Letter from Martin Breen to the Mode S team

Dear Mode S Team

The consultation documents & meetings have so far not produced answers or updates on your web site that address the questions below. Would you please provide answers in good time for carefully considered responses to the consultation?

AIRSPACE INFRINGEMENTS

 

The CAA states that “One of the most significant current safety risks to UK aviation is the inadvertent or unauthorised penetration of controlled and reserved airspace, and it is a major issue currently being considered by the Airspace and Safety Initiative.”(ASI) 

The CAA subsequently states  “The infringement of Red Arrows airspace in 2005 & 2006, and the subsequent cancellation of certain displays, left many paying spectators particularly disgruntled.” 

The following statistics for Infringements resulting in Mandatory Occurrence Reports (MOR’s) for the years 2002 to 2007 is not in included in the Consultation document nor indeed is any explanation of the dramatic reduction in MOR’s of a severity to require investigation. 

 

By complete contrast NATS reports over 600 Infringements for 2007.

Some of these are said to result in “reduced separation”. This would appear to confirm that the safety layer provided by current radar separation standards is very effective.

Q1 A Bearing in mind the recent year on year reductions in Airspace Infringement MOR’s of a severity to warrant investigation, what evidence of specific risk is the CAA using to opine that – “One of the most significant current safety risks to UK aviation is the inadvertent or unauthorised penetration of controlled and reserved airspace ”

      B How many unauthorised, as opposed to inadvertent, penetrations of controlled and reserved airspace by aircraft operating transponders are represented in the above figures? 

 

Q2 As the Red Arrows infringements are included in this consultation document they are presumably considered very relevant to transponder carriage. What evidence does the CAA have that the quoted infringements of Red Arrows airspace –

1. could have been prevented by transponder carriage

OR

2. cancellation of the shows avoided by transponders

 

Q3 Which of the four proposed Options does the CAA believe could have avoided the Red Arrows infringements and/or ensured the shows could commence? 

Q4 What vertical, horizontal and risk parameters does NATS apply in recording an airspace infringement? 

Q5 What evidence and explanation does the CAA have to account for the 3-year trend of significant annual reductions in Infringement MOR’s requiring Investigation? 

Q6 There are no recommendations from the ASI included in the Consultation document. What formal recommendations have the ASI made to DAP regarding transponders? 

Q7 Please supply a copy of the relevant ASI reports & recommendations. 

Q8. If there are no relevant reports & quantified recommendations from the ASI, what is the justification for the CAA to pre empt these with proposals for extended transponder carriage as a necessary solution to Airspace Infringements? 

Q9 What recent evidence, does the CAA have, of glider Airspace Infringements resulting in Mid Air Collisions, MOR’s or Airprox reports that would justify, in terms of proportionality, gliders being included in the mandating of transponders in TMZs created to address Airspace Infringement risks? 
 

MODE S Consultation Document – Annex E lists “Relevant AAIB & UKAB Reports & Recommendations.” 

Annex E Item 1.Lists 16 “examples of UKAB Airprox reports ”

Two of these relate to the uninvented Low Power transponder for gliders and are also represented in Item 2. This leaves 14 examples of which none of the discussion & comment resulted in a formal “Safety Recommendation” relating to transponders. (To put this in context - In the last 10 years there have been over 1500 Airprox reports & the UKAB has issued 84 formal Safety Recommendations) 

Airprox no. 175/05 is one of the “relevant” examples cited by the CAA.

The only reference to transponders in this report is a comment by the PA28 pilot involved in the Airprox – “ He opined that it would probably help considerably if gliders were any other colour but white or had radios and transponders so they could participate in ATC.” 

The report subsequently states - “It was the unanimous view of the Board that this incident provided another example of the urgent requirement for the development of electronic collision warning systems and their fitment to light aircraft and gliders”.  

The CAA has repeatedly quoted Airprox reports and recommendations to justify its proposals. In particular it states in 12.5 “The CAA must consider and, where appropriate, act upon relevant reports and recommendations from such bodies as the Air Accident Investigation Branch (AAIB) and the UK Airprox Board  (UKAB).” 

Q10 As both the glider and the aircraft were visible on Radar and Transponders do not provide electronic collision warning between gliders and light aircraft; why specifically does the CAA cite this report to be relevant to its Transponder policies and options? 
 

Q11 What “urgent” action did the CAA take to promote the development of collision warning systems suitable for fitment to light aircraft and gliders as a result of this “relevant” Airprox recommendation? 

Annex E Item 3. says - “The AAIB has made a recommendation to the CAA concerning the use of SSR transponders with altitude information (AAIB Recommendation 99-34)”

This recommendation dates from 1999. In fact it reads – “The CAA should include in its safety programme the following advice (6 items are listed) to GA operators who plan to use the low level airspace:

d. The routine use of the radar transponder, including height information.” (The other five suggestions do not relate to transponders.)

