Continuous climb and descent operations

Towards a flexible, optimum flight path that delivers major environmental and economic benefits.

Status of Task Force work flows following TF#8 meeting (March 2020)

The 8th meeting of the European CCO / CDO TF took place at EUROCONTROL HQ on the 4-5th March 2020. A short summary of the status of ongoing work / outputs of the TF following TF#8 are detailed below.

European CCO / CDO Action Plan (AP) – Since TF#7, detailed CDO AP reviews plus additional comments were received from Wizz Air, NATS, LHR, SJU, EUROCONTROL (NAV, PRU, Research), skeyes, IATA, Novair, DLH, DFS, Skyguide, Brussels Airlines, ENAV, Storkjet, Ryanair, Finavia, Airbus, Enaire and LFV. The process for the Action Plan delivery will be as follows:

  1. Draft AP to be delivered for approval to RNDSG/100 (28-29/4); and,
  2. Any comments will be addressed and an updated draft delivered to NETOPS/27 (13-14/5).

The Action Plan may be released subject to approval of NETOPS although the Action Plan will then continue its way through NDOP (Network Directors of Operations) and NMB – into the NM machinery, which means that it can be updated in the future.

Updates to the Action Plan since TF#7 include green summary boxes to highlight the key messages of each appendix, additional case studies, additional future developments and the highlighting of case studies in the appendices. Next steps will be to add additional content to appendix H on CDO facilitation and address the remaining comments received.

Key messages of the Action Plan - In an update on previous AP iterations, the TF has identified several messages that should be passed in the AP which include some that may be inconsistent with current operations. The Action Plan will not make any recommendations to take these messages into account but will pass the message in order to fuel discussion in the future. The AP will include the following messages:

  • Arrivals should be kept above departures wherever possible;
  • For an individual aircraft, a level-off in the climb may save more fuel than the same distance level-off in the descent;
  • For departures, a track extension should mostly be avoided as all track extensions result in the track extension being flown with fuel burn at the cruising level fuel burn rate; and,
  • If there is a choice between a track extension to facilitate CCO or a level-off without a track extension for a departure, a level-off may save more fuel than the CCO.

The TF plans an Autumn workshop to further discuss these messages with Stakeholders. We have also shared the information through the ICCAIA organisation to ensure dialogue with, and feedback from, the major manufacturers on these messages.

ATCO refresher training – The ATCO refresher training is pretty much completed with a draft circulating for comment with ATCO members of the TF. Initial feedback is very positive. Additional content on the correct messages to give for phraseology and final quiz questions remain to be added. Provided there are no major issues identified in the review, the ATCO refresher training material on aircraft energy management will be available by June.

Aircraft Operator training material – The TF will develop a Computer-Based Training (CBT) on CCO / CDO and / or associated visual aids to support Aircraft Operator refresher training materials. The focus of this CBT should be on ‘awareness’ as opposed to ‘training’ and should promote general good practices without impinging on any airline SOPs.

CCO / CDO Performance tables – A first draft of the performance tables, to measure CCO / CDO performance for all airports in Europe and all airlines that fly in Europe, has been created. Following the next iteration (a couple of weeks), a draft will be shared with the TF for comments.

Harmonised AIP material – The proposal for harmonised AIP material: (location, structure and content) has now passed through the EUROCONTROL Working Arrangements with positive approval. The TF has been approached by one European ANSP to help them develop their CDO-related AIP material in line with the harmonised AIP material proposal. This support should also enable the development of a case study.

Communications – In order to support the roll-out of the Action Plan, the TF has developed a one-page, two-sided glossy handout to publicise the Action Plan – a draft has been circulated with TF members for comments.

CCO / CDO TF meeting #9The next proposed TF meeting is planned to take place on the 23/24th June (Tuesday / Wednesday) at EUROCONTROL – should a face to face meeting not be possible, we will distribute a new proposal in the coming weeks.

NEW - the European CCO / CDO TF has also, not only supported the joint initiative between IATA and CANSO (in collaboration with A4E, ERA, AIRE, NM and IFATCA) to reinforce the principles to facilitate and encourage CDO/CCO and more direct routings while traffic volumes are low due to the COVID-19 crisis, but also coordinated the development of a set of actions for key stakeholders to support this initiative, which have now been shared by CANSO at the global level.

