Regulation 1332/2011 for laying down common airspace usage requirements and operating procedures for airborne collision avoidance


This Regulation imposes safety requirements on operators of aircraft registered in a EU Member State or registered in a third country and operated by an EU operator, and on operators of aircraft used by a third country operator within the European Union. It 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 (EASA ‘basic’ regulation) undertaking flights into, within or out of the European 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 EU 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.


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, it was considered necessary to upgrade the current airborne collision avoidance system software. Dedicated studies concluded that with the current airborne collision avoidance system software there is a probability of a mid-air collision risk of 2,7 × 10 –8 per flight hour. Therefore the current ACAS II version 7.0 is considered to be of an unacceptable safety risk.

The new software version of the airborne collision avoidance system (ACAS II) to avoid mid-air collision shall be implemented at all aircraft flying in the airspace covered by Regulation (EC) No 216/2008. To ensure the highest possible 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 install ACAS II containing the latest version of collision avoidance software.

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 is necessary to provide a realistic time for the aeronautical industry to adapt to this new Regulation taking into account the availability of new equipment.

ACAS II Collision Avoidance Logic version 7.1 Requirements

ACAS II Equipment – Performance Requirement

1. The following turbine-powered aeroplanes shall be equipped with collision avoidance logic version 7.1 of ACAS II:

  • aeroplanes with a maximum certificated take-off mass exceeding 5 700 kg; or
  • aeroplanes authorised to carry more than 19 passengers.

2. The above requirement shall not apply to unmanned aircraft systems.

3. Aircraft not referred to in (1) above, but which will be equipped on a voluntary basis with ACAS II, shall have collision avoidance logic version 7.1.

Operations – Use of ACAS II

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.

When an RA indication is produced by ACAS II:

(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.

ACAS II Training

Operators shall establish ACAS II operational procedures and training programmes so that flight crews are appropriately trained in the avoidance of collisions and competent in the use of ACAS II equipment.

Entry into Force

The requirements of this Regulation apply as of 1 March 2012. The provisions of this Regulation shall apply as of 1 December 2015 to aircraft with an individual certificate of airworthiness issued before 1 March 2012.

For the complete details about its entry into force and application and the special provisions applying to operators subject to Council Regulation (EEC) No 3922/91, read the full text of the Regulation:

Commission Regulation (EU) No 1332/2011 of 16 December 2011 laying down common airspace usage requirements and operating procedures for airborne collision avoidance and Commission Regulation (EU) No 2016/583 of 15 April 2016 amending Regulation (EU) No 1332/2011 laying down common airspace usage requirements and operating procedures for airborne collision avoidance


Further Reading

European Commission



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