The Mayor's Ambient Noise Strategy - Greater London Authority

The Mayor’s Ambient Noise Strategy Mayor of London 123
There is a wide variation in individual response to aircraft noise. The noise
index on which the 57 L Aeq
contour is based was derived at a time when the
number of aircraft movements was much lower than today 11 . A three year
study was announced by the Aviation Minister on 8 May 2001 12 . The study
is expected to cover the relationship between noise levels and annoyance,
attitudes to sleep disturbance at night, and values placed on lower noise
levels relative to other environmental factors. It is important that research
encompasses the difficulties people have getting to sleep or getting back to
sleep once woken, as well as actually being woken once asleep. It is unlikely
that a single noise index will be suitable for all policy purposes.
Requirements of the Environmental Noise Directive 2002/49/EC include
use of the L den
and L night
indicators (see glossary) averaged over the whole
year. Other indices may be used on a supplementary basis. Night noise
contours have not previously been produced as a standard practice for
Heathrow. L night
contours are likely to provide useful addition information.
Other information, such as number of events along the glidepaths, at
different times, is also likely to be needed (see ‘Public information and
communication’ below). Changes in the way noise is quantified do not, of
course, reduce it. However, ensuring that any noise index reflects adverse
effects on people as accurately as possible must be an essential part of
good decision making.
4C.10 Noise from jet aircraft engines was significantly reduced with the
introduction of high-bypass turbofan designs. The need for noise
reduction around airports is expected to influence aircraft design further,
although there can be tensions with other environmental objectives, such
as minimising fuel use. Civil aircraft are required to hold a noise certificate
containing noise values related to certain test conditions. Noise standards
for aircraft are agreed internationally through the International Civil
Aviation Organisation (ICAO). 13 Some older low by-pass engined aircraft,
fitted with ‘hushkits’ to enable them to meet ‘Chapter 3’ standards (see
glossary) remain, but are a small minority of the fleet. 14 At Heathrow,
nearly all movements are by Chapter 3 aircraft.
4C.11 After the 2002 Chapter 2 phase-out, there is no immediate prospect of a
technological advance giving a similar reduction to that achieved through
introduction of high by-pass engines. 15 The 2001 ICAO decision on a new
Chapter 4 aircraft noise standard did not secure the degree of
improvement many had pressed for. European negotiators seeking quieter
aircraft at ICAO were outvoted by those from other parts of the world
whose priority was cheaper aircraft. The ICAO decision effectively pushes
the onus onto regulators, airport operators and land use planners in
countries where noise sensitive airports are located.