Description / Abstract: Introduction

This document contains Minimum Operational Performance Standards for Selective Calling (SELCAL) systems installed in all types of aircraft. These standards specify system characteristics that should be useful to designers, manufacturers, installers and users of the equipment.

Compliance with these standards is recommended as one means of assuring that the equipment will perform its intended function(s) satisfactorily under all conditions normally encountered in routine aeronautical operation. Any regulatory application of this document is the sole responsibility of appropriate governmental agencies.

Section 1 of this document provides information needed to understand the rationale for equipment characteristics and requirements stated in the remaining sections. It describes typical equipment operations and operation goals, as envisioned by the members of Special Committee SC-232, and establishes the basis for the standards stated in Sections 2 through 3. Definitions and assumptions essential to proper understanding of this document are also provided in this section.

Section 2 contains the Minimum Performance Standards for the equipment. These standards specify the required performance under standard environmental conditions. Also included are recommended bench test procedures necessary to demonstrate equipment compliance with the stated minimum requirements.

Section 3 describes the performance required of installed equipment. Tests for the installed equipment are included when performance cannot be adequately determined through bench testing. Section 4 describes the operational performance characteristics for equipment installations and defines conditions that will assure the equipment user that operations can be conducted safely and reliably in the expected operational environment.

This document considers an equipment configuration consisting of a SELCAL Unit and VHF and/or HF transceivers. Operational performance standards for functions or components that refer to equipment capabilities that exceed the stated minimum requirements are identified as optional features. The word “equipment” as used in this document includes all components and units necessary for the system to properly perform its intended function(s). For example, the “equipment” may include a standalone SELCAL decoder or an Audio System with integrated SELCAL functionality. Each design will include both SELCAL decoding and annunciating capabilities as well as a means of configuring the unique SELCAL code for the aircraft.

This MOPS applies to a specific defined function. The equipment may have additional features related to that function for which there are no specified minimum performance requirements. For example, many VHF radios have an active-standby frequency “flip-flop” feature for which there are no specified requirements or tests. Equipment may also have additional functions for which other MOPS or TSOs may be applicable or it may contain additional functions not defined by any MOPS or TSO, in which case non-TSO function guidance may be applicable.

If the equipment implementation includes a computer software package, the guidelines contained in RTCA Document No. DO-178C, (or the most current published revision) Software Consideration in Airborne Systems and Equipment Certification, should be considered.