Detailed working notes on Continuous Climb Operations (CCO), the ICAO operational concept for departures defined in Doc 9993 (Continuous Climb Operations Manual) and PANS-OPS (Doc 8168). This folder expands the summary in topics/cco.md into per-aspect files so each can be read on its own.

Files in this folder#

• overview.md — what CCO is, environmental and efficiency rationale, and the Doc 9993 / PANS-OPS anchor.
• components.md — design principles, departure procedure design, ATC techniques, and FMS use that together produce a CCO outcome.
• blocks.md — CCO maturity / implementation phases (concept, design, procedure publication, ATC training, monitoring).
• threads.md — stakeholder strands (procedure design, ATC, flight operations, environmental authority) that must align for CCO benefit.
• modules.md — anatomy of a CCO procedure design (objective, procedure, technology, enablers, KPIs).
• enablers.md — PBN, ATC tools (DMAN), simulation, training, and airspace-design prerequisites.
• performance_objectives.md — KPAs (environment, fuel efficiency, noise) and the KPIs used to evidence CCO benefit.
• timeline.md — Doc 9993 publication, regional CCO uptake, and how CCO fits the GANP / ASBU APTA cadence.
• references.md — ICAO + PANS-OPS Vol II + external references.

Reading order#

Start with overview.md, then components.md to see what makes up a CCO outcome. Use blocks.md and threads.md to map the implementation journey and the stakeholders involved. Drill into modules.md, enablers.md, and performance_objectives.md for design and measurement detail. Use timeline.md for date context and references.md for citations.

Source basis#

Content is grounded in:

• ICAO Doc 9993, Continuous Climb Operations (CCO) Manual.
• ICAO Doc 8168 (PANS-OPS), Volume I (flight procedures, noise abatement) and Volume II (procedure design — departures).
• ICAO Doc 4444 (PANS-ATM) — clearance phraseology and separation practice that determines whether a published CCO can be flown.
• ICAO Annex 11 (Air Traffic Services) — airspace organisation and ATS route structure.
• ICAO Doc 9613 (PBN Manual) — PBN SIDs as the technical enabler.
• ICAO Doc 9750 (GANP) and the ASBU APTA thread.
• EUROCONTROL CCO/CDO joint guidance (web fallback where Doc 9993 is not in the local library).

Scope note#

CCO is a system-level outcome, not a single technique. It depends jointly on procedure design, airspace structure, ATC clearance practice, and flight crew execution. Files in this folder treat each of those facets, then bring them together in modules.md. CDO (the arrival counterpart) is documented separately under topics_detailed/cdo/; the two are typically planned and monitored as a pair.

What CCO is#

CCO stands for Continuous Climb Operation. It is an ICAO operational concept under which a departing aircraft climbs continuously, to the greatest extent possible, from brake release (or end of the initial noise-abatement segment) to its initial cruise flight level, using optimum climb engine thrust and optimum climb speeds, without intermediate level-offs. PANS-OPS (Doc 8168) defines CCO formally as "an operation, enabled by airspace design, procedure design and ATC, in which a departing aircraft climbs continuously, to the greatest possible extent, by employing optimum climb engine thrust and climb speeds until reaching the cruise flight level".

CCO is therefore a system-level outcome, not a piece of equipment or a single technique. It is delivered jointly by the published departure procedure, the surrounding airspace structure, the ATC clearance practice, and the flight crew's thrust and speed schedule.

Why it matters — environmental and efficiency rationale#

Aircraft burn fuel least efficiently at low altitudes and high thrust. Every minute spent levelled off below the optimum climb profile costs fuel and produces avoidable CO2 and noise. The headline drivers for CCO are therefore:

• Fuel efficiency. Removing low-altitude level-offs of a few minutes per flight saves on the order of tens of kilograms of fuel per movement. Over a busy departure runway this aggregates into meaningful annual fuel and cost reductions.
• CO2. Approximately 3.16 kg of CO2 is produced per kilogram of jet fuel burned. Fuel saved through CCO translates directly into emissions saved, supporting State Action Plans submitted under Annex 16 and CORSIA.
• Community noise. A continuous climb reaches noise-screening altitudes faster, reducing community noise exposure beneath the departure track. Trials have reported noise reductions of several decibels at near-airport monitoring points.
• Predictability and capacity. A predictable vertical profile makes conflict detection easier and can support higher TMA throughput by removing tactical level capping as the default conflict-resolution tool.
• Safety. Fewer altitude transitions mean fewer level-bust opportunities and reduced thrust-management workload during the busiest phase of flight.

