Review of the Departure Noise Limits at Heathrow, Gatwick and Stansted Airports: Effects of Take-off Weight and Operating Procedure on Noise Displacement

This Study illustrates the nature and practical incidence of 'far-out noise displacement', a name given to the effect in which the cutting back of engine thrust to reduce noise close to an airport can increase noise further away. Although this effect is well known - e.g. ICAO specifies alternative operating procedures for reducing noise at different distances from the airport - it should not be a significant consequence of the proposed new noise limits. This is because a major influence upon departure noise at present is the common airline practice of minimising take-off thrust. If aircraft use more power to gain height as quickly as possible, which the proposed limits should encourage, there will be very little 'far-out displacement' relative to the noise of current operations.