In accordance with (ICAO) DOC 8168 - OPS, noise preferential routes are established to ensure that departing and arriving aeroplanes avoid over flying noise-sensitive areas in the vicinity of the aerodrome as far as practicable. In establishing noise preferential routes:
turns during take-off and climb should not be required unless the bank angle for turns is limited to 20° (climbing at V2 + 10 to 20 Kt).
turns during take-off and climb should not be required unless the aeroplane has reached and can maintain throughout the turn a height of no less than 100 m above terrain and the highest obstacle.
no turns should be required coincident with a reduction of power associated with a noise abatement procedure.
turns during take-off and climb should not be required unless the bank angle for turns is limited to 28° (climbing at V2 + 10 to 20 Kt).