Air Traffic Control is in constant contact with all aircraft, and they define their route and heights. The Standard Instrument Departure (SID) routes in use at this time are not precision routes and as such there is wide dispersal in the routes that aircraft will fly. The current ground based technology directs aircraft to ‘waypoints’ along the route. Noise Preferential Routes were introduced on the SID routes by the airport to minimise disturbance on local communities. The Noise Preferential Routes end at 3,000ft (4,000ft on the GRICE SID from Runway 24). The current SIDs extend 1.5km from the centre line of the route

Occasionally aircraft may be diverted off the normal flight path for weather avoidance. A flight will request from ATC a deviation from flight path for weather avoidance. ATC agree to the captain’s requested course whenever possible, as it is the captain's responsibility to ensure the safety of the aircraft and ATC have no recourse to that decision making.