RTCA, Inc.

1140 Connecticut Avenue, NW, Suite 1020

Washington, DC 20036-4001, USA

**Minimum Aviation System Performance**

**Standards (MASPS)**

**Drafting Guide**

  ----------------------------------- -----------------------------------
  Updated: Month day, year            Prepared by: RTCA, Inc.

  RTCA/DO-???                         © 2000, RTCA, Inc.
  ----------------------------------- -----------------------------------

Copies of this document may be obtained from

RTCA, Inc.

1140 Connecticut Avenue, NW, Suite 1020

Washington, DC 20036-4001, USA

Telephone: 202-833-9339

Facsimile: 202-833-9434

Internet: www.rtca.org

Please call RTCA for price and ordering information

FOREWORD

This document was prepared by RTCA for use as a guide in the production
of Minimum Aviation System Performance Standards (MASPS). It was
approved by the RTCA Program Management Committee on MONTH XX, 2000.

RTCA, Incorporated is a not-for-profit corporation formed to advance the
art and science of aviation and aviation electronic systems for the
benefit of the public. The organization functions as a Federal Advisory
Committee and develops consensus-based recommendations on contemporary
aviation issues. RTCA's objectives include, but are not limited to:

-   Coalescing aviation system user and provider technical requirements
    in a manner that helps government and industry meet their mutual
    objectives and responsibilities;

-   Analyzing and recommending solutions to the system technical issues
    that aviation faces as it continues to pursue increased safety,
    system capacity and efficiency;

-   Developing consensus on the application of pertinent technology to
    fulfill user and provider requirements, including development of
    Minimum Operational Performance Standards (MOPS) for electronic
    systems and equipment that support aviation; and

-   Assisting in developing the appropriate technical material upon
    which positions for the International Civil Aviation Organization
    (ICAO) and the International Telecommunication Union (ITU) and other
    appropriate international organizations can be based.

The recommendations of RTCA are often used as the basis for government
and private sector decisions as well as the foundation for many Federal
Aviation Administration Technical Standard Orders (TSO).

Since RTCA is not an official agency of the United States Government,
its recommendations may not be regarded as statements of official
government policy unless so enunciated by the United States Government
organization or agency having statutory jurisdiction over any matters to
which the recommendations relate.

This MASPS Drafting Guide presents the basic Minimum Operational
Performance Standards (MOPS) format augmented with drafting guidance.
This includes guidance on total system performance and related subsystem
performance necessary for complete system operation. Test requirements
for performance verification should be included for each
subsystem/element in addition to the system.

Evaluation of new systems, in general where system performance is not
clear or where numerous alternatives may exist, should be documented as
reports on the system using a general format (e.g., introduction, system
description, assumptions/terms, operation capabilities, conclusions and
recommendations) instead of a MASPS or MOPS.

This Page Intentionally Left Blank

TABLE OF CONTENTS

[1 PURPOSE AND SCOPE 1](#purpose-and-scope)

[1.1 Introduction 1](#introduction)

[1.2 System Overview 2](#system-overview)

[1.3 Operational Application(s) 2](#operational-applications)

[1.4 Operational Goals 2](#operational-goals)

[1.5 Assumptions 2](#assumptions)

[1.6 Verification Procedures 3](#verification-procedures)

[1.7 Definition of Terms 3](#definition-of-terms)

[2 System Performance Requirements 5](#system-performance-requirements)

[2.1 General Requirements 5](#general-requirements)

[2.2 System Performance -- Standard Operational Conditions
5](#system-performance-standard-operational-conditions)

[3 SYSTEM/FUNCTION PERFORMANCE REQUIREMENTS
7](#systemfunction-performance-requirements)

[3.1 General Requirements 7](#general-requirements-1)

[3.2 Subsystem Performance -- Standard Operational Conditions
7](#subsystem-performance-standard-operational-conditions)

[4 PROCEDURES FOR PERFORMANCE REQUIREMENT VERIFICATION
9](#procedures-for-performance-requirement-verification)

This Page Intentionally Left Blank

# PURPOSE AND SCOPE

## Introduction

This document contains Minimum Aviation System Performance Standards for
(NAME OF THE SYSTEM.[^1]) These standards specify system characteristics
that should be useful to designers, manufacturers, installers, service
providers and users for systems intended for operational use with the
United States National Airspace System (NAS). Where systems are global
in nature, the system may have international applications which are
taken into consideration.

