§ 20. Mr. Jessel
asked the Secretary of State for Trade and Industry how much weighting is given to flight frequencies, and to the peak amount of noise in any one flight, respectively, in compiling the Noise and Number index.
§ The Under-Secretary of State for Trade and Industry (Mr. Cranley Onslow)
The weightings in the formula are based on the findings of the Final Report of the Wilson Committee on the Problem of noise published in July 1963 (Cmnd. 2056). The NNI scale was re-examined by the Research Sub-Committee of the Noise Advisory Council in 1972. That committee did not recommend any modification of the formula, which we still consider the best available measure of annoyance caused by aircraft noise.
§ Mr. Jessel
Would not my hon. Friend agree that this index gives a greater weight to changes in the volume of peak noise for any given place than to the number of aircraft passing by? Would he not also agree that the sheer number of flights, which at Heathrow now amounts to about 600 per day, is becoming increasingly annoying? Ought not the index to he modified now to reflect all this?
§ Mr. Onslow
I recognise that many people regard frequency as the major irritant but I hope my hon. Friend will accept that, if we were to revise the 1125 system, we should have to have some thorough resurveying of the situation. Statistics apart, the real point is that there are a great many residents near Heathrow and Gatwick who have been encouraged to expect relief from aircraft noise with the construction of the third airport and much of their tolerance of noise has therefore diminished. This is therefore a powerful reason for going ahead with the Government's intentions.
§ Mr. Bishop
Concern about the frequency of aircraft is an important aspect of noise considerations, and the infrequency of supersonic flights is a possible answer to critics of Concorde and that method of flying. This question arises, as do many others, from the concern about lack of Government involvement in research and development on noise. Will the Minister therefore do more to encourage manufacturers to produce quieter engines as a way out of the dilemma?
§ Mr. Onslow
I am not sure that I follow all the tortuous derivations of the hon. Member's question, but if the manufacturers think there is a commercial market for noise suppression kits perhaps they might set the pace in producing them.