Avionics

An emergency locator transmitter (ELT) is an independent battery-powered transmitter activated by excessive G-forces experienced during a crash. It transmits a digital signal every 50 seconds on a frequency of 406.025 MHz at 5 watts for at least 24 hours. The signal is received anywhere in the world by satellites in the Cospas-Sarsat satellite system. … Read more

There are three common types of weather detection systems used in an aircraft flight deck that are often referred to as weather radar: On-board weather radar systems can be found in aircraft of all sizes. They function similarly to ATC primary radar except the radio waves reflect from precipitation instead of aircraft. Dense precipitation creates … Read more

Area Navigation (RNAV) Area navigation (RNAV) is a general term used to describe the navigation from point A to point B without direct overflight of navigational aids, such as VOR stations or ADF non-directional beacons. It includes VORTAC- and VOR/DME-based systems, as well as systems of RNAV based around LORAN, GPS, INS, and the FMS … Read more

Radio Magnetic Indicator (RMI) To save space in the instrument panel and to consolidate related information into one easy-to-use location, the radio magnetic indicator (RMI) has been developed. It is widely used. The RMI combines indications from a magnetic compass, VOR, and ADF into one instrument. [Figure 1] The azimuth card of the RMI is … Read more

A radar beacon transponder, or simply, a transponder, provides positive identification and location of an aircraft on the radar screens of ATC. For each aircraft equipped with an altitude encoder, the transponder also provides the pressure altitude of the aircraft to be displayed adjacent to the on-screen blip that represents the aircraft. [Figure 1] Radar … Read more

The ever increasing volume of air traffic has caused a corresponding increase in concern over collision avoidance. Ground-based radar, traffic control, and visual scanning are no longer adequate in today’s increasingly crowded skies. Onboard collision avoidance equipment, long a staple in larger aircraft, is now common in general aviation aircraft. New applications of electronic technology … Read more

An automatic direction finder (ADF) operates using a ground signal transmitted from a NDB. Early radio direction finders (RDF) used the same principle. A vertically polarized antenna was used to transmit LF frequency radio waves in the 190 kHz to 535 kHz range. A receiver on the aircraft was tuned to the transmission frequency of … Read more

One of the oldest and most useful navigational aids is the very high frequency omni-directional range (VOR) navigation system. The four main components of a typical system are: a receiver, a visual indicator, a frequency selector (controller or control panel), and antennas. The system was developed after World War II and is still in use … Read more

An ILS is used to land an aircraft when visibility is poor. This radio navigation system guides the aircraft down a slope to the touchdown area on the runway. Multiple radio transmissions are used that enable an exact approach to landing with an ILS. A localizer is one of the radio transmissions. It is used … Read more

An inertial navigation system (INS) is used on some large aircraft for long-range navigation. This may also be identified as an inertial reference system (IRS), although the IRS designation is generally reserved for more modern systems. An INS/IRS is a self-contained system that does not require input radio signals from a ground navigation facility or … Read more