CDA

[patm92]

Hi All

What is the official definition of a CDA? I've heard two different views;
- As long you one doesn't level off, provided your RoD is 300' per minute or greater.
- A rate of descent of 300' per minute or greater, but you can level off but not for a greater distance than 2 miles.

What altitude/ Flight Level does a CDA actually start?

Thanks

[DaveReidUK]

ICAO defines CDO (Continuous Descent Operations) as:

"An aircraft operating technique aided by appropriate airspace and procedure design and appropriate ATC clearances enabling the execution of a flight profile optimized to the operating capability of the aircraft, with low engine thrust settings and, where possible, a low drag configuration, thereby reducing fuel burn and emissions during descent. The optimum vertical profile takes the form of a continuously descending path, with a minimum of level flight segments only as needed to decelerate and configure the aircraft or to establish on a landing guidance system (e.g. ILS)"

The European definition of CDA (Continuous Descent Approach) is:

"An aircraft operating technique in which an arriving aircraft descends from an optimal position with minimum thrust and avoids level flight to the extent permitted by the safe operation of the aircraft and compliance with published procedures and ATC instructions."

What altitude/ Flight Level does a CDA actually start?I've heard two different views;
- As long you one doesn't level off, provided your RoD is 300' per minute or greater.
- A rate of descent of 300' per minute or greater, but you can level off but not for a greater distance than 2 miles.Both definitions imply that a CDA can start at any point from TOD onwards, but neither specifies any maximum duration for intervals of level flight during the course of a CDA.

However NATS classify an arrival as a CDA if it contains, at or below an altitude of 6000ft

no level flight; or

one phase of level flight not longer than 2.5nm