§ Mr. John Leeasked the President of the Board of Trade what has been the increase in noise as measured in decibels at maximum and minimum times of activity at London Airport over the period 1959 to 1969.
§ Mr. William RodgersWith the rapid growth of jet traffic the average noisiness of the aircraft using Heathrow has increased by some 5 perceived noise decibels since 1959 when taking off and some 139W 6 PNdB when landing. At busy periods the number of aircraft is about twice what it was in 1959, which increases the disturbance in terms of the Noise and Number Index by some 4.5 NNI. The overall effect is thus an increase in average disturbance of some 10 NNI. We do not collect data for periods of minimum activity.