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  • BSI Flex 1903 v2:2024-06 community preview

    This is an interactive version 2 of BSI Flex 1903. The aim of the standard is to create a lexicon of standard terms and acronyms used in this sector. Please note, content is still undergoing internal review and there may be minor changes at full publication.

    We welcome your engagement and comments on this version to help inform the development of the standard. We would also welcome general feedback including what terms could be considered for future versions and these can be made through our dedicated feedback page .

detect and avoid (DAA)



  • Definition

    capability to see, sense or detect conflicting traffic or other hazards and take the appropriate action


    NOTE 1 UK CAA, CAP 722, Unmanned aircraft system operations in UK airspace – Policy and guidance [13] describes the following as necessary DAA functions:

    • detect and avoid traffic (aircraft in the air and on the ground) in accordance with the Rules of the Air;
    • detect and avoid all airborne objects, including gliders, hang-gliders, paragliders, microlights, balloons, parachutists etc.;
    • enable the remote pilot to determine the in-flight meteorological conditions;
    • avoid hazardous weather; and
    • detect and avoid terrain and other obstacles.

    NOTE 2 UK CAA, CAP 722, Unmanned aircraft system operations in UK airspace – Policy and guidance [19]] lists the five sub-functions of DAA: detect, decide, command, execute, and feedback loop.

    NOTE 3 DAA can incorporate the use of various sensors, architectures, multiple integrated systems, a human-in-the-loop (3.1.87), human-on-the-loop (3.1.88) or no human involvement at all.

    NOTE 4 A DAA system can have distributed components (e.g. on the ground, in the air or aboard satellites) and be described according to where the DAA sub-functions are carried out as either airborne DAA (3.1.5), ground-based DAA (3.1.84) or hybrid DAA (3.1.91).


    [SOURCE: ICAO, Annex 2 to the Convention on International Civil Aviation, Rules of the Air] [20]

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