Each runway in use at an airport has its own set of flight paths, and each flight path will affect different areas. As the runway in use changes, the flight paths in use will change, and so too do the suburbs affected by aircraft movements.

The runway in use at any given time and the direction of the traffic flow will vary primarily according to the wind conditions at the airport. This is because aircraft must take off and land into the wind for safety reasons. Generally, this means that in:

• Northerly wind conditions at the airport (including north-westerlies and north-easterlies), north flow will be used.
• Southerly wind conditions at the airport, including south-westerly and south-easterly conditions, south flow will be used.

However at times a runway direction may be used with a small amount of tailwind as long as it does not exceed the Civil Aviation Safety Authority’s limits for downwind (tailwind) and crosswind.

When the wind at the airport is calm or light, other factors are taken into account in selecting the runway that will be used. For example, the location of the terminals and the positioning of the taxiways can influence the decision.

At Sydney Airport, the proximity of the terminals to the northern end of the westernmost parallel runway means that in busy periods when south flow is being used, there is not always enough space on the taxiways between the terminals and the runway end for all the waiting aircraft to queue for take-off.

To manage this, some aircraft may need to be held at the departure gate until space becomes available. This can result in delays and create knock-on effects around the country. For this reason, if the wind is not a factor in the decision, north flow will usually be preferred over south flow during peak periods.

The proximity of the terminals to the runway at northern end of Sydney Airport means there is limited space on the taxiways for queuing. Below right: There is much more room for queuing aircraft on the taxiways at the southern end of the Airport.

Our page on Runway Selection discusses how decisions are made about which runway to use.

There is a flight path for aircraft arriving into Sydney from northern ports that brings aircraft through the Sydney heads and southwards down the coast, over water, to arrive on the easternmost parallel runway. This flight path is used when the parallel runways are being used in a northerly direction (“north flow”).

There are times when air traffic controllers need to take aircraft off this flight path to ensure they remain safely separated from other traffic and/or can be efficiently sequenced with aircraft arriving from the east, south and west for landing. When there is poor weather, or in peak periods when there is a high volume of traffic in the airspace, this is more likely to occur.

The image at right shows actual tracks of aircraft arriving into Sydney from the north and travelling southwards to land on the easternmost parallel runway.

When aircraft are diverted from the usual flight path they must be directed over land, and will pass over suburbs such as Rose Bay, Dover Heights and Point Piper. It is not possible to divert these aircraft further east, over the water, because this would create potential conflicts with aircraft that are departing from the easternmost parallel runway and heading north-east. The conflicts could occur because the departures and the arrivals would be at similar altitudes when their paths crossed.

The image below is a zoomed in view of the tracks of aircraft arriving from the north. Aircraft on the usual flight path can be seen flying through the heads and down the coast over water. Aircraft that have been taken off the normal flight path can be seen flying over land.

Aircraft taken off the usual flight path will generally be in the altitude range of 6,000 to 8,000 feet as they pass over the eastern suburbs. This is around twice as high as the jet aircraft that depart over the area.

Air traffic controllers are aware of potential noise implications for the community and do not take aircraft off standard routes unless it is operationally necessary. Unfortunately, when operationally required, this cannot be avoided.

Sydney Airport has three runways:

• Two parallel runways that are orientated north/south, and
• A single crossing runway that runs east/west.

Runways can be used in both directions which results in four flows that are outlined in the illustration below. To learn how the flow direction is determined, visit our When is each flight path used? page.

The animation is indicative only and provided for information purposes, on occasions flights may leave these general areas from time-to-time.