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Gatwick Modified Route 5 (Runway 08 RNAV-1 Standard Instrument Departure Procedures) Post Implementation Review


The purpose of the Post Implementation Review (PIR) is for the CAA to assess whether the change has delivered the anticipated impacts and benefits set out in the original airspace change proposal and decision, and if not to establish why and determine the most appropriate course of action.

Data received from Gatwick Airport Limited (GAL) for the period 30 March 2017 to 30 September 2017 was been published along with this Guide to the PIR Data. Stakeholders had until 19 March 2021 to submit evidence or views on the data.

Our PIR report was published on 17 November 2021. This sets out the framework within which the review has been conducted and details the data that has been analysed in order to reach the conclusions on whether the minor modification of the Route 5 design is a better replication than that achieved by the original Route 5 RNAV-1 SID implemented in November 2013.

Last updated: 17 November 2021

PIR data

Publication of our report

Update on the Gatwick Route 4 Post Implementation Review

Following the analysis of the feedback received in the feedback exercise at the beginning of this year, we have published the final report (CAP1912) of the post implementation review (PIR) of Gatwick Airport Limited’s Route 4 RNAV-1 SID Airspace Change Proposal.

We have also published the analysis of feedback received during the feedback exercise as an annex to CAP1912.

Gatwick Airport Limited have responded to the final post implementation review with this formal response. We have written this reply requesting additional information.

The CAA have had two meetings with NATS and Gatwick Airport Limited (GAL) on 03/07/2020 and 05/08/2020 to discuss the additional information requested and to address further supplementary questions regarding Gatwick’s proposed implementation of CAP 1912. The minutes of the these two meetings are combined for continuity. The CAA accepts these minutes as a fair reflection of the conversations which took place. The CAA is still considering the timeframes and technical requirements identified within these minutes by GAL, ANS and NATS and whether it accepts the rationale presented.

The CAA has considered the timeframes and technical requirements discussed with GAL, ANS and NATS, and has replied with this formal response. Whilst the CAA accepts that a single adaptation change is the more desirable solution, we would not expect the timeline for the implementation of CAP 1912 and the denotification of the RNAV SIDs to extend beyond AIRAC 02/2021. The CAA does not accept the proposed rationale for the continued publication of the BIG RNAV SID as currently published in the AIP.

Last updated: 22/09/2020

PIR publication process

In November 2014 we commenced the Post Implementation Review (PIR) of the November 2013 changes to the standard instrument departure routes (SIDs) at Gatwick which enabled the use of modern satellite technology for air navigation for the first time.

The purpose of the PIR is for the CAA, as the independent regulator, to assess whether the change has delivered the anticipated impacts and benefits set out in the original airspace change proposal and decision, and if not to ascertain why and determine the most appropriate course of action.

Our PIR report was published on 11 November 2015. Following the conclusion of the PIR, the CAA advised the sponsor of the outcome of the CAA review (see below). A number of requirements for modifications to Routes 2, 4 and 5 were provided to the sponsor, together with technical recommendations regarding how a better replication may be achieved

Data provided

Airspace change proposal, analysis and decision process

The documents referred to will be published as soon as possible after the CAA receives them unless otherwise stated.

Framework briefing held with organisation(s) considering proposing the change

8 Nov 2011
23 Apr 2012

Formal airspace change proposal submitted by organisation requesting the change

30 Nov 2012 (v1.0)
9 Jan 2013 (v1.1)

Airspace change proposal
Our decision to make the change

Decision letters

14 Aug 2013 CAA Decision letter to NATMAC


CAA decision letter to Gatwick Airport Limited

Operational report including our analysis on airspace
safety and efficiency

Operational report

Supplementary operational support

Environmental report   CAA Environmental assessment
Consultation report   CAA Consultation assessment
CAA Information Notice 15 Aug 2013 CAA Information Notice
AIP amendment published 5 Sep 2013 NATS announcement
Implementation date of the change 14 Nov 2013  
Close Airspace change proposal, analysis and decision process

