(Revised) MASPS for AMS(R)S Data Links

AMCP/WGC-WP/18

AERONAUTICAL MOBILE COMMUNICATIONS PANEL

Working Group C

THIRD MEETING

Anchorage, Alaska

15-19 October 2001

Agenda Item 2:Overview of Recent Developments

MASPS for AMS(R)S Data Links

Presented by Brent Phillips

(Prepared by R. A. Pickens)

AMCP/WGC-WP/18

1Introduction

RTCA Special Committee 165 (SC-165) on the Aeronautical Mobile Satellite Service (AMSS) has produced several documents relevant to AMS(R)S:

For several years, with the participation of Inmarsat and several potential AMS(R)S providers, the SC-165 has been developing a Minimum Aviation System Performance Standards (MASPS) document. Also, changes to update the two MOPS are in their final approval process.

2Completion of MASPS

On 12 October 2001, the RCA Program Management Committee approved for publication RTCA DO-270, Minimum Aviation System Performance Standards (MASPS) for the Aeronautical Mobile-Satellite (R) Service (AMS(R)S) As Used in Aeronautical Data Links. The MASPS contains standards for communications utilizing aeronautical mobile satellite systems for the air-ground communications subnetwork in an Aeronautical Telecommunications Network (ATN) environment. The FANS 1/A data link environment is also addressed.

The MASPS defines the general requirements of an AMS(R)S subnetwork, specific requirements for its interfaces, and specific minimum Installed Communications Performance (ICP) requirements when viewed as an air/ground subnetwork of an end-to-end data network. The ICP requirements include delay, integrity, availability and continuity of service parameters for the declared airspace coverage volume(s).

The AMS(R)S MASPS is intended to be independent of the wide variety of system architectures that may be capable of providing AMS(R)S, and was written under the assumption that a system can be characterized as conforming either to the ICAO "Chapter 4 SARPs" or to a set of requirements established for Next-Generation Satellite System (NGSS). The latter set is consistent with those of the "Draft NGSS SARPs" developed by the AMC Panel, and recognizes that NGSS could be implemented with geostationary-orbit (GSO) satellites and/or a variety of alternative constellation architectures including low-Earth-orbit (LEO) and medium-Earth-orbit (MEO) satellites. Where necessary, distinctions are made for the respective requirements for "Chapter 4" or NGSS systems.

The MASPS anticipates that a system may seek to qualify for either the minimum requirements or for a set of characteristics that exceeds the minimum requirements. The technical details of an individual system are required to be set out in a system-specific attachment written in accordance with pro forma tables and methodologies, and to be supported by verification procedures which may be satisfied by analysis, simulation and/or measurement. Specific methodologies for each approach are provided in either the document's body or normative appendices. The pro forma's and methodologies assure that the performance parameters and other characteristics are declared in standardized terms and dimensions; that account is taken of important influencing factors; and that verification procedures result in characterizations that are comparable among individual systems.

The preceding attributes will be important in the future application of the system-specific data to formulations of the Required Communications Performance (RCP) concept. The AMS(R)S MASPS performance parameters, as the characteristics of the air/ground communications element of an end-to-end data communication system, are suitable for use as the ICP factors for operational approval purposes, and are consistent with RTCA DO-264[1] for developing Operational Performance Assessments based on Required Communications Technical Performance (RCTP -- RCP with the human element removed).

The "system-specific attachments" are foreseen to be attachments to an application for approval for use in a specific operating environment. A system-specific attachment will not require RTCA approval or publication.

3Recommendation

The meeting is invited to note the existence of the AMS(R)S MASPS document, RTCA DO-270.

1

[1]DO-264, Guidelines for Approval of the Provision and Use of Air Traffic Services Supported by Data Communications. Appendix F of this document provides guidance on the development of an Operational Performance Assessment for a CNS/ATM component of any air traffic service supported by data communication.