Night noise at Luton

In contrast with the main airports in the south east of England and a number of major airports in Europe, no controls are imposed on night flying at Luton. Heathrow, for example, has no scheduled departures between 23:30 and 06:00.

The Airport’s voluntary Night Noise Policy comprises only measures which are calculated to prevent a massive worsening of the noise disturbance currently suffered by local residents but which barely affect current operations. In the first six months after the noise thresholds for imposing fines on airlines were lowered (from April 2007), only 1 flight was fined.

The controls on average night noise (23:00 to 07:00) imposed by the 1997 planning permission will not be triggered unless the hourly number of flights at night reaches 80 per cent of the daytime rate, an intolerable situation and, in effect, no limit at all.

The key problem at Luton

The fundamental problem with Luton Airport is that it is located very close to several populated areas. At night, this means that a large number of people experience high levels of aircraft noise which are likely to interrupt or disturb their sleep. Until significant expansion was mooted in 2002, it was probably the case that most people who found that noise levels had become intolerable could move away but the blight of expansion has impacted the property market significantly. However, it remains likely that the population in the immediate vicinity of the Airport is more tolerant of aircraft noise than the norm among the UK population.

Based on laboratory studies, the World Health Organisation (WHO) guidelines suggest that, for good sleep, the number of noise events in excess of 45 dBA L_Amax experienced should not exceed 10-15 per night. The 45 dBA L_Amax indoor level is generally accepted to be equivalent to 60 dBA L_Amax outside.

The DfT and CAA prefer SEL (Sound Exposure Level, sometimes referred to as Single Event Level) as an indicator of sleep interruption with 90 dBA SEL as the threshold. Based on LADACAN’s measurements at about 1 mile from the end of the runway, 90 dBA SEL is roughly equivalent to 84 dBA L_Amax so these criteria appear to be at variance. However, the 90 dBA SEL threshold is based on field studies with people who live in areas subject to high levels of aircraft noise so they are probably not representative of the normal population.

The SERAS study assessed night noise using the population within the 90 dBA SEL contour of the noisiest QC/2-rated aircraft operating at the airport as an indicator. The figure below illustrates this data from SERAS for Luton, Gatwick and Stansted. Despite its short runway which ensures that only quieter twin-engined jets operate, the results for Luton, particularly for westerly departures and easterly arrivals, are generally worse than those for the other airports, principally because of the large population in south Luton which is over-flown. The proposal by NATS to route westerly departures over south Luton will make a bad situation much worse if it is allowed to go ahead.

Note 1: Not surprisingly, the population at Heathrow within the equivalent contours is much greater than at any of the airports shown for easterly departures and westerly arrivals because a large population in west London is overflown. However, as there are no departures from Heathrow between 23:30 and 06:00 and it has two runways which alternate, it is not directly comparable with the single-runway airports.
Note 2: The Western Airspace Extension and associated re-routing of easterly arrivals will not have had any impact upon these figures as the 90 dBA SEL contours do not reach more than 10km beyond the runway ends.

Possible night noise controls

It is self-evident that people are woken at night by loud noises. Controls which deal with the average noise levels rather than the peaks are, therefore, bound to underestimate the real impact on people.

The numbers of people affected at Luton are such that we believe that the Airport should be closed at night. This will be essential if the proposal, published by NATS on 21 February 2008, to re-route westerly departures over south Luton is implemented.

For most people, “night” means a full 8-hour rest period. Although the commercial demands of the low-cost airlines which dominate Luton preclude that civilised aim in the near future, closure between midnight and 06:00 is a reasonable target. LADACAN completed a survey of night disturbance and sleep disruption in 2006. This showed that people are no more sensitive to noise in particular hours of the night than during others. They are simply woken or disturbed when the ‘planes fly.

During the hours when flying is permitted, LADACAN believes that night noise should be controlled by placing restrictions on the noisiest aircraft. As so many more people are exposed to the highest noise levels at Luton than at Gatwick or Stansted, we suggest that, initially, scheduling of aircraft rated QC/2 for noise should be banned at Luton, one category quieter than the aircraft banned at the other airports. This would have affected only 0.1 per cent of movements at Luton during 2005.

Additionally, a nightly quota for scheduled movements by aircraft, initially those rated QC/1, should be established so as to minimise the probability that those living closest to the runway are awoken. The aircraft operated by the main low-cost airlines at Luton are in this category or quieter. This quota could be as low as 10 as most arrivals will shortly be by lower-rated aircraft.

Over time, the thresholds for the scheduling ban and quota would be lowered so as to bear down on noise at night, as required by Government policy, and to approach the WHO limits.

Luton & District Association for the Control of Aircraft Noise - site updated 22 August, 2008