Can an RA be generated against an aircraft that is not ACAS II equipped?
An RA can be generated against all aircraft equipped with an altitude reporting transponder (mode S or mode A/C ). The intruder does not need to be fitted with ACAS II. However, RAs are coordinated only between ACAS II equipped aircraft. Note that in the majority of cases only one aircraft will receive an RA (regardless of whether the intruder is ACAS II aircraft or not).
