of ILS Microwave Landing System Curved approaches are possible Less interference and more accurate than traditional ILS Used mostly in Europe Being replaced by GPS approaches Transponder Landing System Easy and quick to deploy in remote locations Only one airplane can use the system at a time. No additional equipment needed on aircraft. Similar system used by the military. 9/17/2018 Instrument Landing Systems

Instrument Landing Systems Videos http://www.youtube.com/watch?v=M3wnl1Ut--o http://www.youtube.com/watch?v=ZnEtr6Ei1sc 9/17/2018 Instrument Landing Systems