Dual use communication, navigation and surveillance approach

Integrating legacy military aircraft in a highly collaborative ATM environment, at lower cost and with reduced technical impact, requires the judicious selection of one of the following approaches:

• equipage exemptions and special handling by ATC;
• re-use or adaptation of military avionics to sustain civil requirements (dual use);
• supplementary ground support (e.g.multilink);
• equip “as civil”.

Accommodation of military aircraft not compliant with ATM/CNS requirements based on equipage exemptions is hardly compatible with automation and may result in delays, re-routing and higher ATC workload.

Equipage exemptions and derogations may be required in some cases but must be justified by compelling technical or military imperative reasons and only used as last resort.

Military actors will face integration challenges, resulting from higher levels of automation and ATM modernisation, based on interoperability and technology convergence approaches that take advantage of the performance based nature of civil ATM/CNS requirements.

Some past studies quantified the potential impact of the European Single European Sky Research (SESAR) programme upon military in the range of several billions of euros if retrofit based on civil equipment was the approach for military aircraft compliance with civil requirements.

Retrofits may seem a more immediate compliance option but sound technical assessments and cost-benefit analysis may dictate a different approach.

The so-called dual use CNS approach is an affordable option to adapt military avionics to emerging concepts, such as trajectory management, performance-based navigation (PBN) and advanced surveillance.

The dual use CNS approach was recognised in the European ATM Master Plan and, to some extent, followed in SESAR research efforts. At EUROCONTROL, we aim to apply this concept to many of our research efforts.

Applying it, helps to develop technical solutions reutilising military capabilities to cope with civil ATM/CNS requirements taking into account their identified performance levels.

The Dual Use CNS approach has the potential of:

• enabling seamless operational handling of military flights,
• increased interoperability,
• avoiding duplicated equipage and
• severely reducing investments on CNS retrofits and cost.

Research initiatives are fundamental for these objectives.

Dual use CNS requires:

• sound obsolescence management practices including through the use of commercial off-the-shelf,
• incremental technology insertions that increase the intervals between capability changes/improvements,
• re-use of legacy hardware leveraged with enhanced (sub)components,
• re-writing of legacy software functionalities to adapt to new processing environment and
• use of software emulation to mitigate obsolete hardware.

The type of military aircraft considered determines the best approach for compliance:

Transport-type military aircraft, regularly operating in mixed controlled airspace, evidence higher levels of equipage from a civil ATM/CNS perspective. Such platforms normally target similar levels of equipage as for civil/commercial airline aircraft. Such aircraft types offer enough space and provisions for the technical integration of additional avionics.

Fighter aircraft are to a lesser degree suited to accommodate retrofit initiatives, in comparison to larger transport-type aircraft, due to its highly integrated avionics and reduced cockpit space.

The reutilisation of navigation systems can bring significant benefits to military operators when facing the modernization of civil aviation infrastructure even if it represents only one of the options to cope with such technology evolution challenges in the different phases of flight.

In the context of civil-military interoperability solutions for the optimal re-use of military capabilities, the use of inertial navigation systems can be consider as an aircraft enabler to meet stringent navigation requirements when operating as General Air Traffic (GAT). The suitability of the use of military inertial systems for State aircraft with a view to sustaining GAT operations in a PBN airspace is under assessment. This assessment pursues the use of military inertial systems to comply with technical requirements stemming from RNAV 1 and RNP 1 specifications.

The type of on-board capability will dictate potential room for civil-military harmonisation at system level as well as the need for defining medium/long-term equipage plans to perform precision approach and landing operations in a GAT operational environment.

Ground Based Augmentation System (GBAS) is a capability that might be deemed as a system option or as a compatible system technology in a medium- and long-term military strategy for approach and landing operations. The need for commonality with the current GNSS infrastructure steered the necessity for assessing the equivalence between GBAS and military Landing Differential GPS (LDGPS), since this capability is available in the Multi-Mode Receivers (MMR) of military fleets.

A preliminary technical assessment on the interoperability between LDGPS and single-frequency single-constellation GBAS showed the possibility of defining an interoperable military system that encompasses military and civil requirements. The identified technical measures pave the way for the maturation of performance targets and the initial definition of the operational concept, together with the design of the logical system architecture, which must lead to the analysis of the benefit and cost mechanisms that justify further Research and Development (R&D) activities.