Post implementation review initiated

Scope and objectives of the review determined and our confirmation of the data requirements issued to the organisation that requested the change 7 Nov 2014 CAA PIR letter
We have not revised the scope and objectives of the review    

We have requested more information from the organisation that requested the change

29 Jan 2015 and 24 June 2015
CAA Information request
Close Post implementation review initiated

Data collection and analysis by the organisation that requested the change

Data is sent to us
Due between
14 Dec 2014 and 5 Jan 2015
Received 12 Jan 2015
Close Data collection and analysis by the organisation that requested the change

Our assessment

Our assessment of the completeness and adequacy of the data submitted
Started 14 Jan 2015  
Completed 20 Apr 2015  

Further data sent to us by the organisation that requested the change

Due 6 Feb 2015  
Received 6 Feb 2015
  20 Feb 2015
  13 Apr 2015
/requested from operators
Started 3 Nov 2014 Stakeholder Feedback
Completed 7 May 2015 See Annex 3 of CAP 1346
Feedback requested from the ANSP    
Started 9 July 2015 CAA Information Request
Completed 10 July 2015 NATS reply to vectoring questionnaire
Our analysis of written feedback from people and organisations other than airlines, other aircraft operators, airport operators and air navigation service providers
Started 6 Jan 2015  
Completed 29 Jun 2015  
Close Our assessment

Our data analysis phase

Operational impact review
Started 9 Feb 2015
Completed 29 Jun 2015
Environmental impact review  
Started 14 Jan 2015
Completed 29 Jun 2015
Our consideration and determination of any appropriate consequential action
Started 29 Jun 2015
Completed 28 Sep 2015
Close Our data analysis phase

PIR conclusions

Communications with Change Sponsor

Requirements and recommendations letters 28 Sep 2015 Modification requirements letter to Gatwick
  01 Oct 2015 Modification recommendations to meet requirements letter to Gatwick
  10 Oct 2015 CONV SID Requirements Letter

Publication of our report

We share our report in final draft with the organisation that requested the change, in confidence. This is not an opportunity for them to amend our conclusions but a check for errors.

Final draft to the organisation that requested the change    
Sent 28 Oct 2015  
Comments due 29 Oct 2015  
Received 29 Oct 2015  
Report published 11 Nov 2015

Report of the CAA's Post Implementation Review of the Implementation of RNAV-1 Standard Instrument Departures at Gatwick Airport

Access the six annexes to this report

  • Annex 1: Route analysis (nine separate reports)
  • Annex 2: Environmental Analysis report
  • Annex 3: Operational and Technical report
  • Annex 4: PIR Correspondence Assessment
  • Annex 5: Correspondence database
  • Annex 6: CAA IFP Recommendations report


Current position regarding modification requirements

10 May 2016 - All Departure routes (Conventionsl SIDs), Routes 2 and 5, Route 4

All Departure routes Conventional SIDs

Gatwick has not yet submitted the modifications to these routes required by the CAA.

Routes 2 and 5

Gatwick has submitted revised designs to the CAA.

The designs have been returned to Gatwick for further procedure design work and re-submission to the CAA.
There is no estimate yet when the revised routes will first be flown. However, at time of writing (10 May 2016) this not anticipated to be sooner than 13 October 2016.

Gatwick will carry out a similar community engagement programme in respect of these modifications once the designs have been validated by the CAA.

Route 4

Gatwick has submitted to the CAA a revised design to meet our requirements dated 28 September 2015. The CAA has validated that the design meets international design requirements.

They published the revised design on its blog on 24 March 2016 which has since been updated. 

Gatwick delivered leaflets to 30,000 households, placed advertisements in local papers and held two drop-in sessions for members of the public also in March 2016.

The revised designs will begin to be flown from 26 May 2016 and monitored for 6 months.

Gatwick will be required to collate feedback received on those routes during that time and submit it to the CAA as part of that monitoring exercise.

Comments about the use of Route 4 should be sent to Gatwick during this period at route4@gatwickairport.com.

