RNAV review

RNAV is a GPS-based aircraft navigation system which concentrates flights into a much narrower track than conventional navigation, particularly when turns are involved. This can be a good thing when the narrow track is routed away from people or AOBNs, but if the “motorway in the sky” goes over or close to communities, it concentrates the noise and can make it far worse than having the flights more spread out.

Taking an example from Luton Airport’s first RNAV route, flights between St Albans and Harpenden were previously widely spread but are now much more concentrated – and complaints have risen enormously. Rather than some flights being too distant to hear, people on the fringes of both communities now hear all the flights.

Up until the end of Sep 2017, the Civil Aviation Authority (CAA) collected data ready to review the effectiveness of the first RNAV “GPS-based navigation” implementation at Luton Airport in meeting its design objectives. Data gathering included complaints figures as well as technical information about track-keeping.

The rise in complaints has been dramatic, and as a result the airport operators are looking at ways to alleviate the noise problem. Various options have been discussed:

  • reroute the aircraft – short term we are told this is impossible due to the interlock with flights from Stansted, Heathrow, Northolt and London City
  • switch off RNAV and disperse the tracks again – we are told this is impossible because RNAV has to be adopted on all routes going forwards
  • increase the altitude of the planes – this is being investigated and LADACAN has insisted that possible impacts due to increased throttle earlier on are investigated
  • provide respite routes – whilst theoretically possible, in practice there is little option unless aircraft fly over community A one day and community B the next

If you have been adversely affected by RNAV on the westerly departures route, make a complaint to the airport operators – see our Complaints page.