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Stop Bristol Airport Expansion! (SBAE) is an alliance comprised of the following groups:

cpreBristol Friends of the Earth

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All content © Stop Bristol Airport Expansion, 2009.


100 months

Night Flights

Bristol International Airport has operational hours of 7am to 11pm set by local planning requirements, but in fact its main operations start at 6am. A noise quota counts plane movements between 11:30pm and 6am.

In summer 2008 there were 2320 night flights over 209 days, an average of over 11 per night. Of these 1830 (79%) were arrivals and 491 were departures (21%). Note that this does not count helicopters, small aircraft, or some non-commercial flights. The worst night had 25 flights.

Over the past few years, night flights in the winter season have typically been around 900, making a total of around 3200 per year.
BIA has proposed a new cap on night movements of 4500 per year. This is 40% above the numbers seen in recent years. Most of the growth in night flights has been during the summer months, so it is likely that the 4500 flights would be split 1000 for the winter and 3500 for the summer, representing more than a 50% growth in summer night flights – just when sleep is more difficult and windows are open.

From the 2008 summer data, the times of night of such flights were:

BIA Summer 2008 night flights

bia sumer 2008 night flights

There is no period of the night clear from flights, and the real departure schedule starts at 5am.

It has been argued that these flights are due to charter operators using cheap slots or due to unexpected delays, but in fact 31% were easyJet, 10% were Ryanair, and further flights are likely for the other scheduled carriers, and the same flights arrive at the same late time on a regular basis.

The busiest weeks had 100 night flights, or 14 per night. BIA's plans imply this growing to 150 flights in the worst weeks, or 21 per night, every night.

Noise quota

The only control placed upon night flights is a "noise quota" system. To quote the 2007 monitoring report:

"Night time operations at Bristol International Airport are controlled by a noise quota system. The restrictions specify a night period (23.0007.00) during which time the noisiest types of aircraft may not be scheduled to land or take off. In addition, between 23.30 and 06.00, the night quota period, aircraft movements are restricted by a noise quota limit. Aircraft count against the noise quota according to their quota count (QC) classification.

The quota count itself is related to the noise classification of aircraft as set out in a formal notice published by the CAA on a regular basis. The restrictions allow for dispensations to be given in certain circumstances and there are provisions for dealing with delayed departures and early arrivals. The quota limits are set on a seasonal basis, defined by the period of British Summer Time. The summer season is therefore about seven months long for which a current quota count limit of 1,260 applies. The winter season is about five months long for which a current quota count limit of 900 applies. Up to 10% of the noise quota, if not used in the current season, is carried over to the following season.

Similarly up to 10% of the next season’s quota may be anticipated in the event of an overrun. Any excess overrun is penalised in the following season at double the amount of the excess."

The points allocated depended upon the plane type and whether it is arriving or departing. Many of the flights were allocated 0 points because the planes were just quiet enough to fall below the quota system threshold.

The points vary by the previously measured loudness of the plane type, not the actual flight, and the points halve for every 3dB reduction in measured noise. However, human perception of noise requires a 10dB reduction before the impact is halved.

This means that slight reductions in perceived noise have radically reduced the noise quota points, and that means that if all planes moved from having a quota count of 2 to a quota count of 1, then the number of allowable flights would be doubled.

It is also clear from the description that the quota system is very elastic and does not prescribe any penalty for violation of the quota total. It also appears that no routine and active monitoring of the quota has been undertaken by the local authorities, and none of the data is independently verifiable.

BIA exceeded the quota count for the summer in 2004 when 2082 flights occurred, but as they were under the limit in winter there was no violation of the quota system. In 2008, when 11% more flights occurred, the "quota count" was 14% lower than in 2004.

Even though some individual noisy aircraft were eliminated over that period, it is clear that many individuals would be more affected by the higher number of flights and this is not reflected by the quota count.

It is obvious that the quota count has no restraining effect upon the airport's operation, and the proposed cap is in fact a license to increase summer night flights by 50%.