ICAO anchor — Doc 9993 and PANS-OPS#

The primary ICAO document is Doc 9993 — Continuous Climb Operations (CCO) Manual. It is the reference for States, ANSPs, procedure designers, operators and ATC on how to plan, design, publish, fly, and monitor CCO, and how to balance CCO against the competing demands of other ATM operations.

PANS-OPS (Doc 8168) anchors CCO at two levels:

• Definition. Volume I and Volume II carry the formal CCO definition cited above.
• Design obligation. Doc 8168, Volume II, Part I, Section 3, Chapter 2, §2.2.1 states that departure procedure design "should consider the environmental and efficiency advantages afforded by implementation of a continuous climb operation (CCO)", with a note pointing to Doc 9993.
• Operational recognition. Doc 8168, Volume I, Part V, Chapter 3, §3.1.1 recognises that CCO and CDO can enhance safety, capacity, and efficiency, and benefit the environment.

Surrounding documents fill in the other facets:

• Doc 4444 (PANS-ATM) — clearance phraseology, vertical separation, and flow management practice that determine whether a published CCO profile can actually be flown.
• Annex 11 (Air Traffic Services) — airspace organisation and ATS route structure that frame CCO feasibility.
• Doc 9613 (PBN Manual) — identifies CDO/CCO as environmental motivators in the airspace concept (Doc 9613, Part A, §2.2.1) and frames PBN SIDs as the key technical enabler.
• Doc 9750 (GANP) — captures CCO under the ASBU APTA thread (PBN SID/STAR and CCO basic elements) as an environmental and efficiency lever.

What CCO is not#

• Not a single procedure. A "CCO SID" is not a category of procedure on its own; CCO is the outcome that a well-designed SID, airspace, and ATC clearance combine to produce.
• Not a clearance phrase. There is no specific "CCO clearance" in PANS-ATM. ATC supports CCO through the levels and speeds it issues, not through a special instruction.
• Not unconstrained climb. Where altitude or speed restrictions are required for traffic, terrain, airspace, or noise, they are designed in. CCO targets the unnecessary constraints — those imposed tactically or because the route structure forces a level-off below arrival or transit flows.
• Not the same as CDO. CDO is the arrival counterpart. The two are usually planned together because the same TMA structure constrains both, and gains on departure can be offset by losses on arrival if not co-designed.

CCO is delivered by four components working together. None of them on its own is sufficient; a State that publishes a "CCO-friendly" SID but keeps tactical level capping in its TMA, or a controller who issues unrestricted climb on a SID that has unnecessary "at" altitudes, will not achieve a continuous climb.

1. Design principles#

The PANS-OPS design principles that frame CCO are:

• Continuous gradient where possible. PANS-OPS, Volume II, Part I, Section 3, Chapter 2, §2.2.1 directs that departure procedure design "should consider the environmental and efficiency advantages afforded by implementation of a continuous climb operation (CCO)". The procedure should support an unbroken climb gradient unless an explicit obstacle, airspace, or noise reason requires otherwise.
• Standard procedure design gradient (PDG) of 3.3 per cent. The PDG begins 5 m (16 ft) above the departure end of the runway. Where obstacles intrude on the obstacle identification surface, a steeper PDG is published rather than a level-off.
• Altitude windows, not single altitudes. Aircraft performance varies widely (light vs heavy, hot/high). Designs that publish a vertical window — minimum and maximum — accommodate that variation while still constraining traffic where required.
• No unnecessary "at" altitudes. Each altitude restriction is scrutinised: is it driven by terrain, airspace boundary, or arrival conflict, or is it legacy text? "Window" restrictions ("at or above") preserve continuous climb whenever possible.
• Speed restrictions only where required. Speed caps below 10,000 ft follow national rules and noise-abatement design but should not be added to a SID for tactical convenience.

2. Departure procedure design#

Procedure design choices that materially affect CCO:

• PBN SID over conventional. PBN SIDs (RNAV 1 / RNP 1) allow more precise lateral routing, more compact spacing from arrival flows, and publication of vertical path information. Doc 9613 (PBN Manual) identifies CDO/CCO as environmental motivators that the airspace concept must address (Doc 9613, Part A, §2.2.1).
• Strategic deconfliction with arrivals. Departure routes are chosen so that climbing traffic does not cross descending arrival streams at the same level, removing the structural reason for tactical level-off.
• Realistic noise-abatement segments. Where NADP 1 or NADP 2 procedures apply (see PANS-OPS Volume I, Part V), the segments are designed to support, not break, continuous climb after the noise segment ends.
• Coordination with adjacent airspace. SIDs that hand off to neighbouring TMAs or upper sectors at sensible levels avoid the "stop-climb at FL150" syndrome where a sector boundary forces capping.

