EN    EN EN 
EN 1   EN Draft 
COMMISSION REGULATION (EU) No …/2011 
of […] 
laying down common airspace usage requi rements and operating procedures for 
airborne collision avoidance   
(Text with EEA relevance) 
THE EUROPEAN COMMISSION, 
Having regard to the Treaty on the Functioning of the European Union,  Having regard to Regulation (EC) No 216/2008 of the European Parliament and of the 
Council of 20 February 2008 on common rules in th e field of civil aviation and establishing a 
European Aviation Safety Agency, and repe aling Council Directive 91/670/EEC, Regulation 
(EC) No 1592/2002 and Directive 2004/36/EC (
1), and in particular Articles 8(1), 8(5), and 
9(4) thereof, 
Whereas: (1) Safety requirements should be imposed on operators of aircraft registered in a Member 
State or registered in a third country and operated by a Uni on operator, and on 
operators of aircraft used by a thir d country operator within the Union. 
(2) Following a series of mid-air encounters in  which safety margins have been lost, 
including accidents in Yaizu (Japan) in  2001 and in Überlingen (Germany) in 2002, 
the current airborne collision avoidance system software should be upgraded. The 
studies concluded that with the current airborne collisi on avoidance system software 
there is probability of a mid-air collision risk of 2.7x10
-8 per flight hour. Therefore the 
current ACAS II version 7.0 is considered to be of an unacceptable safety risk. 
(3) It is necessary to introduce a new software version of the airborne  collision avoidance 
system (ACAS II) to avoid mid-air collision of all aircraft flying in the airspace 
covered by Regulation (EC) No 216/2008. 
(4) To ensure the highest possibl e safety standards, aircraft  which do not fall within the 
scope of the mandatory carriage requirement but were equipped with ACAS II prior to 
entry into force of this Regulation should in stall ACAS II containing the latest version 
of collision avoidance software. 
(5) In order to ensure that the safety benefits associated with the new software version are 
achieved, all aircraft need to be equipped as  soon as practically possible. However, it 
                                                 
(1) OJ L 79, 19.3.2008, p. 1.  
EN 2   EN is necessary to provide  a realistic time for the aeronautic al industry to adapt to this 
new Regulation taking into account th e availability of new equipment. 
(6) The Agency prepared draft implementing ru les and submitted them as an opinion to 
the Commission in accordance with Article  19(1) of Regulation (EC) No 216/2008.  
(7) The measures provided for in this Regulati on are in accordance with the opinion of the 
European Aviation Safety Agency Committee established by Article 65 of Regulation (EC) No 216/2008, 
HAS ADOPTED THIS REGULATION: 
Article 1 
Subject matter and scope 
This Regulation lays down common airspace us age requirements and operating procedures for 
airborne collision avoidance to be fulfilled by: 
(a) operators of aircraft referred to under Artic le 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 airs pace above the territo ry to which the 
Treaty applies as well as in any othe r airspace where Member States apply 
Regulation (EC) No 551/2004
2. 
Article 2 
Definitions 
For the purposes of this Regulation th e following definitions shall apply: 
(1) ‘airborne  collision  avoidance  system (ACAS)’ means  an aircraft system based on 
secondary surveillance radar (SSR) transponde r 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 a dvisories 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 main tain existing separation; 
 (4) ‘traffic advisory (TA) indication’ means an  indication given to the flight crew that the 
proximity of another aircra ft is a potential threat. 
                                                 
(2)  OJ L 96, 31.3.2004, p. 1.  
EN 3   EN Article 3 
Airborne Collision Avoidance System (ACAS)  
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 c onditions set out in that Article. 
Article 4 
Special provisions applying to operators su bject to Council Regulation (EEC) No 3922/91 
 
1. By derogation from provisions OPS 1.668 and OPS 1.398 of Annex III to Council 
Regulation (EEC) No 3922/913, Article 3 and the Annex to th is Regulation shall apply for 
operators of aeroplanes refe rred to in Article 1(a). 
2. Any other obligation imposed on air ope rators by Regulation (EEC) No 3922/91 as 
regards the approval, installati on or operation of equipment shal l continue to apply to ACAS 
II. 
Article 5 
Entry into force and application 
1. This Regulation shall enter into force on the twentieth day following that of 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 provi sions 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, […] 
 For the Commission 
 The President 
                                                 
(3) OJ L 373, 31.12.1991, p. 4.  
EN 4   EN   
EN 5   EN ANNEX  
Airborne Collision Avoidance Systems (ACAS) II  
[Part-ACAS]  
Section I — ACAS II Equipment  
AUR.ACAS.1005 Performance Requirement 
(1) The following turbine-powered aeroplanes sha ll be equipped with collision avoidance 
logic version 7.1 of ACAS II: 
(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 collis ion avoidance logic version 7.1; 
(3) Point (1) shall not apply to unmanned aircraft systems. 
Section II — Operations 
AUR.ACAS.2005 Use of ACAS II 
(1) ACAS II shall be used during flight,  except as provided in the Minimum Equipment 
List as specified in Annex III to Council Regulation (EEC) No 3922/91, in a mode that 
enables RA indications to be produced fo r the flight crew when undue proximity to 
another aircraft is detect ed, 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) When an RA indication is produced by ACAS II, :  
(a) the pilot flying shall immediately conf orm to the indications of the RA 
indication, even if this conf licts 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 term s of the acknowledged ATC instruction or 
clearance and ATC notified of the manoeuvre, or 
(ii) comply with any amended ATC clearance or instruction issued.  
EN 6   EN  
AUR.ACAS.2010 ACAS II Training 
Operators shall establish ACAS II operational procedures and trai ning programmes so that the 
flight crew is appropriately trained in the avoi dance of collisions and competent in the use of 
ACAS II equipment.