How Does an Aircraft Instrument Landing System Work?

By far, aviation serves as one of the safest ways to travel, and this is made possible through rigorous regulations and advanced technology. With a variety of robust systems, pilots are provided ample assistance and aid during various flight conditions, ensuring they always have the tools and resources at hand to efficiently and safely carry out an operation. For instance, the landing process can be complex, especially if weather phenomena detracts from overall visibility of the runway. As landing without visuals would be highly dangerous, pilots utilize what is known as the Instrument Landing System (ILS) to optimally touchdown at the end of a flight.

While the ILS can be considered a cockpit instrument, it also relies on airport technology that emits sets of radio waves for the means of determining directional and positional data. Based on various conditions, altitudes, and other factors, aircraft may take advantage of various systems that belong to different categories. Additionally, some pilots may also utilize alternative navigational aids provided by the airport in lieu of the ILS. Nevertheless, the ILS has been in use since the technology’s first adoption in 1929, making it likely that pilots will eventually have to utilize one if they have not already.

The Instrument Landing System is considered a type of precision landing aid, and it provides an aircraft with azimuth and descent signals that help the pilot correctly land the aircraft on a runway during low visibility weather conditions. Generally, the ILS is used when a clean visual approach is deterred by poor weather, low light during night, or other various adverse conditions. While the pilot is charged with deciding whether or not the ILS is required for a landing, they will still need to have permission from Air Traffic Control. Additionally, pilots may also conduct non-ILS approaches with the aid of ILS data, generally relying on the localizer and glideslope. While ILS landings may be conducted during optimal weather and light conditions, it is not typical as visual approaches provide more reaction time to address potential emergencies.

While there are various types of Instrument Landing Systems that one may take advantage of, all function with assistance from three ground facilities. The first ground facility is the localizer, and it serves to create a horizontal plane to provide a pilot with a display of the center runway line on their instrument. Meanwhile, the Glide Path ensures that a vertical plane is available to the pilot, allowing them to approach the runway at a right angle for an optimal touchdown. The final type of ground facility encompasses the various market beacons that line up along the approach line, allowing the pilot to better align themselves as they approach the landing.

As discussed before, the airport will provide the aircraft with two radio signals, and these are the localizer and glideslope signal. The localizer is used for lateral guidance, and such signals are provided by a transmitter that is situated at the end of a runway. Meanwhile, the glideslope ensures vertical guidance, and such signals are sent by transmitters placed on the sides of the runway. Both radio signals are received by the aircraft with onboard equipment, and such technology will rapidly interpret signals to determine the live position of the aircraft.

In general, there are three categories of ILSs, each of which differ in their capabilities. Category 1 ILS equipment is best for small, general aviation aircraft, and pilots should fly visually at about 200 feet above the runway with this system. Category 2 ILS equipment is somewhat different, allowing pilots to fly visually between an altitude of 100 and 200 feet. The final type is the Category 3 ILS, and they are for flying below an altitude of 100 feet for when automatic landings are conducted during poor visibility conditions. The Category 3 ILS can further be divided into three sub-categories, those of which differ in their capabilities and limitations. While ILS equipment is fairly popular, it is not always present in every aircraft. As such, if you are looking to fit your aircraft with an ILS system, or simply need ILS parts for MRO needs, let the experts at NSN Purchasing help you fulfill all your operational requirements with highly competitive pricing and rapid lead times.

NSN Purchasing is a premier distribution platform for aviation parts of all types, meaning that we are your source for landing gear components, instrument landing indicator products, engine parts, and so much more. Take the time to explore our massive set of offerings as you see fit, and you may always take advantage of our online RFQ service for the means of requesting quotes for your comparisons. Within 15 minutes of our team receiving and reviewing your request, you will receive a customized solution that caters to your needs. Experience why customers continuously rely on NSN Purchasing for all their operational requirements when you kickstart the procurement process with us today! 


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