scope:

SCOPE AND INTRODUCTION

In the general sense, C2 describes a broad array of systems, procedures and operations that connect a pilot with control surfaces or other actuation that cause the aircraft to maneuver per his intended trajectory. The MOPS being developed under current TOR will characterize minimum performance standards for one key element of that broader chain - the airborne data link radio component.

Avionics System Certification Background and the Role of RTCA

A Technical Standard Order (TSO) from the FAA is a minimum performance standard for specified materials, parts, and appliances used on civil aircraft. When authorized to manufacture a material, part, or appliance to a TSO standard, this is referred to as TSO authorization. Receiving a TSO authorization is both design and production approval. Receiving a TSO Authorization is not an approval to install and use the article in the aircraft. It means that the article meets the specific TSO and the applicant is authorized to manufacture it.

RTCA has been formally designated to provide recommendations to the FAA under the Federal Advisory Committee Act. RTCA recommendations are generated by an industry consensus process through the work of Special Committees. Output of these committees comes in a variety of document types. Two of these document types are frequently referred to by the FAA in TSOs and Advisory Circulars (ACs) and, thereby, provide a partial basis for the certification of equipment. These two document types are:

• Minimum Aviation System Performance Standards (MASPS) - MASPS specify characteristics that are useful to designers, installers, manufacturers, service providers and users of systems intended for operational use within a defined airspace. Where the systems are global in nature, international applications are taken into consideration. MASPS describe the system (subsystems / functions) and provide information needed to understand the rationale for system characteristics, operational goals, requirements and typical applications. Definitions and assumptions essential to proper understanding of MASPS are provided as well as minimum system test procedures to verify system performance compliance (e.g., end-to-end performance verification).

Compliance with RTCA MASPS is recommended as one means of assuring that the system and each subsystem will perform its intended function(s) satisfactorily under conditions normally encountered in routine aeronautical operations for the environments intended. MASPS may be implemented in part or in total.

• Minimum Operation Performance Standards (MOPS) - MOPS provide standards for specific equipment(s) useful to designers, manufacturers, installers and users of the equipment. The word "equipment" used in MOPS includes all components and units necessary for the system to properly perform its intended function(s). MOPS provide the information needed to understand the rationale for equipment characteristics and requirements stated, describe typical equipment applications and operational goals, and establish the basis for required performance under the standard. Definitions and assumptions essential to proper understanding are provided as well as installed equipment tests and operational performance characteristics for equipment installations.

Compliance with RTCA MOPS is recommended as one means of assuring the equipment will perform its intended function(s) satisfactorily under all conditions normally encountered in routine aeronautical operations. MOPS may be implemented by one or more regulatory documents and/or advisory documents and may be implemented in part or in total.

As described above, a MASPS is developed to provide functions, operations, intended use, etc. for a specific aviation system capability. In general, MASPS are independent of specific technology and implementation details. In fact, it is often the case that multiple technology-specific designs are brought forward which each complies with the MASPS, but with differing design instantiations to meet the needs of different applications or operational intents.

In contrast, MOPS are focused to provide certification performance standards for specific pieces of equipment using specified technologies and designs. These requirements are organized into three areas: 1) general requirements, 2) equipment performance (standard conditions) and 3) environmental requirements. The level of detail of each of these sections varies with the needs of the specific equipment. In some cases the MOPS can be quite prescriptive, as with the Traffic Collision and Avoidance System (TCAS) where the specific algorithms to be used are specified.

Typically when a new capability is being developed, as MASPS is first written to provide that "technology agnostic" set of characteristics that will meet the operational intent of the capability under development. Later, one or more MOPS will be developed to provide specific solutions to sufficient detail to permit manufacturers to fabricate designs and bring them forward under the TSO approval process, providing authorization to manufacture the part. Applicants for aircraft type certification can then include these TSO approved parts as a portion of their certification basis. Use of TSO parts expedites the certification process as a significant body of verification and validation has already been accepted by the FAA for parts manufactured in compliance with the TSO.

SC-228 Tasking and Approach

The SC-228 TOR calls out a C2 MOPS as the initial required deliverable from this Working Group. Prior work by Special Committee 203 (Unmanned Aircraft Systems) generated three foundational documents which begin the typical requirements chain leading to MOPS:

• DO-304 "Guidance Material and Considerations for Unmanned Aircraft Systems", March, 2007.

• DO-320 "Operational Services and Environmental Description for Unmanned Aircraft Systems", June 2010

• DO-344 "Operational and Functional Requirements and Safety Objectives for Unmanned Aircraft Systems", June 2013

Typically these documents would be followed by one or more MASPS prior to commencing work on MOPS. SC-203 was sunset by the RTCA Program Management Committee prior to completion of its original TOR, which included UAS MASPS, DAA MASPS and C2 MASPS.

Though the specific tasking of SC-228 is to proceed directly to MOPS, it is clear there is a need to generate a body of "MASPS-like" material to fill in some key gaps, in conjunction with the MOPS proper. Lacking a broader set of system level bounding and performance requirements it will be critical for SC-228 to carefully capture assumed requirements and their implications for the broader aviation system integration and certification framework. Typically a TSO based on MOPS is one means, but not the only means, of compliance with a given operational need. Selection of specific performance and/or design choices in these MOPS could potentially have the unintended consequence of limiting or precluding other approaches as this system uses a key shared resource in the electromagnetic spectrum.

ASSERTION:

Any "MASPS-like" material included in the MOPS should be cleanly segregated from the MOPS proper (i.e., normative material specifying equipment and technology unique design information).

Keeping the aviation system level (technology agnostic) information segregated will help clearly delineate the assumed requirements on ANY technology / design brought forward in the future to ensure compatibility with the system specified in this MOPS. Within this white paper, any MASPS-like candidate information will be characterized as such.

The MASPS-like material that is included will only be of the scope required to achieve two basic objectives:

1. Support a UAS Control and Non-Payload Communications (CNPC) radio and UAS spectrum assignment and reuse planning, and

2. Ensure compatibility of UAS communications with other existing aeronautical systems.

As such, the MASPS-like material provides for compatibility of the waveform components developed in the CNPC MOPS with other technology-specific instantiations that may be characterized in the future. The CNPC MOPS proper will go beyond electromagnetic compatibility and will also provide standards for a specific initial CNPC waveform which addresses the scope of the RTCA SC-228 Terms of Reference (TOR).