Route 4 possible alternate design (option for strong wind conditions)

In addition to the re-design work outlined above, in order to meet our modification requirements dated 28 September 2015, Gatwick is also considering whether it is possible to develop a re-design that is only used in strong wind conditions.

This possibility is being considered by Gatwick in conjunction with the airline operators and Air Traffic Control at Gatwick Airport and NATS Terminal Control at Swanwick.

If an appropriate RNAV SID design and air traffic control operational procedures can be developed, Gatwick will submit a design to the CAA as part of this PIR process.

Close 10 May 2016 - All Departure routes (Conventionsl SIDs), Routes 2 and 5, Route 4

16 September 2016 - Update on re-designed Route 4

The revised Route 4 design was implemented on 26 May and will be operated and monitored for six months. At the end of that monitoring period the revised design will remain operational whist the CAA considers the data collected during that monitoring phase. The CAA will make and publish its decision whether or not the modified design is acceptable as soon as possible. We hope that this will be within three to four months.

The objective of the re-design is set out in our letter to GAL dated 23 May 2016 which is available on our website (link above, under 23 May entry). In addition to the operational requirements of any SID, the objective of the modification requirement is that aircraft tracks replicate the nominal track of the conventional SID adjusted for magnetic variation.

We will assess where the data shows aircraft are flying and whether they are flying where we anticipated them to be after these modifications. We will use radar track data and the feedback received from local residents to assess this. GAL are tasked with collating both types of data and providing it to us during and at the end of the monitoring phase.

Close 16 September 2016 - Update on re-designed Route 4

29 November 2016 - End of Route 4 monitoring period

The Route 4 monitoring period of 6 months has come to an end; once GAL provide the CAA with the final data for November, the CAA will commence the PIR review. A decision on whether the modified design is acceptable is expected within three to four months. Until a decision is reached, the modified Route 4 will remain in operation.

Close 29 November 2016 - End of Route 4 monitoring period

22 December 2016 - Route 2, Route 4 and Route 5

Route 2

We are continuing to assess the large volume of data which appears to indicate that, over time, the slight ballooning in the turn has been reduced.

Route 2 PIR conclusion: The CAA concluded that the track keeping performance of departures had improved and no further action was required.

Route 4 RNAV1 SID

The Route 4 data for 6 month utilisation up to 26 November 2016 of the revised Route 4 RNAV1 SID has now been provided to the CAA by GAL, including all the feedback received during that period. The CAA is currently analysing that data.

Route 4 Conventional SID

The 5 year review design for the conventional SID was submitted to the CAA on 15 November 2016 but returned to the design organisation as it did not comply with the regulatory requirements, as previously supplied to GAL. A further revision was supplied to the CAA on 13 December. The CAA is currently assessing that reviewed design.

Route 5

The revised Route 5 design required by the CAA as an outcome of the PIR (as set out in our letter) has been submitted to the CAA for approval. The design has now been approved for operation and will be flown from 30 March 2017. The CAA will require GAL to monitor the operations for 6 months and provide the data to the CAA.

Route 5 update: PIR data for the modified RNAV SID has been received by the CAA. The CAA will review this data, and will publish the outcome of the PIR together with the data received from Gatwick as soon as our review is complete. No dates have been set for the completion of this work.

Close 22 December 2016 - Route 2, Route 4 and Route 5

7 April 2017 - CAP 1531: CAA conclusions in respect of modification requirements relating to Route 4 RNAV1 SIDs and correction requirements relating to Route 4 Conventional SIDs; CAP 1531 was subsequently revoked on 7 February 2018, retained for reference here along with the following annexes and attachments:

Latest developments

10 May 2018 - letter to GAL outlining the historic copies of the UK AIP showing changes to traffic flying over Route 4 over time:

We aim to publish the full contents of all documents received by us during the change process. Occasionally it will be necessary for us to consider, under our Environmental Information Regulation obligations, whether some information can be disclosed, balancing the rights of the owners of the information against the public interest in transparency, especially information which is commercially confidential or protected by intellectual property rights.

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