# Commission Implementing Regulation (EU) No 923/2012 of 26 September 2012 laying down the common rules of the air and operational provisions regarding services and procedures in air navigation and amending Implementing Regulation (EU) No 1035/2011 and Regulations (EC) No 1265/2007, (EC) No 1794/2006, (EC) No 730/2006, (EC) No 1033/2006 and (EU) No 255/2010 (Text with EEA relevance), Division SERA.13001: Operation of an SSR transponder

Extent: E+W+S+N.I.

(a) When an aircraft carries a serviceable SSR transponder, the pilot shall operate the transponder at all times during flight, regardless of whether the aircraft is within or outside airspace where SSR is used for ATS purposes.
(b) Pilots shall not operate the IDENT feature unless requested by ATS.
(c) Except for flight in airspace designated by the competent authority for mandatory operation of transponder, aircraft without sufficient electrical power supply are exempted from the requirement to operate the transponder at all times.

---
Source: https://www.legislation.gov.uk/eur/2012/923/annex/section/13/division/SERA.13001 (the official version)
Page: https://openlegislation.uk/eu-regulation-2012-923/annex/section-13/division-SERA.13001
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.