AS9120B, ISO 9001:2015, and FAA AC 0056B ACCREDITED

What Are Radio Altimeters and Their Advantages?

When a pilot is operating an aircraft, there are various flight conditions that they must keep an eye on for safety and efficiency. One of the most important values to know during flight is one's altitude, that of which is the distance of the aircraft in relation to the ground below it. There are various ways in which altitude may be measured, one common way being the use of an aviation radio altimeter, or aircraft radar altimeter. With a radio altimeter, the distance between the aircraft and the terrain below can be determined with ease, allowing a pilot to conduct a safer landing in low-visibility conditions. In this blog, we will discuss the functionality of a radio altimeter and its design, allowing you to better understand how such devices are used.

Radio altimeter assemblies always feature a transceiver and directional antenna, and they are situated in such a way that carrier waves at 4.3 GHz are broadcasted from the aircraft toward the ground below. The wave is modulated at 50 MHz, and once it collides with a ground surface, it will bounce back toward the aircraft and be received by a second antenna. Once the return signal is received, it is then processed by the transceiver which utilizes the time it took for the signal to travel and the frequency modulation of the signal to determine the height above the terrain, that of which is known as the above ground level (AGL) value.

While most modern aircraft now rely on robust electronic altimeters that rely on pressure measurements for altitude, the aircraft radar altimeter is actually more accurate and responsive when the pilot requires AGL values while flying at low altitudes. Generally, the transceiver and indicator will be remote from one another, and such instruments may be paired with a multifunctional or glass cockpit display for the means of displaying decision height awareness as a digital number on a screen. For large aircraft where impacts are a major concern, the radio altimeter may even have its information incorporated into the ground proximity warning system (GPWS), ensuring that crew members are alerted if the aircraft ever enters a hazardous proximity range with the terrain below it.

As an aviation radio altimeter is primarily used for detecting terrain for the means of collision avoidance, it is generally only used while the aircraft is close to the ground. However, once the aircraft surpasses the 2500ft above ground level mark, radio altimeter height readings will cease. Nevertheless, their use is extremely important and beneficial during certain flight stages due to the safety of having such values and the accuracy of readings. If you are ever in the market for high quality radio altimeter parts or other aircraft instrumentation that you can steadily rely on, look no further than Stacked NSN.

Stacked NSN is a leading distributor for aviation radio altimeter parts and accessories, providing customers access to top-quality items offered with competitive pricing and rapid lead times. Explore our expansive inventory of over 2 billion items as you see fit, and our team is always ready to assist customers through the purchasing process however necessary. With our unwavering dedication to upholding rigorous quality control measures and export compliance standards, we proudly operate with AS9120B, ISO 9001:2015, and FAA AC 00-56B accreditation. Furthermore, we are the only independent distributor with a strict NO CHINA SOURCING pledge, meaning that all parts ship out alongside their qualifying certifications and manufacturing trace documentation, as applicable. If you are ready to begin, give our team a call or email at your earliest convenience and see how we can serve as your sourcing partner.


June 25, 2024


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