3. ATC techniques#

ATC translates a CCO-capable design into an actual continuous climb:

• Issue climb early to a high level. Where traffic permits, the initial clearance is to a flight level at or close to planned cruise, rather than a low intermediate level that will need to be revised.
• Strategic, not tactical, conflict resolution. Vertical, lateral, or temporal separation from arrivals/overflights is built into the airspace structure and timing rather than achieved by capping a departure.
• Harmonised phraseology per PANS-ATM. Standard climb instructions per Doc 4444; avoid unnecessary "maintain FLxxx" caps.
• Coordination with upstream / downstream sectors. Cross-sector and cross-FIR coordination prevents the receiving sector from imposing a level cap immediately after handover.
• Departure manager (DMAN) support. A DMAN that pre-sequences pushbacks and runway access reduces the need to hold or cap departures on the climb to manage runway demand.

4. FMS use and flight crew technique#

The aircraft side of CCO:

• Optimum climb thrust and speed schedule. The FMS climb mode (or the operator's performance manual) sets the thrust limit and the target climb speed (often a CAS/Mach schedule) that minimise total climb fuel for the planned cruise level and weight.
• FMS-coded SIDs. A SID that loads cleanly into the FMS — including any altitude windows and speed constraints — lets the autoflight system fly the published vertical path without crew workaround.
• Stable thrust management. Step changes in thrust during climb (to meet a tactical level cap, then accelerate again) waste fuel and increase noise; a single climb thrust setting is preferred.
• Awareness of CCO intent. Crews who know the SID is designed for CCO are better placed to request unrestricted climb early when traffic permits, rather than accept a low intermediate level.

How the components combine#

A useful mental model is a four-link chain: design, airspace, ATC, crew. The chain is only as strong as its weakest link. The operational benefit shows up only when all four are aligned. This is why CCO implementation is a stakeholder programme, not a procedure-design exercise; see threads.md for the stakeholder strands and blocks.md for the implementation phases that bring them into alignment.

CCO does not have its own ICAO "Block" structure in the ASBU sense; it appears as a basic element under the APTA thread (APTA-B0 PBN SID/STAR and CCO basic elements). For planning purposes, however, it is useful to think of CCO implementation as a sequence of maturity phases that any State or airport progresses through. The phases below mirror the structure used in Doc 9993 (Continuous Climb Operations Manual).

Phase 1 — Concept and feasibility#

Theme. Decide whether CCO is the right intervention and frame the expected benefit.

Activities:

• Form a multi-stakeholder working group (CAA, ANSP, airport, airline operations, environmental authority, local community where relevant).
• Baseline the current departure performance: typical level-off time and altitude, additional fuel burn, noise contour, departure delay.
• Identify the airspace, procedure, and traffic-mix factors driving current level-offs (arrival conflict, terrain, sector boundaries, military airspace).
• Set qualitative goals (reduce average level-off time, narrow the noise contour, reduce CO2 per movement) and an early KPI shortlist.

Exit criterion: a documented case for CCO at the airport / TMA in question, with stakeholder endorsement.

Phase 2 — Airspace and procedure design#

Theme. Translate the case into a redesigned departure environment.

Activities:

• Redesign the airspace so departure flows are strategically separated from arrival and transit flows at the levels of conflict.
• Redesign or replace SIDs as PBN procedures (RNAV 1 / RNP 1) per Doc 9613 and Doc 8168 Volume II. Apply the design principles in components.md (continuous gradient, altitude windows, no unnecessary "at" altitudes).
• Coordinate with adjacent FIRs / upper-area control on hand-off levels.
• Validate the design with fast-time and real-time simulation (see enablers.md).
• Conduct safety assessment per Annex 19 / Doc 9859 and obstacle assessment per PANS-OPS Volume II.

Exit criterion: design package ready for State approval and AIP publication.

Phase 3 — Procedure publication and AIP integration#

Theme. Make the new design available to industry.

Activities:

• AIP amendment cycle: publish the new SIDs, airspace structure, and any changed climb constraints. Coordinate AIRAC effective date with charting providers.
• FMS database coding (ARINC 424) — verify navigation database vendors encode the procedure faithfully, including altitude windows.
• Update local instructions / operational documents at the ANSP.
• Brief affected airline operators well in advance of the AIRAC date.

Exit criterion: SID active in AIP and FMS databases on the AIRAC date; charting available to all users.

