How the Disruption Index is calculated

The disruption index is a weighted lead indicator that represents the expected level of disruption caused by aircraft traffic at a specified location.

An aircraft flight event is considered as being disruptive if it’s unexpectedly loud, regular i.e. occurs more than twice per hour, and occurs at unsociable times. e.g. on a Saturday, Sunday or between the hours of 8.00pm and 6.00am. The scale of disruption is further weighted by the flight’s altitude i.e. under 8000 feet, and direction i.e. Departure and also the volume of flights within a single an hour.

There are six indicator bands as shown in the table below.

NoneThere are no regular disruptions. In this case the Disruption Index measure is not included in our Scorecard.
MinimalThere are regular disruptions but they are relatively insignificant. Expect less than 2 disruptions a day.
LowThere are regular disruptions but at a relatively low level. Expect less than 5 disruptions a day.
FrequentThere are frequent disruptions. Expect between 5-10 disruptions a day.
HighThere are frequent disruptions. Expect between 10-30 disruptions a day.
Very HighThere are frequent disruptions. Expect between 30-50 disruptions a day.

Aircraft disturbance is subjective and its effect can be impacted by other background sounds such as road noise.

Also it depends on your own life-style in that those working from home or retired tend to be more sensitive to aircraft disturbances that occur throughout the day. These scenarios are also be supported by our Aircraft Traffic Survey.

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