What's New? (updated 1 Apr 2008)
**Phase 2 Consultation Presentation Events** As part of the current consultation on the proposals to expand Mode S the CAA is holding a number of presentation events.  The aim of the events is to present the Phase 2 proposals and to answer any questions relating to the content of the consultation material. Thursday 20 March 2008, 1900hrs, Scottish Gliding Club, Portmoak Friday 4 April 2008, 1900hrs, Lasham Gliding Club Friday 11 April 2008, 1900hrs, Wolds Gliding Club, Pocklington Monday 21 April 2008, 1900hrs, The Gliding Centre, Husbands Bosworth
How the Mode S ELS expansion phases could affect you - an interactive guide.  This online guide enables operators of aircraft less than 5700kg (MTOM) or maximum cruising TAS capability of less than 250kts to work through the applicability of the current Mode S ELS regulations and Phase 2 expansion proposals based on the type of aircraft you operate and how and where you use it.  Based on the choices you make, the guide will indicate whether or not you may need to fit a Mode S transponder. Please note, exemptions referred to in this guide do NOT apply to IFR flight in Notified EHS airspace, currently the London TMA.
**Phase 2 Consultation** Formal consultation on the CAA Phase 2 Mode S Proposals, “PROPOSAL FOR AN INCREMENTAL EXPANSION OF THE USE OF SECONDARY SURVEILLANCE RADAR MODE SELECT TRANSPONDERS IN UK AIRSPACE”, began 31 January 2008.  Click here for more information and a link to the consultation material.
**Phase 1 Exemption Registration** 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.

Mode S EHS Latest
Within the UK FIR, Mode S Enhanced Surveillance (EHS) has been mandatory for all aircraft flying IFR as GAT within notified Mode S airspace since 31 March 2005.  The two-year transition that accompanied the introduction of the EHS carriage requirements came to an end on 31 March 2007.  The EHS mandate applies to specified busy terminal and en route airspace.  The bounds of the airspace are promulgated in the UK Aeronautical Information Publication, AIP GEN 1-5-3.  Currently the notified airspace is confined to the London TMA, but it is expected to expand into other busy major en-route and terminal airspace by 2009.  The CAA will seek to provide up to 18 months notice of changes to EHS airspace, however no further consultation will be conducted as it was covered in the original consultation for EHS.

The EHS mandate applies only to IFR GAT flight within the designated airspace.  Aircraft above 5700kg or with a maximum cruising True Airspeed greater than 250kts are required to be EHS equipped unless technically non-capable.  Helicopters and other aircraft operating IFR within this airspace are required to be Elementary Surveillance (ELS) equipped.  Further details are contained within the AIP GEN 1-5-3 (AIRAC Cycle 3/2008, effective 13 March 2008).  Click here for an extract, which is also available under the Documents section.

Mode S ELS Phased Approach
At the time of the consultation and subsequent introduction of the EHS mandate, the CAA stated its intention to propose a further expansion of Mode S ELS on aircraft operating in the remaining UK airspace from March 2008.  This was the subject of a public consultation and Partial Regulatory Impact Assessment (RIA) process during 2006.  Subsequent to the Partial RIA, it was decided to develop a phased approach to further implementation of Mode S Elementary Surveillance (ELS). 

Phase 1 makes Mode S the technical means of compliance for the current transponder carriage rules.  Based on the results of the public consultation that accompanied the 2006 Partial RIA, a Full RIA to, ‘AMEND THE AIR NAVIGATION ORDER 2005 FOR THE PURPOSE OF EXPANDING THE USE OF SSR MODE S TECHNOLOGY IN UK AIRSPACE' was submitted to the Secretary of State for Transport.  This proposal has been accepted and comes in force from 31 March 2008, for further details click here.

In Phase 2 the CAA proposes to extend the rules for carriage and operation of transponders, which as result of Phase 1 will be Mode S by default.  The CAA began public consultation on Phase 2 on 31 January 2008.  The Phase 2 consultation closes at 1700hrs on 31 May 2008.  For further details click here.

Current & Proposed Transponder Carriage Rules In UK Airspace

Operating Scenario	Current Rules After Mode S Phase 1 Expansion (31 March 2008)	Proposed Rules After Mode S Phase 2 Expansion (31 March 2009)	Effect of Change
Within Controlled Airspace below FL 100	Mode S Elementary Surveillance required for IFR flights except by gliders, SSGs, hang gliders and paragliders	Mode S Elementary Surveillance required for all flights	VFR flights and all flights by gliders, SSGs, hang gliders and paragliders would now require Mode S Elementary Surveillance
Within all airspace at and above FL 100 and below FL 195	Mode S Elementary Surveillance required for all flights except by gliders, SSGs, hang gliders and paragliders	Mode S Elementary Surveillance required for all flights except gliders, SSGs, SLMGs, hang gliders and paragliders when operating within notified Transponder Free Zones (TFZ)	Gliders, SSGs, SLMGs hang gliders and paragliders would now require Mode S Elementary Surveillance except when within a TFZ
Within all airspace at and above FL 195	Mode S Elementary Surveillance required for all flights except by gliders and SSGs operating within notified Temporary Reserved Airspace for gliders (TRA(G))	Mode S Elementary Surveillance required for all flights except by gliders, SSGs and SLMGs when operating within notified Temporary Reserved Airspace for gliders (TRA(G))	SLMGs would be given an exemption to now be treated the same as gliders and SSGs.
Within Transponder Mandatory Zones (TMZ) e.g. Scottish TMA between 6000 ft ALT and FL 100	Mode S Elementary Surveillance required for all flights except by gliders, SSGs, hang gliders and paragliders	Mode S Elementary Surveillance required for all flights	Gliders, SSGs, hang gliders and paragliders would now require Mode S Elementary Surveillance
All flights across international boundaries	Mode S Elementary Surveillance not required when crossing international boundaries from the UK, but may be required in the other European State into which the aircraft is transiting.	Mode S Elementary Surveillance required for all flights by aeroplanes and helicopters	All aircraft except gliders, SSGs, SLMGs, hang gliders and paragliders would now require Mode S Elementary Surveillance
All flights for the purposes of public transport	Mode S Elementary Surveillance required except for balloons, gliders, SSGs, hang gliders and paragliders	Mode S Elementary Surveillance required except for balloons, gliders, SSGs, hang gliders and paragliders	No change
Within notified Mode S Enhanced Surveillance Airspace e.g. London TMA	Mode S Enhanced Surveillance required for all fixed-wing aeroplanes operating under IFR having a maximum take-off mass in excess of 5,700 kg or having a maximum cruising true airspeed in excess of 250 knots. Mode S Elementary Surveillance is required for all other aircraft.	Mode S Enhanced Surveillance required for all fixed-wing aeroplanes operating under IFR having a maximum take-off mass in excess of 5,700 kg or having a maximum cruising true airspeed in excess of 250 knots. Mode S Elementary Surveillance is required for all other aircraft.	No change

Contact
General Mode S enquiries can be submitted to mode.s@caa.co.uk.  For details on how to respond to the current Phase 2 consultation, including by e-mail, click here.