Phase 4 — ATC training and rollout#

Theme. Embed the CCO mindset in ATC operations.

Activities:

• Refresh controller training on CCO intent, the new SIDs, and the expectation to issue early high-level clearances when traffic permits.
• Update local letters of agreement with adjacent units.
• Adapt DMAN configuration so that pre-departure sequencing supports unrestricted climb.
• Communicate to flight crews (via airline ops and ATIS notes where appropriate) that CCO is intended.
• Run a transition period with enhanced supervision and incident reporting.

Exit criterion: ATC unit operating to the new procedure without exceptional support.

Phase 5 — Monitoring and continuous improvement#

Theme. Measure what is delivered and tune the design.

Activities:

• Collect KPIs (see performance_objectives.md): level-off time per departure, additional fuel burn vs. unimpeded, vertical inefficiency, noise contour comparison, CO2 per movement.
• Compare against baseline from Phase 1; report internally and to the regional planning forum (e.g. APANPIRG, MIDANPIRG).
• Identify residual constraints — sector boundaries, military airspace, conflicting CDOs — and feed them into the next design cycle.
• Update Doc 9993-aligned implementation reporting and State Action Plan for environment.

Exit criterion: a closed loop where CCO performance is reviewed periodically and the design is refreshed as traffic evolves.

Phase dependency principle#

Phases must be sequenced. Common failure modes:

• Publishing PBN SIDs without redesigning airspace: tactical level capping persists, predicted benefit does not materialise.
• Designing for CCO without consulting adjacent FIRs: hand-off levels force capping despite the local design.
• Skipping ATC training: controllers continue legacy practice and override the published continuous climb intent.
• Skipping monitoring: no evidence base to defend the investment or refine the design.

Mapping to the ASBU APTA thread#

For planners reporting against the GANP / ASBU framework, CCO maturity maps loosely as follows:

• APTA-B0 basic CCO elements — Phases 1–3 above; published CCO at major airports.
• APTA-B1 advanced PBN elements — Phases 4–5 above; CCO routinely flown, monitored, and tuned.

The detail is maintained on the ICAO GANP Portal (https://ganpportal.icao.int/) under the APTA thread; treat the local phases above as a planning aid rather than a substitute for the portal.

CCO is a system-level outcome. Doc 9993 (Continuous Climb Operations Manual) emphasises that no single stakeholder can deliver it; success depends on coordinated work across four strands. This file describes those strands and the interfaces between them.

The strands are the people analogue of the ASBU "Threads" in topics_detailed/asbu/threads.md. Each carries its own decisions, artefacts, and failure modes.

1. Procedure design (CAA / instrument flight procedure designers)#

Role. Produce the published SIDs and the obstacle assessment that sit behind them.

Decisions in scope:

• PBN navigation specification (RNAV 1, RNP 1, RNAV 5).
• Procedure design gradient and any steeper gradients required for obstacles (PANS-OPS Volume II, Part I, Section 3, Chapter 2).
• Altitude restrictions (window vs. "at"), speed restrictions.
• Noise abatement segments (NADP 1 / NADP 2 framing, per PANS-OPS Volume I, Part V).
• Coordinated hand-off levels with the en-route designer.

Failure modes:

• Carrying legacy "at" altitudes forward into a redesign because no one re-justified them.
• Designing in isolation from arrival flows: the SID is "CCO-friendly" on paper but conflicts with a STAR that forces tactical capping.
• Insufficient coordination with the FMS database vendor: the published procedure does not load cleanly.

Interface to other strands: hands an FMS-codable procedure and a design rationale to ATC and the AIM/AIP function; receives operational performance data back from monitoring.

2. Air traffic control (ANSP — TMA and approach units)#

Role. Translate the published procedure into a continuous climb in real time.

Decisions in scope:

• Sector design and airspace volumes (with airspace planners).
• Default climb clearance levels per SID and per traffic situation.
• Use of departure manager (DMAN) for pre-departure sequencing.
• Coordination procedures with adjacent sectors and FIRs to preserve climb on hand-off.
• Local controller instructions, conformance monitoring, supervisor oversight.

Failure modes:

• Persistence of tactical level capping despite redesigned airspace, driven by individual controller habit rather than necessity.
• Hand-off levels with the next sector forcing capping just before hand-off.
• Lack of feedback loop: controllers do not see the fuel and noise consequence of capping, so it remains the default conflict-resolution technique.

Interface to other strands: receives the published SID and design rationale; coordinates with flight ops on routine clearances; provides operational data to monitoring.

3. Flight operations (airlines / operators / pilots)#

Role. Fly the published procedure with optimum thrust and speed.