This is “advice” in relation to a nine-year-old safety presentation not a recommendation to “mandate” any of the CAA’s transponder proposals. 

Not mentioned at all are AAIB Recommendations 2005-06 & 2005-08 (both six years later) in relation to glider, helicopter and microlight collision fatalities–

2005-06 “It is recommended that the CAA should initiate further studies into ways of improving the conspicuity of gliders and light aircraft, to include visual & electronic surveillance means, and require the adoption of measures that are likely to be cost effective in improving conspicuity.” 

2005-08 “It is recommended that the CAA should promote international co-operation and action to improve the conspicuity of gliders and light aircraft through visual and electronic methods.” 

The CAA repeatedly rejected these recommendations stating - “………particularly in the light of impending wider transponder carriage.” 

Q12 How would the CAA’s “wider transponder carriage” proposals have provided the necessary electronic conspicuity to minimise the risk of these collisions and future similar collisions? 

Q13 Is the CAA now prepared to take concerted action on these AAIB recommendations and the recommendation in Airprox report 175/05? 

Annex E Item 2. Says “The UKAB has issued a safety recommendation concerning the carriage and operation of transponders in gliders (UKAB safety recommendation 186/05-02)” –

186/05-02 (3 years ago) reads - “The CAA should continue to promote and with renewed urgency the production of a lightweight transponder and, when available, consider mandating its carriage and use in gliders.”  

In the December 2007 update of Airprox 186/05-02 published by the UKAB, the CAA states – “Work on LPST development by several companies continues.”  

In Para 3.5 of “The Full RIA for a proposal for Phase 1” published shortly before the Phase 2 Consultation, the CAA states “The LPST is undoubtedly a significant element of the proposals and the CAA has been working with industry for several years to encourage the development of a transponder suitable for these types of aircraft.” 

All my attempts to pre-order a low power transponder for my glider have been unsuccessful and AFE Oxford (Transponder retailers) advise that there are no Companies developing such equipment. 

Q14 Who are the companies the CAA refers to its December 2007 update? 

Q15 What evidence is there of the current stage of development of Low Power transponders? 

Q16 Does the CAA now have any evidence of any trials relating to Low Power transponders that are not mentioned in the consultation document?  

Q17 If the “significant element” of the CAA’s phased proposals (i.e. LPST) is not being developed, then phases towards a widespread safety layer depending on ACAS in Class G Airspace is severely flawed. What justification is there to implement the Phase 2 Options now, and impose significant costs on GA, at a time that the full potential of other collision warning systems, i.e. available and developing GPS based collision warning & data link systems, usable by aircraft for which there is no transponder, have not been thoroughly re-considered and evaluated?

MODE S Consultation Document Para 12.5

“Moreover, the UKAB has previously advised the CAA that it fully supports the proposals to mandate the equipage of Mode s transponders on all aircraft operating in the UK FIR to the maximum extent possible as permitted by available technology.”

The Airprox Board has never published this as a safety recommendation.

Neither the CAA nor the Airprox Board has published the document containing this advice.  

Q18 Please supply a copy of the full document containing this recommendation from the Airprox Board in order that it can be considered in context.

The CAA’s Objectivity in relation to transponders.

 

Consultation document Page vi – “However, the CAA has four other key priority areas in the use of SSR transponders that it considers should be adopted in the next phase of any expansion in the use of Mode – S.” 

In considering the objectivity & credence of the CAA’s proposed Phase 2 Transponder priorities and timescale it is pertinent to consider whether the CAA is prone to overstate the necessity of its transponder proposals.

In the 2006 transponder consultation document the CAA states -

“As safety is the highest priority in aviation any safety improvements will, therefore need to be put in place before air traffic levels can be allowed to increase.” 

Q19 What measures did the CAA or DfT implement to prevent Air traffic levels increasing? 

Q20 How many CAT operators has the CAA or DfT prevented from flying in Class G Airspace due to the lack of safety improvements? 

Q21 How many CAT operators have notified the CAA or DfT that they will not commence operations or increase operations through class g airspace until there are further safety improvements? 

OPTION 1

The Phase 1 mandate of Mode-s transponders has ensured that radar spectrum capacity will not be exceeded and the use of Mode a/c transponders will not increase but instead decrease. 

The CAA says that Mode-s is backwards and forwards compatible with Mode A/C. 

Mandating Class D airspace, which already provides an ATC “known environment”, will burden owners of Mode A/C equipped aircraft to change to mode-s and effectively exclude numerous recreational aircraft for which there are no mode s transponder. 

Q22 What key safety benefits would mode-s provide over Mode A/C in the already known environment of Class D airspace? 

Q23 What measures could the CAA implement to ensure that aircraft unable to carry Mode S would not be unnecessarily denied access to Class D Airspace? 

Thank you 

Martin Breen