Continuous Climb and Descent Operations (CCOs and CDOs) are aircraft operating techniques enabled by airspace design, instrument procedure design and facilitated by air traffic control (ATC). CCO and CDO allow aircraft to follow a flexible, optimum flight path that delivers major environmental and economic benefits - reduced fuel burn, gaseous emissions, noise and fuel costs - without any adverse effect on safety.

CCO and CDO operations allow arriving or departing aircraft to descend or climb continuously, to the greatest extent possible. Aircraft applying CCO employ optimum climb engine thrust and climb speeds until reaching their cruising levels. With CDO, aircraft employ minimum engine thrust, ideally from top of descent and in a low drag configuration, prior to the final approach fix. Employment of these techniques reduces intermediate level-offs and results in time being spent at more fuel-efficient higher cruising levels, hence significantly reducing fuel burn and lowering emissions and fuel costs (see ICAO Doc 9993 and ICAO Doc 9931).

340,000 tons

fuel savings (1 million+ tonnes CO2)

+ € 150 M.


1-5 dB

noise reduction

Implementation support

We, at EUROCONTROL, support CCO and CDO deployment. A dedicated team works with stakeholders (ANSPs, aircraft manufacturers and aviation industry associations such as IATA, A4E, AIRE, EBAA, ERA, ACI and CANSO) to measure and maximise the benefits achievable in the current ATM framework. The team also supports the facilitation of a more advanced CCO and CDO concept that will result from deploying future ATM tools and procedures. A guide to implementing continuous descent is available. 


Deployment of optimised CCO and CDO throughout Europe will be beneficial to all European ATM system stakeholders and will help the network to address the environmental challenges it faces.

In 2018, EUROCONTROL conducted an ECAC-wide CCO and CDO analysis using 2017 traffic data, in order to estimate the potential network benefits of optimising the CCO and CDO in terms of fuel savings, emissions reduction and fuel costs.

 For CCO, the study concluded that 94% of flights in ECAC currently fly CCO to FL (Flight Level) 100 while 74% fly a full CCO to Top of Climb (ToC).

 For those flights currently flying non-CCO profiles, the average time in level flight to the ToC was 168 seconds with per-flight savings estimated at 15kg fuel/48kg CO2/7EUR. Across the network, this would result in a potential average per-departure saving of 4.3kg fuel/13.7kg CO2/~2€

 For CDO, the study concluded that 41% of flights fly CDO from FL75 (the top of the noise CDO) while only 24% fly a CDO from Top of Descent (ToD – the top of the fuel CDO). 

For those flights currently flying non-CDO profiles, the average time in level flight from the ToD was 217 seconds, with per-flight savings estimated at 46kg fuel/145kg CO2/20EUR. Across the network, this would result in a potential average per-arrival saving of 35kg fuel/110kg CO2/15€.

 The ECAC-wide study identified two main conclusions:

  • The results indicate that in Europe the potential savings from optimising CCO and CDO are up to 340,000 tonnes fuel/year, (1.1M tonnes CO2/150M EUR) *; 
  • The potential fuel saving benefits from CDO are in the region of x10 those from CCO.

(*) It should be noted that the achievement of 100% CCO and CDO across the European network may not be possible for a number of reasons, such as safety (i.e. the need to keep aircraft separated by a certain distance or time), weather, capacity or ATCO workload, all of which may be considered as interdependencies, while small inefficiencies in the system are required to operate a flexible and operationally efficient network.

What are Continuous Climb and Descent Operations (CCO and CDO)?

What can air travel industry do to reduce noise pollution?

The European CCO and CDO Task Force

Historically in Europe, the implementation of CCO and CDO operations has been encouraged on an ‘as-much-as-you-can’ basis while, until recently, there has been no harmonised definition of what actually constitutes a CCO or CDO operation.

In addition, there has been no assessment of the potential network-wide benefits that could be realised by optimal CCO and CDO operations.

In 2015, a task force of European ATM stakeholders was created with the objective of agreeing harmonised definitions, metrics and parameters to measure CCO and CDO operations in Europe. The resulting harmonised definitions, metrics and parameters agreed by the Task Force are recommended to be used by any European ATM stakeholder for the measurement of CCO, CDO or vertical flight efficiency performance in order to enable harmonisation at international level.

The work of the Task Force is ongoing and is expected to be completed by 2019 with the delivery of an updated CDO Action Plan document and a “State of Play’ document on CCO/CDO. More information will be detailed on the website once it becomes available.