At the start of October 2017, the Civil Aviation Authority (CAA) commenced a Post-Implementation Review of the introduction of RNAV at Luton Airport. The new GPS-based navigation system was introduced first on the busiest route carrying the westerly departures which track south and then east between St Albans and Harpenden.
RNAV introduction was not without its problems: early on it became clear that actually the new navigation system did not cope particularly well on a route with a short straight section between two curves: when it was windy, the planes veered off track. Also, it took over a year for the system to be adjusted so that Boeing aircraft would reliably lock on to it. So between August 2015 when first switched on, and February 2017, Boeing aircraft did not fly using RNAV. As a result, the formal review was delayed.
Eventually the CAA set a cutoff at end of September for data-gathering about the track-keeping and the complaints, in order to commence its review.
Complaints from Harpenden, St Albans and Sandridge increased significantly during 2016 and 2017, reporting increased noise disturbance. LADACAN presented evidence at various review meetings including a public meeting in St Albans, that a number of changes had occurred during the same time period. Not only had RNAV caused tracks to move north closer to Harpenden, and had concentrated them between the towns, the number of flights on that route had increased very significantly (currently up 60%) and the mix of planes had become noisier and some altitude reduction had occurred.
However, LADACAN also showed by means of a noise model that the concentration of tracks caused people on either side of the narrow 2km gap between the towns to hear all the flights, whereas previously they may only been aware of around half of them.
On behalf of residents LADACAN submitted a detailed formal report to the CAA review process: click here >> Luton Runway 26 RNAV PIR submission from LADACAN.