The Christchurch Flight Paths Trial

The purpose of the trial is to gather data to inform the implementation at Christchurch over the coming years. The trial will allow for the review and refinement of PBN flight paths prior to formal adoption, so the environmental, safety, community noise and aviation network efficiency benefits of the new methods are optimised.

The PBN approach paths selected for the first phase of the trial are the product of significant consultation between Airways New Zealand, Board of Airline Representatives New Zealand (BARNZ), Christchurch Airport and New Southern Sky representatives.  The approach taken by the trial partners in selecting these particular flight paths for trial was to achieve a balance between the technical and operational needs of aircraft operators, and the desire to mitigate the noise effects on communities.

Aircraft must land into the wind, so use of the PBN trial arrival flight paths will vary during the trial and will be made considering factors including the direction of the wind and safe separation distances between aircraft.

Aircraft approach the airport from various locations, and before landing on the runway, must line up with the extended centreline of the runway, to stabilise the aircraft for landing.  This lining up typically occurs at a range of distances between about 3-12 nautical miles from the airport, but PBN allows instrument guided traffic to get much closer to the airport before lining up for the final approach.   PBN approach paths have been developed for aircraft landing on the main runway from the south and the north, and also for the cross-wind runway for aircraft approaching from the north-west.

At the moment, aircraft arriving at Christchurch Airport approach the airport in one of two ways.  On fine days, aircraft approach the airport on what is called a “visual approach”, where pilots guide the aircraft into the airport manually, which results in aircraft being spread over a wide area on approach.  On days where there is poor visibility, aircraft are guided into the airport by instruments, and approach the airport by joining the extended centreline of the runway at either 8 or 12 nautical miles away from the airport.  This means aircraft flight tracks are more concentrated, but not very efficient as extra fuel is burned to line up so far away from the airport.  On the cross-wind runway, there are no instrument approaches at all, so without PBN approaches, the runway cannot be used in poor visibility.

The PBN approach paths into Christchurch provide a set of flight paths which can be flown on both fine and poor visibility days, and allow aircraft to line up with the runway much closer to the airport.

The portion of air traffic expected to fly the trial approach paths will vary, but Airways’ indications are that about a quarter of scheduled passenger arrivals will use them on a “typical” day.

Airways’ figures show that, when in use, Runway 02 (primarily used in easterly wind conditions) can expect approximately 28 PBN flights a day, which is 30% of all flights.

Runway 20 (primarily used in southerly wind conditions) can expect approximately seven flights a day (8%). Runway 29 (primarily used in north-westerly conditions) can expect approximately 28 flights a day (30%).

 

 

Those numbers on the runways may vary on a day where the wind changes direction, but the maximum number of PBN flights per runway should not rise.

Most jet aircraft, as well as some turboprop aircraft (from mid-2018), will be capable of flying the trial approaches.  However many will still fly a visual approach in fine weather (including north-westerly conditions using Runway 29), or may fly another approach type for training, or to assist with Air Traffic Control sequencing.

The impact of the trial paths, in general terms, is that aircraft will be at a higher altitude over the city, which will result in reduced noise. There will also be fewer flights over Wigram, Hornby and Prebbleton and the trial flight paths will avoid direct overflight of Templeton and West Melton.