§ Sir T. Low
asked the Minister of Supply what measures he is taking to keep down the disturbance caused by aircraft, ordered by him, flying at supersonic speeds over the Blackpool area.
§ Mr. Aubrey Jones
Supersonic flights are essential to the Ministry of Supply's development work for the defence programme, but I realise that they can cause some disturbance. I have taken special measures to minimise this, as described in the reply to the hon. Member for Maidstone (Sir A. Bossom), on 11th July, 1955—(OFFICIAL REPORT, cols. 1577–8). These provide that supersonic flights shall, whenever possible, take place over the sea. If they must be made over land, they are carried out above 30,000 feet, except in very rare cases. These exceptional cases are authorised individually, with a minimum height for the boom, and only over sparsely populated areas. These instructions are strictly observed, and are not relaxed even for bad weather.
Supersonic booms heard in the Blackpool area are caused mostly by the Ministry's Lightning aircraft which have to be tested from Warton airfield. The supersonic flights normally take place over the Irish Sea, but at the great speeds at which this aircraft is now flying, it is very difficult to carry out useful tests without sometimes approaching the mainland or the Isle of Man. The aircraft are normally directed by the Royal Air Force radar surveillance.
Supersonic booms may be heard over a wide area, which may extend to as much as 15 miles on either side of the aircraft track. But damage is rare, and usually 149W of a minor nature. This was shown by the results of an investigation made by the Building Research Station of the Department of Scientific and Industrial Research which were given in reply to the hon. Member for Lincoln (Mr. de Freitas) on 20th November, 1957— (OFFICIAL REPORT, cols. 42–43).
The restrictions on supersonic flying add to the difficulties of the Ministry of Supply development programme, but in order to minimise the disturbance to the public in the Irish Sea coastal areas, I shall continue to require that most of these flights are carried out over the sea and shall allow flying over land only when it is essential.