This is the CAA home page for Mode S information. (Updated December 2009)
New Transponder Carriage Requirements
Following public consultation, the revised transponder carriage requirements came into effect on 1 January 2010 with the publication of the Air Navigation Order 2009. The revised carriage requirements are published here.
To register for the Mode S Phase 1 General Exemption please complete form DAP 1901. Please note, this exemption does NOT apply to IFR flight in Notified EHS airspace, currently the London TMA. Contact
Details of the Mode S carriage requirements for GA in Europe are available from the Eurocontrol General Aviation VFR Briefing Room.
The CAA has been encouraging the development of a portable Low Power SSR Transponder (LPST) for use on light and very light aircraft that may experience difficulty in installing higher power transponders. In support of this work the CAA has taken a leading role in developing and sponsoring various studies into the subject. Links to LPST reports can be found under the LPST Documents heading, in the Documents section.
General Mode S enquiries can be submitted to firstname.lastname@example.org.