Skip to page content

USA Banner

Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

United States Department of Transportation United States Department of Transportation

AC 20-199 - Installation of an Airborne Low-Range Radio Altimeter System

Document Information

Number
20-199
Title
Installation of an Airborne Low-Range Radio Altimeter System
Status
Active
Date issued
2026-07-24
Office of Primary Responsibility
AIR-626, Human Machine Interface Section
Description

This advisory circular (AC) provides guidance for the installation design approval of a radio altimeter (RA) system that is intended for showing compliance with the requirements of title 14, Code of Federal Regulations (14 CFR) 91.220(b). An RA system consists of an RA transceiver, RA antenna(s), coaxial cabling, and display(s) or indicator(s). This AC provides guidance for all components of the RA system, as well as for the use of the existing RA antenna(s) and display(s) or indicator(s). This AC includes guidance for system design (chapter 2 of this AC) and testing (chapter 3 of this AC) to assure proper functioning of the installed RA system, including external radio frequency interference (RFI) tolerance, as well as proper functioning of integrated avionics and flight control systems that utilize the RA. When the RA system is properly installed in an aircraft, in accordance with applicable installation and operational approval guidance and regulations, it is expected that all aircraft-level functional and operational performance criteria will be met.

Content