Your Full Name
Address, Postcode
Email address
Date

The Safety and Airspace Regulation Group
Civil Aviation Authority
Aviation House, Beehive Ring Road, Crawley, West Sussex, RH6 0YR
Sent by email and recorded post

Re: Alleged Airspace Infringement — Aircraft G-XXXX — DD/MM/YYYY — Time UTC
CAA Reference: reference number if known
Subject Access Request (UK GDPR) and request for data preservation

Dear Sir or Madam,

I write following notification of an alleged airspace infringement involving my aircraft G-XXXX on date at approximately time UTC near location / airspace designation. I do not accept that the alleged infringement occurred as described.

In order to respond properly to this matter, I require disclosure of all relevant evidence. I therefore make the following requests.

1. Subject Access Request under the UK GDPR and Data Protection Act 2018
I formally request all personal data held by the CAA and/or NATS relating to aircraft G-XXXX / callsign callsign for the flight on date, including all radar plot and track data, all occurrence reports or MORs filed in connection with this incident, and any correspondence or records referring to me or my aircraft in connection with this matter.

2. Technical data request
In addition, I request the following specific data:
(a) The complete radar track data for G-XXXX for the period time from to time to UTC on date, including raw plot positions, Mode C altitude at each update, time of applicability, and track quality indicators;
(b) The documented Required Surveillance Performance specification for the radar installation(s) used — maximum horizontal positional error at 95th and 99th percentile, and at the range and bearing of the alleged infringement (CAP 670 SUR02.4–10);
(c) PSR Permanent Echo alignment check records and SSR Remote Field Monitor check records for the relevant installation for the 90 days prior to and including the incident date, including measured bearing and range errors and specified tolerances (CAP 670 SUR04.8–16; SUR05.32–47);
(d) Display map validation records for the airspace boundary in question — accuracy assessment, geodetic reference system used, and date of last validation (CAP 670 SUR11.121–134);
(e) System fault log, BITE records and performance deficiency log for the installation for 30 days either side of the incident date (CAP 670 SUR12.98–101);
(f) The QNH value recorded in the surveillance data processing system at the time of the incident;
(g) All ATC voice recordings on relevant frequencies for the period time from to time to UTC on date;
(h) Any controller occurrence reports or notes made in connection with the alleged infringement.

3. Data preservation
I ask that all of the above data be preserved immediately pending resolution of this matter, and that you confirm in writing which data has been preserved. If any data has already been deleted or is unavailable, please notify me.

I am also submitting a separate SRG1605 form to request a copy of the occurrence report as provided for in CAP 1404 Edition 6 (p.5).

I will provide my substantive response once I have had the opportunity to review all relevant evidence.

Yours faithfully,

Your Full Name
Pilot Licence No.: XXXXXX
Tel: telephone number

Your Full Name
Address
Date

The Safety and Airspace Regulation Group
Civil Aviation Authority
Aviation House, Beehive Ring Road, Crawley, West Sussex, RH6 0YR

Re: Alleged Airspace Infringement — G-XXXX — Date — CAA Ref: reference

Dear Sir or Madam,

I write in response to the allegation that my aircraft G-XXXX infringed airspace designation and class on date at approximately time UTC. The CAA alleges that my aircraft was X metres inside the lateral boundary / X feet above the ceiling / X feet below the floor.

I take airspace compliance seriously. Having reviewed the evidence carefully, I respectfully submit that the alleged infringement is not established to the standard required under the CAP 1404 process, for the following reasons.

1. The ICG's first question — whether an infringement occurred — cannot be confirmed by the evidence

CAP 1404 Edition 6 (p.11) identifies as its first evaluation consideration: "Can the ICG confirm an infringement actually occurred?" The radar data does not confirm this. The alleged penetration of X metres / X feet falls within the documented accuracy tolerance of the surveillance system used as the source of evidence against me.

2. The radar positional accuracy margin equals or exceeds the alleged infringement

The performance standards applicable to UK ATC surveillance systems are set out in CAP 670 (Air Traffic Services Safety Requirements), with reference to the EUROCONTROL ATM Surveillance System Performance Specification. For a surveillance system supporting a 3 NM terminal separation standard, the maximum permitted horizontal positional error is 463 metres (0.25 NM) at the 95th percentile. The alleged lateral penetration of X metres is within this tolerance. A fully compliant and well-maintained radar could place my aircraft inside the boundary by this distance when my true position was outside it, and still be operating within its certified specification.

3. The display map boundary is itself subject to a permitted positional error

CAP 670 SUR11.131 permits the airspace boundary as displayed on the controller's radar screen to be up to 450 metres (0.25 NM) from its true surveyed position. I have requested the map validation records for the relevant boundary. If those records confirm the boundary is accurately plotted, please identify the specific documentation. If they are not available, the positional accuracy of the displayed boundary cannot be assumed.

4. [IF APPLICABLE — GPS counter-evidence]

My aircraft was equipped with GPS device / EFB application. I enclose as Appendix A the full GPS track log for the flight, exported in GPX / KML format. GPS positional accuracy is typically ±5–15 metres at the 95th percentile — substantially more precise than ATC radar. This track shows my aircraft at no point inside the airspace designation. The closest approach to the boundary was approximately X metres outside at time UTC. I used a VFR moving map throughout this flight.

5. [IF VERTICAL CASE — altitude accuracy]

The alleged vertical infringement of X feet falls within the combined error budget of the Mode C altitude chain, including: Gillham code encoding tolerance of ±100 ft (up to ±200 ft at code transitions, per ICAO Annex 10 Volume IV); display quantisation in 100 ft increments; and altimeter instrument tolerance. A combined error of 200 ft or more in any individual Mode C readout is consistent with fully compliant operation. My aircraft's most recent transponder calibration and altimetry check records are attached as Appendix B.

6. Alignment and maintenance records

[Once records received, insert relevant findings here. Example:] The PE / RFM check records provided show a bearing error of X° / range error of X NM as at [date], which further undermines the reliability of the positional data at the range and bearing of the alleged infringement. [OR if not yet received:] The alignment check records and performance logs I have requested have not yet been provided. In their absence, the calibration state of the radar at the time of the alleged incident cannot be established.

Conclusion

The available evidence — radar data whose accuracy tolerance substantially exceeds the alleged margin of penetration — is insufficient to confirm that an infringement occurred within the meaning of CAP 1404. I ask that the matter be closed or, if it is to proceed, that the CAA identify with specificity the basis on which it contends the radar data is accurate to within X metres / X feet at this location and time.

I am engaged with the CAP 1404 process and prepared to provide any further information that may assist. I note that my right under CAP 1404 Ed. 6 (p.5) to comment on all material to be relied upon remains outstanding pending receipt of the full evidence requested in my letter of date of evidence request letter.

Yours faithfully,

Your Full Name
Pilot Licence No.: XXXXXX

Appendix A: GPS track export — device / date
Appendix B: Transponder / altimeter calibration records
Appendix C: other evidence