One of the most important aspects of the Approach is the need of the aircraft for continuous climb and continuous descent, as air traffic controller you need firstly to respect all the safety parameters, but it's interesting as the airlines are looking forward to have their flights always in the best economically envelope.
Looking closer to the Continuous Descent Arrival (CDA), 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. (EUROCONTROL).
The objective of a CDA is to reduce aircraft noise, fuel burn and emissions by means of a continuous descent, so as to intercept the approach glidepath at an appropriate altitude for the distance to touchdown.
Keeping aircraft as high as possible for as long as possible can be more effective at reducing noise impact on the ground than Low-Power/Low Drag (LP/LD) techniques alone.
CDA vs. non-CDA profile
In a conventional, non-CDA, approach the aircraft descends stepwise, with portions of level flight in-between. By performing a CDA the aircraft remains higher for longer and operates at lower engine thrust. Both of these elements induce a reduction in fuel use, emissions and noise along the descent profile prior to the point at which the aircraft is established on the final approach path.
The ideal CDA starts at the top of descent and ends when the aircraft starts the final approach and follows the glide slope to the runway. Typically CDAs are not possible all the time, not for all arriving flights and not always for the whole descent profile. But at more and more airports measures are taken to use CDA to the extent possible and to gradually increase the percentage of CDA-flights.
In order to facilitate and harmonise implementation of CDA, an ICAO CDA implementation Manual is under development. As an intermediate step, for Europe, CDA guidance material has been published by EUROCONTROL: CDA Implementation Guidance Information.
The Action Plan will ensure the widespread adoption of harmonised CDA in accordance with ICAO and EUROCONTROL guidance:
- To as many airports as possible;
- For as many flights as possible;
- For the longest extent possible for each flight; and,
- Will optimise existing CDA implementations where possible.
- roll-out CDA at up to 100 and more ECAC Airports and to a minimum of 50 airports by the end of 2013; and
- ensure commitment and implementation of the CDA Action Plan and implementation of CDAs at a minimum 20 airports per year.