Continuous Descent Operations
The term Continuous Descent Operations describes a procedure whereby the aircraft glides smoothly down to the airport without leveling off – meaning there is no interruption by the pilot during the descent. The benefits are financial and environmental because less fuel is used, aircraft gas emissions are lower and there is less noise. In the absence of a standardised definition, FABEC has taken the initiative in its first common FABEC Performance Plan to establish CDO procedures at about 25 major airports within the FABEC area.
There are various reasons why the execution of these procedures does not always materialise in practice. First of all, it depends on how congested the airspace is – there may be conflicting overflights or a high concentration of inbound flights. Second, the pilot/airline have to accept the manoeuvre, and this can depend on aspects such as aircraft prioritisation, available parking spaces on the ground, and crew skills.
Experts distinguish between two kinds of CDO approaches. The so-called Fuel CDO starts from top of descent to 1800 feet above ground level. Every fifth aircraft landing within FABEC is using this procedure. Almost double this number use the so-called Noise CDO which starts at the lower altitude of Flight level 75/105.