Review of existing Section 106 Agreement - Thanet District Council

Each aircraft type and subtype has therefore a recognised and formallycertified noise profile, which can be used in establishing noise monitoringprocedure, and in modelling forecast noise in the future from forecast aircraftmovement schedules. For certification purposes the noise measurement usedis the Effective Perceived Noise Level measured in ENPdB which isanalogous to dBA.Chapter 1 aircraft disappeared from the fleets of world airlines in the 1970’sand 80’s, and in the US, Europe and most developed countries Chapter 2aircraft were phased out by 2003, leaving only the much quieter Chapter 3aircraft operating in these countries. In certain parts of the world such asEastern Europe, Africa, South America and China some earlier Chapter 2aircraft are still used. The Annex 16 Chapter criteria represent a range ofaircraft noise, so that the perceived difference between the quietest Chapter 2and the loudest Chapter 3 aircraft can be small. With continuing advances inaircraft engine technology the international bodies are currently in the earlystage of identifying whether, and when, a future Chapter 4 Standard can bepractically introduced.3.4 Noise measurement at airportsThe most commonly used measures of aircraft noise at airports are subdividedbetween :• Single Event Measures associated with a single aircraft movement• Cumulative Measures which seek to represent over time thecumulative effects of many movements over a specified period. Thecalculation of these involves the accumulation of the magnitude ofeach individual noise event due to a takeoff or landing, and the totalnumber of such events in the measurement period. In the UK thedaytime cumulative measure is generally taken over a 16 hour day(07.00 to 23.00 hours) and is expressed as the LAeq(16hour) in dBA.The cumulative measure represents the “average noise level” over theperiod, but in this form cannot differentiate between, say, a single veryintensive and disturbing noise event and numerous moderate noiselevels occurring during the same measurement period.3.5 Airport noise contoursNoise contours are a measure of average noise exposure represented on theground as a series of lines of equal exposure. The cumulative LAeq is usedas a basis for the calculation of noise contours in the vicinity of an airport, andcan be calculated based on schedules and noise readings experienced over adefined period, giving an historical noise contour. Alternatively noise contoursfor future years, based on an airport’s development plans and traffic forecastscan be calculated using a combination of forecast schedules by expectedaircraft type and each individual aircraft noise characteristics from the formalnoise certification process. A number of specialist programs to producecontours are available from noise advisers.In calculating the contour for, say, a particular year it is normal practice tomodel the peak summer period of airport operations, the resulting contour thusEU00142:FINAL REPORT PAGE 10