Decisions in scope:

• FMS performance database accuracy (climb profile, weight, wind).
• Standard operating procedures for thrust setting and speed schedule in climb.
• Crew training on CCO intent and on requesting unrestricted climb when traffic permits.
• Fleet equipage with FMS / nav database appropriate to the SID navigation specification.
• Fuel-policy alignment so that the expected CCO fuel saving is recognised in dispatch planning.

Failure modes:

• Operator SOPs that override FMS optimum climb to meet a self-imposed speed cap below required minimums.
• FMS databases that do not represent published altitude windows faithfully.
• Crews who do not request a higher initial climb level when traffic clearly permits it.

Interface to other strands: receives published procedures and ATC expectations; provides actual-fuel-burn data and crew feedback into the monitoring loop.

4. Environmental authority and community engagement#

Role. Provide the environmental rationale and the social licence to operate, and validate the noise / emissions outcome.

Decisions in scope:

• Noise abatement strategy (preferred runways, NADP choice, night restrictions).
• Noise monitoring station placement and reporting.
• Air-quality and CO2 reporting under State Action Plans (Annex 16, Volume IV / CORSIA).
• Community engagement around proposed airspace changes.

Failure modes:

• Noise constraints written without regard to climb performance: e.g. NADP segments terminating at a level that forces immediate capping.
• CO2 / fuel benefits claimed without measurement; loss of credibility with the community.
• Airspace redesign blocked late in the cycle by community objection that should have been engaged earlier.

Interface to other strands: provides environmental boundary conditions to design and ATC; consumes monitoring data to evidence outcomes.

Cross-strand coordination — the glue#

A typical governance structure has:

• A CCO programme board with representatives from each strand, chaired by the CAA or ANSP.
• A CCO/CDO joint working group (most CCO design questions touch CDO and vice versa).
• Periodic performance review against agreed KPIs (see performance_objectives.md).
• A clear change-control path: any proposal that affects the published SID, airspace, or operational procedure flows through the same body.

Doc 9993 sets out a similar governance pattern; the EUROCONTROL CCO/CDO joint guidance (web fallback) provides a worked-example governance template that many ANSPs use as a starting point.

This file applies the ASBU "module" anatomy to a CCO procedure design. The aim is to give a CAA / ANSP team a checklist they can fill in once per CCO design package, mirroring how a GANP module is captured on the ICAO GANP Portal.

A CCO design package typically covers a runway end (or a small set of related runway ends) at a single airport, plus the surrounding TMA sectors that the SIDs traverse.

Anatomy of a CCO design#

1. Title and identifier#

A local identifier such as CCO-OPLA-RWY25R-2026 or KHI-CCO-package-1, plus a plain-language title (e.g. "Karachi RWY25R PBN SIDs and CCO redesign").

2. Operational improvement description#

What changes operationally for departing aircraft from this runway end. For example: replacement of legacy conventional SIDs with PBN RNP 1 SIDs that publish altitude windows instead of mandatory level constraints; revised airspace handover with the en-route sector at a higher level.

3. Performance objective and applicable KPAs#

The "why". The package should be tagged with one or more performance objectives. Typical CCO objectives:

• Reduce fuel burn and CO2 per departure. KPAs: environmental impact, flight efficiency, cost-effectiveness.
• Reduce community noise exposure under the departure track. KPAs: environmental impact.
• Improve departure throughput / predictability. KPAs: capacity, predictability.
• Reduce ATC workload on tactical level capping. KPAs: safety, capacity.

4. Procedure element#

Procedural changes anchored in ICAO PANS:

• PANS-OPS (Doc 8168), Volume II — departure procedure design, including the §2.2.1 obligation to consider the environmental and efficiency advantages of CCO.
• PANS-OPS (Doc 8168), Volume I — pilot/operator procedures for noise abatement (Part V) and CCO/CDO recognition (Part V, Chapter 3, §3.1.1).
• PANS-ATM (Doc 4444) — clearance phraseology, vertical separation, flow management.
• Local AIP changes — SID charts, airspace boundaries, supplementary procedures, AIRAC schedule.

5. Technology element#

Systems used to design, publish, fly, and monitor the procedure:

• Procedure design tools that meet PANS-OPS Volume II criteria.
• FMS / nav database coding (ARINC 424) of the new SIDs.
• DMAN at the airport, where deployed, configured to support unconstrained climb.
• Surveillance (Mode S, ADS-B, MLAT) sufficient for strategic separation rather than tactical capping.
• Flight data and noise monitoring systems for KPI collection.

