RNAV implementation

RNAV stands for Area Navigation, and is a system for aircraft navigation based on using software-assistance to navigate flights using a network of beacons to follow a designated route. It is potentially more accurate than conventional navigation, which means that aircraft stick more closely to a defined “centre line”, rather than being more dispersed.

If you live more than a mile or two from the centre-line of a route, you may consider that it’s probably better to have flights very tightly constrained rather than them sometimes passing more closely than usual due to being more scattered. But if you happen to live underneath the centre line of an RNAV route, all the flights will pass overhead.

Luton Airport is using RNAV on a departure route which heads out to the west, turns left to pass between Markyate and Flamstead, then left again after crossing the A5 to track between Hemel / St Albans to the south, and Redbourn / Harpenden to the north.

The majority of flights on that route are now using the new system, though some aircraft types are not following the route correctly, some airlines do not appear to fly it correctly, and business jets are often less accurate than commercial flights.

Alongside the introduction of RNAV, air traffic controllers have been asked not to steer aircraft off the centre line aircraft below 4000ft or before they cross the railway line between Harpenden and St Albans. This change reduces the “corner-cutting” which had plagued villages such as Flamstead and Redbourn, and affected South Harpenden. Flights which depart significantly from the prescribed route are also now being fined.

The RNAV system is not delivering the hoped-for accuracy in high winds, and is due to be modified around end 2016 by overlaying a potentially more accurate system called RNP. This should help to keep the aircraft better on track during the earlier part of the route.

Residents who wish to comment about the effect of this route on their noise experience when the wind is from the west (ie when this route is used) should email noise@ltn.aero

As background, the detailed Airport consultation document can be uploaded by clicking here: RNAV1 Consultation Document, and the noise results by clicking here: Appendix C. Detailed Noise Monitoring Results

LADACAN’s response to the RNAV consultation can be downloaded by clicking here: LADACAN Response to RNAV1 consultation.