How noisy will it be?

• NATS tell us we can expect up to 60 db from a Boeing flying between 6000 & 7000ft.
• Below 6000ft we can expect up to 67 db

The Government claims that "the onset of significant community annoyance" starts when the noise from aircraft averages out at 57 decibels, known as 57dB(A) LAeq. The World Health Organisation (WHO) puts the figure between 50 and 55 decibels (and about 10 decibels lower at night). On this basis, it recommends maximum noise exposure levels of 55 dBA LAeq to avoid the risk of people being significantly annoyed.

So the tables in the consultation papers that suggest aircraft above 6000ft will have Lmax (LAeq) of less than 55-60dBA masks the fact that the new hold stacks will be over peaceful rural communities and will be around the WHO figure of 55dBA LAeq.

The consultation document states in section E 2.25 “Aircraft in the new holds will not fly at heights below 7000ft, although aircraft leaving the hold may start their descent to the airport before leaving the holding area and therefore be at levels below 7000ft beneath the holding area. The frequency or heights are not discussed for these manoeuvres.”

Perhaps even more worrying section E 3.5 states “When holding is not required, aircraft may follow a descent path that takes them on a direct route beneath parts of the hold. Therefore, the lowest height for aircraft in the hold is not necessarily the lowest height that aircraft may be seen in the geographical location of the hold.” In other words aircraft could be flying at any height within the hold stack.

The consultation documents also state that the NATS proposals would have a ‘negligible’ impact on local air quality, while a balance has been sought in terms of minimising both noise disturbance and carbon emissions (which can increase slightly if longer routes are taken to avoid overflying densely populated areas). “Improvements in fuel efficiency and minimising the number of people over flown below 7000ft were given greater priority than avoiding over flight of AONBs and National Parks.” The consultation gives little indication of possible effects on tranquillity, citing the absence of universally accepted metrics for measuring these impacts.