6. Human performance element#

• Controller training on the new SIDs, on issuing early high-level clearances, and on the CCO intent.
• Pilot briefing and operator SOP updates.
• Procedure designer continuing competency on PANS-OPS amendments.
• AIM officer training on AIRAC publication for the change.

7. Standards basis#

• Annex 11 — ATS provision and airspace organisation.
• Annex 6 — operator equipage and operational authorisations.
• Annex 10, Volume I — GNSS / PBN navigation infrastructure.
• Annex 14 — aerodrome data feeding procedure design.
• Annex 15 / Doc 10066 (PANS-AIM) — quality of aeronautical data underlying the published procedure.
• Annex 16, Volume IV — CORSIA reporting context for CO2 benefit.
• Annex 19 — safety management of the change.

8. Enablers#

The infrastructure, regulatory, training, and institutional prerequisites. See enablers.md for the catalogue. At a minimum:

• PBN published-procedure capability at the State.
• Surveillance enabling strategic separation.
• DMAN or equivalent sequencing where runway demand justifies it.
• Simulation capability (fast-time and real-time) for validation.
• Trained controllers, briefed operators, FMS-coded procedure.

9. Dependencies#

Other ATM elements that must be in place:

• PBN approach / arrival procedures at the same airport (otherwise the design optimises departures while arrival flows still force tactical capping).
• CDO design at the same airport — CCO and CDO usually share TMA structure and must be co-designed.
• Adjacent FIR / upper-area-control coordination on hand-off levels.
• A-CDM / DMAN maturity if departure demand is being managed proactively.

10. KPI linkage#

Quantitative measures attached to the package — see performance_objectives.md for the catalogue. Typical CCO KPIs:

• Average level-off time below top-of-climb per departure.
• Additional fuel burn vs. unimpeded climb (kg per movement).
• Vertical inefficiency (cruise vs. optimum).
• Noise contour change at agreed monitoring points (dB).
• CO2 per movement (derived from fuel).

11. Region applicability#

Most CCO designs are airport- and TMA-specific. Common regional variations:

• Mountainous / hot-and-high airports: different climb performance, different obstacle environment.
• High-density TMAs with mixed-mode runways: arrival/departure conflicts dominate the design problem.
• Oceanic and remote: less relevant; CCO is a TMA-area problem.

12. Implementation guidance#

• Doc 9993 — Continuous Climb Operations Manual (primary).
• EUROCONTROL CCO/CDO joint guidance — worked examples (web fallback).
• Regional planning documents — APAC Seamless ATM Plan, MID Air Navigation Strategy, European ATM Master Plan.

Worked example — illustrative CCO package#

• Title. Sample TMA RWY25 CCO package.
• Operational improvement. Three legacy SIDs replaced by RNP 1 SIDs with altitude windows; arrival flow re-routed laterally to remove vertical conflict at FL130; en-route hand-off raised from FL150 to FL240.
• KPAs. Environment, efficiency, predictability.
• Procedure. PANS-OPS Volume II Part I §2.2.1 design rationale; PANS-ATM Doc 4444 phraseology unchanged; local AIP amendment.
• Technology. RNP 1 procedure design; ARINC 424 coding; DMAN re-tuned.
• Enablers. ADS-B coverage; controller training; airline operator briefing; simulator validation.
• Dependencies. Companion CDO redesign for the same TMA.
• KPIs. Target 90 s reduction in average level-off time per departure; 60 kg fuel saved per movement; 2 dB noise reduction at agreed monitor.

An enabler for CCO is a supporting element without which the intended environmental and efficiency benefit cannot be delivered. Doc 9993 (Continuous Climb Operations Manual) frames CCO as the joint product of airspace design, procedure design, ATC, and flight crew execution — each of which has its own underpinning enablers. This file catalogues those prerequisites in seven groups.

1. Performance-Based Navigation (PBN)#

PBN is the single most important technical enabler for CCO. Doc 9613 (PBN Manual), Part A, §2.2.1 explicitly identifies CDO/CCO as environmental motivators that the airspace concept must address.

What PBN brings to CCO:

• Lateral precision that lets departure tracks be drawn closer to arrival/transit flows without losing separation, removing the need to separate flows by tactical level cap.
• Vertical path information on the published SID so the FMS can fly a coherent climb profile.
• PBN navigation specifications appropriate to TMA design:
  • RNAV 1 — typical TMA SID specification.
  • RNP 1 — more demanding accuracy / containment, supports closer route spacing.
  • A-RNP — advanced applications including radius-to-fix legs where curvature is needed.
• PBN approach procedures in the same TMA so that arrival flows are also precisely routed and the design problem is symmetrical.

