# The Air Navigation (Environmental Standards For Non-Part 21 Aircraft) Order 2008, Paragraph 8: Noise certification reference procedures


(1) The reference procedure must be calculated under the following atmospheric conditions—
(a) sea level atmospheric pressure of 1013.25 hPa;
(b) ambient temperature of 25°C at 1.2m above ground.
(2) The reference flight procedure must comprise a series of level flights overhead the noise measurement position at a height of 150m (492 ft) and at maximum take-off power.

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Source: https://www.legislation.gov.uk/uksi/2008/3133/schedule/paragraph/8 (the official version)
Page: https://openlegislation.uk/air-navigation-environmental-standards-for-non-part-21-aircraft-order-2008/schedule/paragraph-8
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.