Compliance with these standards is recommended as one means of assuring
that the system and each subsystem will perform its intended function(s)
satisfactorily under all conditions normally encountered in routine
aeronautical operations for the environments intended. The MASPS may be
implemented by one or more regulatory documents and/or advisory
documents (e.g., certifications, authorizations, approvals,
commissioning, advisory circulars, notices, etc.) and may be implemented
in part or in total. Any regulatory application of this document is the
sole responsibility of appropriate governmental agencies.

[Section 1]{.underline} of this document describes the (NAME OF THE
SYSTEM) and provides information needed to understand the rationale for
system characteristics and requirements that are stated by (NAME OF THE
SYSTEM) comprising the (NAME OF THE SUBSYSTEMS/FUNCTIONS) in the
remaining sections. It describes typical applications and operation
goals, as envisioned by the members of Special Committee **TBD**, and
establishes the basis for the standards stated in Sections 2 through 4.
Definitions and assumptions essential to proper understanding of this
document are also provided in this section.

[Section 2]{.underline} describes Minimum System Performance
requirements for the system. (E.G., SECTION 2 MAY INCLUDE OVERALL
END-TO-END PERFORMANCE OF COMMUNICATIONS NETWORKS OR APPLICATIONS USING
THE COMMUNICATIONS NETWORKS). ENHANCED SYSTEM PERFORMANCE REQUIREMENTS
MAY BE INCLUDED IN A NON-NORMATIVE APPENDIX FOR GUIDANCE.

[Section 3]{.underline} contains the minimum performance standards for
each subsystem/function that is a required element of minimum system
performance in Section 2. These standards specify the required
performance under the standard environmental conditions described.

[Section 4]{.underline} describes the minimum system test procedures to
verify system performance compliance (e.g., end-to-end performance
verification) and that subsystem performance meets the minimum
performance requirements in Sections 2 and 3.

The word "subsystem" as used in this document includes all components
that make up a major independent, necessary and essential functional
part of the system so that the system can properly perform its intended
function(s). If the system, including any subsystem, includes computer
software, the guidelines contained in RTCA Document DO-178B, *Software
Consideration in Airborne Systems and Equipment Certification*, should
be considered even for non-airborne applications.

## System Overview

Describe the system, in general terms, to establish a basic
understanding of the system and subsystems, and how the subsystems
function in the system.

## Operational Application(s)

Describe typical system operational application(s).

## Operational Goals

Operational goals dictate the basic requirements that the system is
intended to satisfy. Wherever possible, the system requirements cited in
Section 2 should have their foundation established in this section, as
necessary, to answer the question as to [why]{.underline} the stated
requirements are necessary.

Define these goals, wherever possible, in operational terms. Items to be
considered may include the following:

a.  Accuracy

b.  Integrity

c.  Availability

d.  Continuity of Function

e.  Performance parameters (e.g., throughput, message delivery time,
    circuit setup time, etc.)

f.  Failure modes, warnings and flags

g.  Human Factor Considerations

h.  Operational modes

i.  Operational limitations

j.  Etc.

## Assumptions

Describe the assumptions made that have a bearing on stated
requirements. Where possible, include a statement regarding the
sensitivity of each requirement.

## Verification Procedures

The verification procedures specified in this document are intended to
be used as one means of demonstrating compliance with the performance
requirements. Although specific test procedures are cited, it is
recognized that other methods may be used. These alternate procedures
may be used if it can be demonstrated that they provide at least
equivalent information. System performance tests as they relate to
operational capability are the most important test. Subsystem tests are
useful as subsystems are added during system buildup and to ensure
continued subsystem performance as it relates to system performance.

## Definition of Terms

Define those terms used in this document that could have multiple
meanings or are not normally used. (Long lists may be placed in an
appendix.)

This Page Intentionally Left Blank

# System Performance Requirements

## General Requirements

General system requirements need not be tested in Section 4. If a
requirement needs to be tested, it is [not]{.underline} a general
requirement and should be included in Subsection 2.2.