A State that has not deployed PBN SIDs cannot in practice run a CCO programme; the legacy SID design is itself the constraint.

2. ATC tools — particularly DMAN#

ATC tooling that supports continuous climb:

• Departure manager (DMAN). Sequences pushbacks and runway access so that a departure, once airborne, has a clear climb path. Reduces the need to hold a departure low to manage downstream conflict.
• Arrival manager (AMAN) / extended AMAN (XMAN). AMAN and XMAN shape arrival rates; predictable arrivals are easier to deconflict strategically from climbing departures.
• Surface manager (SMAN). Coordinates ground movement so the runway is fed at the rate the DMAN expects.
• Flight data processing. Trajectory prediction accurate enough to see departure/arrival/transit conflicts strategically, ahead of tactical intervention.
• Surveillance. Mode S, ADS-B, multilateration — coverage and performance sufficient to support strategic separation rather than reflex tactical capping.
• Conformance monitoring. Tools that show controllers and supervisors when published vertical profiles are not being flown — closing the feedback loop on level-off practice.

3. Simulation and validation#

Before publication and after change, simulation is essential to de-risk a CCO design:

• Fast-time simulation for the airspace and route-network options; evaluates capacity, conflict density, and predicted CCO performance at scale.
• Real-time simulation with controllers and pseudo-pilots to validate the procedure under realistic workload and human-factor conditions.
• Flight simulator validation by airline training departments to confirm that the SID flies cleanly in the flight deck.
• FMS database verification — a separate check that ARINC 424 coding faithfully represents the procedure designer's intent, particularly altitude windows.

4. Training#

Training is needed across all four stakeholder strands:

• Procedure designers — continuing competency on PANS-OPS amendments, in particular Volume II departure design.
• Controllers — refresh on the new SIDs, on the CCO intent, on early high-level clearance practice, and on conformance monitoring.
• Pilots — operator briefing on the new SIDs and on the expectation of optimum thrust/speed; FMS handling of altitude windows.
• Engineering and AIM — quality control on the published aeronautical data; AIRAC discipline.
• Supervisors and managers — interpretation of CCO KPIs, intervention when conformance drifts.

5. Standards (SARPs)#

Annex provisions that underpin CCO:

• Annex 6 — Operation of Aircraft. Equipment carriage and operational authorisations for PBN.
• Annex 10, Volume I — Aeronautical Telecommunications (Radio Navigation Aids). GNSS standards underpinning PBN.
• Annex 11 — Air Traffic Services. Airspace organisation, ATS route structure, ATFM, language.
• Annex 14 — Aerodromes. Aerodrome data quality feeding procedure design.
• Annex 15 — Aeronautical Information Services / PANS-AIM (Doc 10066). Quality regime for the data underlying the published procedure.
• Annex 16, Volumes II–IV — Environmental Protection. Noise and emissions context (CORSIA in Volume IV).
• Annex 19 — Safety Management. SMS treatment of the change.

6. Regulatory framework#

• State approval for PBN operations under Annex 6.
• AIP / AIRAC discipline under Annex 15 / PANS-AIM.
• Environmental approvals required for airspace change in many States, including community consultation.
• Safety oversight of the design and the operational change per Annex 19 and the State Safety Programme.
• Charging policy (Doc 9082) supporting the ANSP investment in airspace redesign and DMAN deployment.

7. Institutional and inter-State#

• Letters of agreement between the airport's TMA unit and adjacent area control / military units, raising the hand-off level so that climb is preserved across boundaries.
• Cross-FIR coordination where SIDs cross an FIR boundary while still climbing.
• Regional planning fora — APANPIRG, MIDANPIRG, EANPG, etc. — endorsing harmonised CCO/CDO implementation across the region.
• EUROCONTROL CCO/CDO joint guidance (web fallback) as a cross-State reference for design and monitoring techniques.

How enablers are managed in practice#

A CCO programme tracks enablers as part of the design package (see modules.md). A common failure mode is to deploy a "CCO SID" without the airspace redesign, the DMAN tuning, the controller training, or the operator briefing — and then find that the predicted benefit does not materialise. Doc 9993 explicitly warns that CCO is not delivered by procedure design alone.

CCO is justified by the performance benefit it delivers and is tracked against quantified KPIs. The terminology is the same as for the wider ASBU framework — Key Performance Areas (KPAs) from Doc 9854 and KPIs from Doc 9883 (Manual on Global Performance of the Air Navigation System) — applied to the specific phenomena CCO targets.

