2.5 Failure of the Transponder 2.5.1 The pilot should notify ATC of a transponder failure prior to entering that airspace where a transponder is normally required. 2.6 Treatment of ACAS Resolution Advisories (RA) 2.6.1 On being notified that an aircraft, in controlled airspace, is manoeuvring in accordance with an RA, a controller should not issue instructions to that aircraft which are contrary to the RA as communicated by the pilot. Once an aircraft departs from the current ATC clearance in compliance with an RA, controllers cease to be responsible for providing separation between that aircraft and other aircraft affected as a direct consequence of the manoeuvre induced by the RA. However, when circumstances permit, the controller should endeavour to provide traffic information to aircraft affected by the manoeuvre. The controller’s responsibility for providing separation for all the affected aircraft resumes when a) the controller acknowledges a report from the pilot that the aircraft has resumed the current clearance orb) the controller acknowledges a report from the pilot that the aircraft is resuming the current clearance and issues an alternative clearance that is acknowledged by the flight crew.