Aircraft Lmax data

This page provides representative Lmax data as a function of aircraft height above ground, together with information on how the data have been generated and its uncertainty.

Calculation Process

Data is derived from the UK civil Aircraft Noise Contour model, “ANCON” version 2. This has been used since 1995 to calculate noise contours at the designated London airports.

Every summer the ANCON model is validated with hundreds of thousands of measurements obtained from around Heathrow, Gatwick and Stansted airports. The calculation process requires that noise levels are generated for locations beneath an aircraft flight track.

Since each type of aircraft reaches a certain height at different distances after take-off (and likewise before landing prior to intercepting the standard 3° glide path), The CAA Environmental Research & Consultancy Department (ERCD) identified the unique distance from start-of-take-off roll and to touchdown, for each ANCON aircraft type category at 500ft intervals.

These locations were then used to determine the corresponding mean Lmax levels for departure and arrival operations for each ANCON type. Tables 2 & 3 below provide combined tables of representative Lmax levels.

Aircraft groupings

In order to simplify the data, it has been grouped in logical categories of aircraft size. Data has then been linearly averaged across different specific types and across the airports to provide an overall average Lmax value for each altitude and operating mode. The specific groupings chosen are listed in Table 1.

Using the groupings listed in Table 1, Tables 2 and 3 below provide representative Lmax data for arrivals and departures respectively.