2.1 While traditional voice communications continue to provide a principal element of aviation communications, other forms of communication, such as digital data transfer, are becoming increasingly prevalent in supporting navigation, surveillance and tactical operations. The ICAO Manual on Required Communication Performance highlights the need for communications to be assured in high density airspace using a mixture of traditional voice and data link communications. A number of communication systems are also mandatory for flight in specified civil airspace, particularly to satisfy performance based navigation.
2.2 For the majority of communication systems, compliance with the airworthiness design requirements prescribed in an Authority recognised Airworthiness Code provides assurance of the safe design and operation of these systems in Defence aircraft. However, many civil and military Airworthiness Codes do not prescribe design requirements for communication systems that support specific aircraft operations (eg Required Navigation Performance) or missions. Such requirements are generally defined in supporting guidance material that is only invoked when the aircraft operator seeks approval to conduct the applicable operations. Consequently, the Authority prescribes airworthiness design requirements for communication systems to supplement the Airworthiness Codes and provide a basis for verifying the acceptability of the associated communication systems for safe operations or to satisfy capability requirements for Defence aircraft.
2.3 This Chapter prescribes Authority supplementation to the aircraft communications systems elements of recognised civil and military Airworthiness Codes. Importantly, the airworthiness design requirements in this chapter are not suitable for application in isolation from an Airworthiness Code. The Authority’s requirements for the application of recognised Airworthiness Codes are defined in Section 1 of this manual.
2.4 Communications systems must meet the requirements prescribed for operations in specific classes of airspace, and to navigate in civil airspace and along specified civil routes. Prior to establishing the airworthiness design requirements that must be met for a Defence aircraft’s communication systems, the designer must confirm the global airspace and navigation environment in which the Defence aircraft will operate, and consequently establish the communications systems requirements necessary to achieve safe aircraft operations.
2.5 Design Requirement (Essential). The communication systems fitted to Defence aircraft must satisfy the minimum systems/equipment and functional requirements for proposed operations in civil airspace as prescribed by the administering NAA.
2.6 Design Requirement (Essential). The communication systems fitted to Defence aircraft must satisfy the minimum systems/equipment and functional requirements for proposed navigation in civil airspace as prescribed by the administering NAA.
2.7 When establishing the communication systems and equipment to be fitted to Defence aircraft, designers must ensure that the minimum systems required to support proposed operations in world-wide civil airspace (both for communication between aircraft and/or ATC and for navigation in civil airspace) are installed and satisfy the applicable design standards. In particular, civil airspace routes are increasingly adopting Performance Based Communications and Surveillance protocols, which require communications systems to meet prescribed performance criteria (ie data link capabilities and communication expiry times) to operate on those routes. Failure to ensure required communication systems are installed may result in loss of crew situational awareness or limitations on access to civil airspace.
2.8 Noting that inadequate communications capability may result in denial of access to civil airspace, and that Defence aircraft acquisition can be an extended activity, designers should ensure that communication systems functional requirements are identified both for current civil airspace operations and for future operations (3-5 years post introduction into service). This will ensure that Defence aircraft are capable of safely operating in civil airspace without restriction in the short to medium term.
2.9 Design Requirement (Essential). Defence aircraft that will operate in airspace that requires an 8.33 kHz channel separation must be fitted with VHF communications equipment that satisfies the requirements of:
ED-23C, Minimum Operational Performance Standards for Airborne VHF receiver-transmitter operating in the frequency range 117.975 – 137.00 MHz, or
TSO-C169a, VHF Radio Communications Transceiver Equipment Operating within Radio Frequency Range 117.975 to 137.000 Megahertz.
2.10 The Authority recognised civil Airworthiness Codes require aircraft VHF transmitters, receivers and transceivers to operate with a minimum channel separation of 25 kHz. To provide additional capacity for VHF communications in congested airspace, EASA has adopted reduced VHF channel separation to 8.33 kHz. Lack of equipment with an 8.33 kHz channel separation capability could lead to the crew being unable to communicate with ATC or other airspace users. Operations in European civil airspace therefore may be restricted unless VHF equipment having 8.33 kHz separation is installed.
2.11 Design Requirement (Essential). Data link communications used for traffic detection, separation and collision avoidance fitted to Defence aircraft must satisfy the civil standard applicable to operations in the associated civil airspace.
2.12 Certain types of operations in civil airspace rely on data link communications systems to provide situational awareness or air traffic direction/advice to the crew. The lack of this communications equipment may lead to limited access to associated civil airspace or loss of crew situational awareness.
2.13 This section presents design requirements that are not prescribed by the Authority, but identify particular design issues that designers should consider when establishing requirements for Defence aircraft communication systems.
2.14 Capability design requirement. Defence aircraft communication systems should satisfy the functional requirements prescribed by coalition partners for intercommunications and mission/capability.
2.15 A number of communications systems, such as secure voice communications and data link systems, provide essential capability functions that support interoperability. Failure to identify requirements for these systems and ensure that adequate functionality is provided could result in coalition partner refusal to conduct joint operations with Defence aircraft, or incorrect identification of Defence aircraft as ‘hostile’ during operations. Consequently, designers should ensure that all communication systems and associated functionality necessary to support joint operations are identified and captured in Defence aircraft design requirements. The AFIC standards may provide designers with a baseline from which to derive communication requirements for Defence aircraft.
2.16 Capability design requirement. Where required, Defence aircraft communication systems should comply with the Emanations Security requirements detailed in Section 2 Chapter 4 Electromagnetic Environmental Effects.
2.17 Inadequate protection of voice or data communications from unauthorised interception may compromise Defence capability.
2.18 Further guidance on implementing the communications systems requirements prescribed in this chapter can be provided by the chapter sponsor.