## System Performance -- Standard Operational Conditions

USE SUBORDINATE PARAGRAPHS TO STATE REQUIREMENTS THAT THE OVERALL SYSTEM
SHALL MEET WHEN OPERATING IN THE INTENDED OPERATIONAL ENVIRONMENT. THE
FOLLOWING GUIDLINES ILLUSTRATE SOME OF THE MORE IMPORTANT ASPECTS THAT
THE COMMITTEE WOULD CONSDIER DURING PREPARATION OF SECTION 2.2.

a.  Requirements should be limited to those that are essential to the
    intended use(s) of the system. These requirements should be
    expressed in terms of minimum performance, e.g., the threshold of
    performance requirements and values that must be achieved in a
    prescribed operational environment. When stating these requirements,
    it is important that they be confined to performance rather than
    design specifications, thereby permitting maximum freedom of design
    choice.

b.  In general, use one paragraph to express a single requirement.

c.  Requirements should be expressed in measurable terms so that they
    can be verified by a test procedure in Section 4.

d.  Particular care must be taken to assure that the requirement
    statement is compatible with the test procedure in Section 4.

e.  Clearly identify points in the system where the performance
    requirement applies.

```{=html}
<!-- -->
```
F.  An example of end-to-end system performance for message delay is
    shown below in Table 2-1. Note that the system delay is the sum of
    each subsystem delay.

Table 2-1 Example of End-to-End System Performance for Message Delay

  -------------- ------------ ------------- --------------- -------------- ------------- ------------ -----------
  **Example of                                                                                        
  End-to-End                                                                                          
  System                                                                                              
  Performance                                                                                         
  for Message                                                                                         
  Delay**                                                                                             

                                                                                                      

  **Air Traffic  **Ground     **Ground User **Terrestrial   **Air/Ground   **Aircraft    **Aircraft   **Pilot**
  Controller**   Terminal**   Subsystem**   Subsystem**     Subsystem**    Subsystem**   Terminal**   

  **A**          **B**        **C**         **D**           **E**          **F**         **G**        **H**

                                                                                                      

  **Delay                                                                                             
  ~System~                                                                                            
  (D)~S~ = D +                                                                                        
  ~A~D + ~B~D +                                                                                       
  ~C~D + ~D~D +                                                                                       
  ~E~D + ~F~D +                                                                                       
  ~G~D + ~H~D**                                                                                       

                                                                                                      
  -------------- ------------ ------------- --------------- -------------- ------------- ------------ -----------

# SYSTEM/FUNCTION PERFORMANCE REQUIREMENTS

## General Requirements

GENERAL SUBSYSTEM REQUIREMENTS NEED NOT BE TESTED IN SECTION 4. IF A
REQUIREMENT NEEDS TO BE TESTED, IT IS [NOT]{.underline} A GENERAL
REQUIREMENT AND SHOULD BE INCLUDED IN SUBSECTION 3.2.

## Subsystem Performance -- Standard Operational Conditions

USE SIMILAR GUIDELINES AS CONTAINED IN SECTION 2.2 FOR SYSTEM
PERFORMANCE. INCLUDE ONLY THOSE SUBSYSTEM PERFORMANCE REQUIREMENTS
RELATED TO THE SYSTEM PERFORMANCE STATED IN SECTION 2. PERFORMANCE OF
EACH SUBSYSTEM/FUNCTION SHOULD ADD UP TO THE TOTAL SYSTEM PERFORMANCE.

This Page Intentionally Left Blank

# PROCEDURES FOR PERFORMANCE REQUIREMENT VERIFICATION

USE SUBORDINATE PARAGRAPHS TO DETAIL PROCEDURES ON HOW EACH REQUIREMENT
IS TO BE VERIFIED. EACH PROCEDURE SHOULD IDENTIFY RELATED REQUIREMENTS
IN SECTIONS 2 AND 3. THE PROCEDURE SHOULD CLEARLY IDENTIFY THE TEST
POINTS WHERE PERFORMANCE REQUIREMENTS ARE TO BE VERIFIED AND THE
SPECIFIC VALUES FOR PASSAGE. EACH PROCEDURE SHOULD BE DETAILED ENOUGH SO
THAT IT IS CLEAR WHAT PARAMETERS ARE BEING VERIFIED.

PERFORMANCE REQUIREMENTS MAY BE VERIFIED BY:

a.  PERFORMANCE MEASUREMENT -- (PREFERRED METHOD)

b.  MODELING AND SIMULATION

c.  ANALYSIS

This Page Intentionally Left Blank

[^1]: Capitalized text in this Guide provides guidance concerning
    details needed for the specific system and subsystem/function
    requirements described in the MASPS.