Instrument Landing Systems (ILS)


Systems Interface is second to none in its delivery of turnkey Instrument Landing Systems.

An Instrument Landing System (ILS system) is a ground-based radio navigation system giving pilots lateral and vertical guidance towards the runway when visual contact with the runway cannot be established.

These pieces of equipment are crucial for airports as they increase the reliability of every landing, reduce the decision altitude (altitude at which the pilot either commits to the landing procedure or diverts) and ultimately ensure that the pilot can understand the runway no matter the conditions.

How ILS Operates

ILS works by beaming two radio transmissions of different frequencies up from the landing runway, one of 90 Hz and one of 150 Hz. A radio beacon called a localiser is normally built at the end of the runway with multiple pairs of directional antennas.

Localisers are responsible for the horizontal guidance of the aircraft. On the aircraft, an ILS receiver interprets the information and reports which side the aeroplane is situated to allow the pilot to adjust accordingly. When both signals are overlapping, the aeroplane is flying perfectly down the centre of the course to the runway.

A glideslope antenna provides vertical guidance and operates the same as a localiser which is turned on its side. It also uses 90 Hz and 150 Hz frequencies which are interpreted by the ILS receiver on an aircraft.

Objects below 5,000 feet above ground level have the potential to reflect glideslope signals, which can create false glideslopes. These are often at 9- or 12-degree angles and pilots are taught to approach the glideslope from below to prevent their equipment from reading a false glideslope. In practice, pilots are unlikely to follow a false glideslope due to the extremely steep descent angle.

A marker beacon is a type of radio beacon used in conjunction with an ILS system and provides pilots with a way of establishing their position. This system provides pilots with three different position points which are the outer marker, the middle marker, and the inner marker.

A third antenna can also be installed which is the DME (Distance Measuring Equipment) giving a slant range towards the runway. However, the aircraft must have a DME receiver and be tuned to the correct DME frequency. Some instrument landing systems come with a built-in DME function, shown on an ILS chart for the runway as the letter D before the identifier code.

ILS Systems with Systems Interface

We have installed multiple ILS aviation systems at Military and Civil airports worldwide from CAT-I to full ICAO CAT-III systems. As with all products we provide full turnkey delivery, from civil works through to flight calibration.

Airports can benefit from our comprehensive approach to aerodrome safeguarding, instrument approach design, specifications, and system design. All supported, where needed, by sophisticated computer modelling techniques for selecting navaid sites and protection of ILS critical areas.

Systems Interface has developed an excellent relationship with the world's leading Navaid manufacturers, including:

  • Indra Navia AS (formerly NORMARC)
  • Selex
  • Thales
  • Moog

Allowing your project to benefit from the latest technological advancements and the highest quality ILS equipment.

To find out how we can supply, install, and commission your new ILS system or upgrade your existing system please fill out our enquiry form online or call our team on +44 (0)1483 267 066.

ISO Systems Interface is a fully
ISO 9001 : 2015 accredited organisation services solar-powered-airfield-lighting-products/

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