In Brisbane, the noise abatement procedures set out that “Reciprocal Runway Operations” is the preferred runway scheme, particularly between 10.00 pm and 6.00 am. When reciprocal operations are in place, all aircraft arrive and depart over Moreton Bay. This is unusual, because generally runways are used in one direction only at any given time, that is, all aircraft land at one end of the runway and take off from the other end. Because reciprocal runway operations require aircraft to take off from the same end that other aircraft are landing to, increased separation between arriving and departing aircraft is required to safely implement this configuration. Therefore reciprocal operations can only occur when the traffic levels are low. If reciprocal operations were used when traffic levels were high it would result in long delays and holding.Another constraint on the use of reciprocal operations is the weather. If the wind conditions are not suitable, and/or if there are thunderstorms in the area or low visibility, reciprocal operations cannot be used.