
Article 1 
This Regulation lays down common airspace usage requirements and operating procedures for airborne collision avoidance to be fulfilled by:

((a)) operators of aircraft referred to under Article 4(1)(b) and (c) of Regulation (EC) No 216/2008 undertaking flights into, within or out of the Union; and
((b)) operators of aircraft referred to under Article 4(1)(d) of Regulation (EC) No 216/2008 undertaking flights within the airspace above the territory to which the Treaty applies as well as in any other airspace where Member States apply Regulation (EC) No 551/2004 of the European Parliament and of the Council.
Article 2 
For the purposes of this Regulation the following definitions shall apply:

((1)) ‘airborne collision avoidance system (ACAS)’ means an aircraft system based on secondary surveillance radar (SSR) transponder signals which operates independently of ground-based equipment to provide advice to the pilot on potential conflicting aircraft that are equipped with SSR transponders;
((2)) ‘airborne collision avoidance system II (ACAS II)’ means an airborne collision avoidance system which provides vertical resolution advisories in addition to traffic advisories;
((3)) ‘resolution advisory (RA) indication’ means an indication given to the flight crew recommending a manoeuvre intended to provide separation from all threats or a manoeuvre restriction intended to maintain existing separation;
((4)) ‘traffic advisory (TA) indication’ means an indication given to the flight crew that the proximity of another aircraft is a potential threat.
Article 3 

1. The aeroplanes referred to in Section I of the Annex to this Regulation shall be equipped with and operated in accordance with the rules and procedures as specified in the Annex.
2. Member States shall ensure that operation of aeroplanes referred to in Article 1(2)(a) of Regulation (EC) No 216/2008 comply with the rules and procedures specified in the Annex in accordance with the conditions set out in that Article.
Article 4 

1. By derogation from provisions OPS 1.668 and OPS 1.398 of Annex III to Regulation (EEC) No 3922/91, Article 3 and the Annex to this Regulation shall apply for operators of aeroplanes referred to in Article 1(a).
2. Any other obligation imposed on air operators by Regulation (EEC) No 3922/91 as regards the approval, installation or operation of equipment shall continue to apply to ACAS II.
Article 5 

1. This Regulation shall enter into force on the 20th day following its publication in the Official Journal of the European Union.
2. Articles 3 and 4 shall apply as of 1 March 2012.
3. By way of derogation from paragraph 2, in the case of aircraft with an individual certificate of airworthiness issued before 1 March 2012, the provisions of Article 3 and 4 shall apply as of 1 December 2015.
This Regulation shall be binding in its entirety and directly applicable in all Member States.Done at Brussels, 16 December 2011.
For the Commission
The President
José Manuel BARROSO
ANNEX
Airborne collision avoidance systems (ACAS) II  Section I —  AUR.ACAS.1005  (1) 

((a)) aeroplanes with a maximum certificated take-off mass exceeding 5 700 kg; or
((b)) aeroplanes authorised to carry more than 19 passengers.
 (2) Aircraft not referred to in point (1) but which will be equipped on a voluntary basis with ACAS II, shall have collision avoidance logic version 7.1.
 (3) Point (1) shall not apply to unmanned aircraft systems.
 Section II —  AUR.ACAS.2005  (1) ACAS II shall be used during flight, except as provided in the minimum equipment list as specified in Annex III to Regulation (EEC) No 3922/91, in a mode that enables RA indications to be produced for the flight crew when undue proximity to another aircraft is detected, unless inhibition of RA indication mode (using TA indication only or equivalent) is called for by an abnormal procedure or due to performance limiting conditions.
 (2) 

((a)) the pilot flying shall immediately conform to the indications of the RA indication, even if this conflicts with an air traffic control (ATC) instruction, unless doing so would jeopardise the safety of the aircraft;
((b)) the flight crew, as soon as permitted by workload, shall notify the appropriate ATC unit of any RA which requires a deviation from the current ATC instruction or clearance;
((c)) when the conflict is resolved, the aircraft shall:

((i)) be promptly returned to the terms of the acknowledged ATC instruction or clearance and ATC notified of the manoeuvre; or
((ii)) comply with any amended ATC clearance or instruction issued.
 AUR.ACAS.2010 
Operators shall establish ACAS II operational procedures and training programmes so that the flight crew is appropriately trained in the avoidance of collisions and competent in the use of ACAS II equipment.
