ACAS Collision Avoidance Systems

ACAS Collision Avoidance Systems ACAS - A generic term for all types of collision avoidance systems carried on board ac. Mandatory ICAO ACAS standard, which specifies what the ACAS system must be capable of and what ac must carry it. - Standard is to give warning of other transponder equipped ac (TA) and instructions to avoid (RA). - All turbine engined ac above 5700kgs MTOW or with a max approved capacity of more than 19 passengers must carry ACAS. TCAS - - one type of ACAS. - TCAS 2 version 7 is currently the only type of ACAS which meets the ICAO ACAS standard. - Onboard collision avoidance system - Can only detect transcending ac - Can only generate RAs against ac whose transponder is reporting its altitude. - Mandatory for flight crews to follow TCAS RAs (unless overriding safety reason for not doing so). TCAS types - *TCAS 1* - gives TAs against transponding ac but no RAs - Does not comply with ICAO ACAS requirement but many ac which are not mandated to comply do carry TCAS 1. *TCAS 2* - Gives Sas and vertical RAs (against Mode C and S equipped ac) and is ACAS compliant. It is constant being updated, latest version being V7.1 after Ueberlingen. *TCAS 3 and 4* - would give horizontal as well as vertical RAs but although planned have not yet been developed. TCAS 2 - TA = 45 seconds before collision. 'Traffic Traffic', visible display of conflicting traffic. RA = 30 seconds before c