DAA capability will be required for Remotely Piloted Air Systems (RPAS) operating Beyond Visual Line of Sight (BLOS) in controlled and uncontrolled / un-segregated airspace. It will be a key enabler to the successful integration of UAS into civil airspace. However, there are no agreed sets of user requirements  for small to large, fixed and rotary wing RPAS operating in the various classes of airspace. Although regulatory frameworks have been established in some countries for small RPAS and trials of larger RPAS,  the overarching regulations and standards are still being developed by national and international bodies such as ICAO, JARUS (on behalf of EASA) and EUROCAE. There is also a risk that DAA regulations will be developed without broad and relevant user input and a good understanding of potential DAA solutions. It is also apparent that there are a range of DAA solutions being developed by academia and industry, but without any properly defined user requirement or regulatory framework, such development is potentially risky and is likely to be at a slow pace. Until issues are addressed, lack of DAA capability will be a major barrier to RPAS integration into civil / un-segregated airspace.

The DAA workshop was therefore structured to bring together and facilitate discussion between senior representatives from commercial operators, government agencies and the military; specialists involved in civil and military regulatory activities in the UK, Europe and USA; and academia, small, medium and large companies designing and manufacturing small to large fixed wing and rotary wing RPAS and associated systems. The workshop format of a series of short subject matter presentations followed by an open discussion enabled the key issues associated with DAA requirements, regulations and potential solutions to be identified and captured for follow up action. These included:

DAA Requirements
Civil and military RPAS will be required to operate BLOS in controlled and uncontrolled airspace in the future; day, night, in extremes of temperature in all environments
Smaller civil and military RPAS are more likely to operate in uncontrolled un-segregated very low and lower level airspace; larger civil RPAS are likely to operate in controlled airspace; larger military RPAS are likely to operate in both controlled and uncontrolled / un-segregated airspace and some, depending on type, at very low altitudes
DAA requirements to date have been developed for fixed wing RPAS; these are unlikely to be fully applicable to rotary wing RPAS
They should be evidence based, relevant to the operational environment and should provide equal or greater levels of safety compared to manned systems

DAA Regulations
DAA is the combination of Safe Separation and Collision Avoidance (if safe separation fails)
In controlled airspace, safe separation will be provided by RPAS operators complying with Air Traffic Control (ATC) procedures and instructions; and in uncontrolled airspace the RPAS operator applying “rules of the air” based on his/her situational awareness
Regulations for controlled airspace will assume the vast majority of users will be “co-operative” and have appropriate systems (Transponder, TCAS, ADS-B etc.)
However, DAA solutions for controlled airspace will also have to cope with “un-cooperative” users caused by emergencies or airspace incursions in controlled airspace and RPAS having to enter uncontrolled airspace in case of emergency 
Regulations for uncontrolled airspace will have to assume that the vast majority of users (micro-light, gliders, general aviation etc.) will be “un-cooperative” not having any type of safe separation or collision avoidance system, nor ATC and be based on the “rules of the air”  
DAA regulations will therefore be easier to define for controlled airspace than for uncontrolled airspace and should be achievable in the shorter term 
Regulations will have to be consistent at National (e.g. UK, USA), Continental (e.g. EU) and International (ICAO level) 

DAA Solutions
UK government and industry has demonstrated a number of DAA technologies  for potential civil and military use as evidenced by ASTRAEA, Watchkeeper RPAS, UKMoD Sense to Avoid Data Collection, Selex-ES VigilX situational awareness system and a lightweight visual/radar based system developed by MBL, funded by the UK Technology Strategy Board,  for small / medium RPAS 
DAA solutions are likely to be a combination of technologies depending on the class of airspace; a System of Systems approach will probably be required to optimise the overall solution from an RPAS and ATC perspective
RPAS in controlled airspace will utilise existing and planned systems (Transponders, TCAS, ADS-B, ACAS (Next-Generation TCAS) etc.) and ATC infrastructure enhanced by airborne sensors such as electro-optic and radar
RPAS in uncontrolled airspace will require airborne solutions not reliant on ATC
Small / medium RPAS will require low cost, low size and weight DAA solutions
DAA solutions will need to be reliable
RPAS command and control (C2) communications systems need to provide the required C2 data-rates and availability without significant latency 
Automatic  avoidance manoeuvres may be required  to  cater for limitations in C2 communications
DAA solutions have the potential to improve the safety of manned systems; this may provide DAA solution developers with additional market opportunities and therefore a better business case for investment

At the conclusion of the workshop, participants agreed that there should be a follow-up event before the year-end to develop a consensus position on requirements, regulations and solutions to feed into EUROCAE Working Group 73. The aim is to accelerate the process of airspace integration by making use of the significant UK based demonstration activity that has taken place over the last two years. The initial activity will be to identify what types of RPAS are likely to operate in what classes of airspace; what the user requirements are; and what should be prioritised. Organisations or individuals wanting to be involved should contact the RAeS at conference@aerosociety.com stating their willingness to participate and their specific interest in doing so.

Words: Tony Duthie, MRAeS, RAeS UAS Specialist Group, Chair: Detect and Avoid Workshop 

RPAS Today and Tomorrow
If you were unable to attend the UAS group conference in June on the Opportunities and Challenges for RPAS you can purchase access to the conference presentations and audio here, or by contacting the Conference and Events Team (conference@aerosociety.com) 

Conferences and Events
15 October 2014