Route 4 is a departure route for aircraft taking off from Gatwick toward the west. Soon after take-off aircraft wrap 180 degrees round to the right and heads east, flying close to areas of South Holmwood, Leigh, Redhill and Reigate. 

The CAA decision on the Route 4 Standard Instrument Departure routes Post Implementation Review in April 2017 has been quashed by the Court at the request of the CAA. 

The process to date has been complex. Before outlining what the court action means, it is worth explaining step by step how the current situation arose and why airspace around Gatwick – including Route 4 - has been redesigned.

Why does airspace need to be redesigned?

UK airspace was originally designed over 50 years ago and current capacity is approaching its limits.  To ensure that the UK can meet future demand, the Government Future Airspace Strategy sets out a plan to modernise airspace by using modern satellite technology for air navigation, as opposed to ground-based beacon technology.   

What does this mean for Gatwick Airport?

Gatwick – and all other UK airports – have or are in the process of redesigning their departure routes to be in line with UK policy so that aircraft can use new satellite-based navigation technology.

As such, in 2013 Gatwick sought the CAA's approval to implement changes to all nine of its departure routes and these changes were approved by the CAA in August 2013, following consultation carried out by Gatwick. 

Post Implementation Reviews

Following CAA approval of new route designs – and after they have been flown for a period of time – the CAA performs Post Implementation Reviews of all new routes.  This is done to assess whether the anticipated impacts and benefits of the airspace changes happened in practice.

In 2015 the CAA reviewed all nine of Gatwick’s redesigned departure routes and approved the majority.  They did however find that Route 4 had not delivered the aim of the airspace change and required Route 4 to be modified.  Minor changes were also required to two other departure routes.

Following the CAA’s finding on the redesigned Route 4, Gatwick submitted an amended Route 4 proposal which the CAA ratified following their Post Implementation Review in April 2017.

Legal challenge

A community group - Plane Justice – however sought a judicial review that challenged the CAA’s Post Implementation Review decision to ratify the revised Route 4 departure route. 

And following ‘detailed and lengthy investigations’ the CAA asked the court to quash their previous decision which brings us up to the present day.

Why did the CAA reverse their previous decision?

The reason the CAA felt it could not allow their Post Implementation Review decision to stand was that during the process of responding to litigation the CAA discovered that the historical changes to the conventional route were not for entirely the reasons originally identified.

The formal notification to Gatwick by the CAA is available to read online.  The letter states that during their investigation ‘it became apparent that magnetic drift was not the predominant factor causing displacement of Route 4 from the NPR. The CAA considered that it could not allow its decision to stand where such decision was based upon a misunderstanding of the relevant facts.’

Because this information was not previously available to either the CAA or Gatwick, the CAA considered that that the airport could not have conducted a proper consultation in 2016 and therefore it could not allow its decision to stand.

What is happening now? 

Route 4 Standard Instrument Departures remain in place but have a temporary status as was the case prior to the CAA’s decision in April 2017. Aircraft departing Gatwick and flying along Route 4 will continue to use these routes.

Gatwick initiated a new full Airspace Change Proposal (ACP) for Route 4 in December 2018. We expect to be able complete the CAA airspace change process and implement new Route 4 RNAV Standard Instrument Departures in the first half of 2021. Full details of all our airspace change can be found on the CAA’s airspace change portal [insert link into text:]; just enter ‘Gatwick’ into the search function.

We expect that the CAA will in due course draw to a close the 2012 airspace change on Route 4 and we are waiting for a CAA decision on this matter.

Route 4 historical information