Continuous descent approach (CDA), also known asoptimized profile descent (OPD), is a method by which aircraftapproach airports prior to landing. It is designed to reduce fuel consumption and noise compared to other conventional descents. Instead of approaching an airport in a stairstep fashion, throttling down, and requesting permission to descend to each new (lower) altitude, CDA allows for a smooth, constant-angle descent to landing.

A continuous descent approach starts from the top of descent, i.e., at cruise altitude, and allows the aircraft to fly its individual optimal vertical profile down to runway threshold. Some airports apply constraints to this individual optimal profile.

The approach toLondon Heathrow Airport uses CDA, particularly at night, to minimizenoise pollution.^[1] It is also used atGatwick Airport.^[2]

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