It is recognised that Member States have decided on noise-related operating restrictions in accordance with national legislation based on nationally acknowledged noise methods, which, as yet, might not be fully consistent with the method described in the authoritative European Civil Aviation Conference Report Doc 29 entitled ‘Standard Method of Computing Noise Contours around Civil Airports’ (ECAC Doc 29) nor use the internationally recognised aircraft noise performance information.

Competent authorities will ensure the use of noise assessment methods which have been developed in accordance with the European Civil Aviation Conference Report Doc 29 entitled ‘Standard Method of Computing Noise Contours around Civil Airports’, 3rd Edition.

While the use of approved breathalyzer tests is a method of measuring the level of blood alcohol and has withstood numerous legal challenges, and the relationship between blood alcohol levels and impairment is well established, there is no generally accepted objective method of assessing drug impairment, nor is there a consistent established correlation between concentration of a drug detected in one's system and impairment (1015) [Translation] A 2003 Department of Justice consultation document recognized the serious limitations of drug tests:

The 55 and 65 dB contours must also be shown on one or more maps that give information on the location of villages, towns and agglomerations within those contours.

1.7. In case of graphical presentation, strategic maps must at least show the 60, 65, 70 and 75 dB contours.

The demographics issue that I am aware of is this: there is a deep dip in the experience level from the apprentice up to about 15 years of service.