Aircraft Noise (Landing Procedures) 26. Sir Anthony Royle asked the Secretary of State for Trade when the high-speed low-drag descent quieter landing system will be made permanent in view of its success in reducing landing noise over the Richmond constituency. Mr. Clinton Davis The continuous descent and low-power/low-drag approach procedures were promulgated as the standard method of approach at Heathrow on 31st March 1978. An assessment of the noise benefits was made during the preceeding trials by the Civil Aviation Authority and a copy of its report has been placed in the Library.