§ Mr. Adleyasked the Secretary of State for Trade (1) if, pursuant to his answer on Concorde noise measurements on 13th October, when he stated that the figures in his answer were quoted in a unit of measurement, namely PNDB, not commonly used internationally for measurement and comparison of aircraft noise, he will now quote the figures in the internationally-used units of EPNDB, in order that comparisons with other aircraft can be made;
(2) if, pursuant to his answer on Concorde noise on 13th October, he will now give the comparable figures for noise, under similar conditions, in the unit commonly used internationally for measurement and comparison of aircraft noise, of Concorde, DC8-50 and Boeing 707/320C; and how many aircraft movements of each of these three types of aircraft he expects at Heathrow weekly in 1976.
§ Mr. Clinton DavisNoise measurements are normally made in perceived noise decibels (PNdB) at Heathrow and at many other airports. The results of476W this summer's Concorde endurance trials are not available in effective perceived noise decibels (EPNdB) and this information could only be obtained at disproportionate cost. However, I would refer the hon. Member to the reply given on 28th October—[Vol. 898, c. 417–18]—to the hon. Member for Thornaby (Mr. Wrigglesworth) by my right hon. Friend the Secretary of State for Industry announcing the results of the Casablanca trials in EPNdB and giving comparative data for the Boeing 707 and DC8. When Concorde comes into commercial service at Heathrow it will not initially exceed four movements a week. The number of 707 and DC8 movements is not expected to be significantly different from those in 1975, about 550 and 200 per week respectively.
§ Mr. Adleyasked the Secretary of State for Trade if, pursuant to his Answer on Concorde noise measurements on 13th October, when he gave the maximum take-off and landing readings at various mobile points, on given dates, he will now give the minimum noise measurements, at the same measurement points, on the same dates, in order that both maximum and minimum measurements may be compared, and an assessment made of the noise measurements of the aircraft.
§ Mr. Clinton DavisThe recorded noise of an aircraft rises from zero to a peak and falls back to zero as the aircraft passes a monitoring point. The figures quoted were the maximum levels recorded at the particular monitoring points.