The chain is:

KPA  --(measured by)-->  KPI  <--(targeted by)--  CCO performance objective  --(achieved by)-->  CCO design package

Key Performance Areas relevant to CCO#

Of the eleven KPAs in Doc 9854 / Doc 9883, CCO most directly affects:

1. Environmental impact. Fuel burn, CO2, NOx, and community noise. The headline CCO KPA.
2. Flight efficiency. Vertical profile efficiency in particular — how close the actual climb is to an unimpeded climb to the planned cruise level.
3. Cost-effectiveness. Operator fuel cost and ANSP unit cost benefit from removing avoidable level-offs.
4. Capacity. Predictable departure profiles can support higher TMA throughput and reduce reactionary delay.
5. Predictability. A continuous climb profile is easier to plan against than one with tactical capping.
6. Safety. Fewer altitude transitions reduce level-bust opportunities.

CCO performance objectives#

A CCO design package can be tagged with one or more of the following performance objectives, all of which are recognised under Doc 9993 and echoed in Doc 9613 (PBN Manual), Part A, §2.2.1 as environmental motivators for airspace concept change.

• PO — Reduce fuel burn and CO2 per departure. Delivered by PBN SID redesign, airspace redesign, DMAN, controller technique.
• PO — Reduce community noise exposure under the departure track. Delivered by reaching noise-screening altitude faster; supported by appropriate NADP framing.
• PO — Improve vertical profile efficiency. Delivered by removing unnecessary altitude restrictions and tactical capping.
• PO — Improve departure predictability. Delivered by deterministic vertical profiles and reduced tactical intervention.
• PO — Reduce ATC tactical workload on departures. Delivered by strategic deconfliction designed into airspace and procedures.

Key Performance Indicators (KPIs)#

KPIs that an ANSP / CAA typically reports on a CCO programme. Many of these are the metrics Doc 9993 recommends for monitoring CCO benefit; some are drawn from EUROCONTROL CCO/CDO joint guidance (web fallback) where Doc 9993's local-library coverage is incomplete.

Environmental KPIs#

• Fuel burn per movement (kg). Total fuel burned from brake release to top of climb (or to a reference altitude such as FL100 / FL245).
• Additional fuel burn vs. unimpeded (kg). Difference between actual climb fuel and modelled unimpeded climb fuel; the headline CCO inefficiency metric.
• CO2 per movement (kg). Derived from fuel using ~3.16 kg CO2 / kg jet fuel; reported into State Action Plans under Annex 16 / CORSIA.
• Noise contour area (km^2). Area enclosed by an agreed noise contour (e.g. Lden 55 dB) under the departure track.
• Noise level at monitoring point (dB). Single-event Lmax or SEL at agreed community monitoring stations.

Flight-efficiency KPIs#

• Time spent in level flight below top of climb (s per departure). The classic CCO metric — sums all level-off segments during climb.
• Number of level-offs per departure. Count of distinct level segments below cruise.
• Vertical inefficiency. Integrated altitude deficit vs. unimpeded climb profile, in altitude-time units.
• Altitude reached at fixed distance from DER. Altitude at, say, 20 NM and 40 NM from the departure end of the runway, against an agreed benchmark.

Capacity and predictability KPIs#

• Standard deviation of climb time to top of climb. Spread between best and worst departures.
• Departure throughput (movements per hour). Sustained rate at the runway, especially under DMAN.
• Reactionary delay. Delay caused by departures interfering with the next departure or arrival.

Safety KPIs#

• Level-bust rate per movement. Reduced when the climb is continuous and altitude transitions are fewer.
• Loss-of-separation events per flight hour in the TMA — should not increase as a result of removing tactical capping.
• STCA / MSAW alerts per movement — secondary safety net evidence.

ATC workload proxies#

• Climb-related instructions per departure. Number of altitude or speed instructions issued after take-off.
• Conformance to published vertical profile (%). Proportion of departures that fly the published altitude windows without intervention.

How CCO performance is reported#

• Globally — into the ICAO ASBU implementation monitoring under the APTA thread, consolidated through the GANP review cycle.
• Regionally
  • APAC: APANPIRG performance reporting and the Seamless ATM Plan.
  • MID: MIDANPIRG and the MID Air Navigation Strategy.
  • EUR: EUROCONTROL Performance Review Body and LSSIP cycle, with CCO covered specifically in CCO/CDO joint reporting.
• Nationally — State Action Plans on environmental protection (under Annex 16 / CORSIA), national air navigation plans, and the airport / ANSP performance scheme.

Why the KPI link matters#

Tying a CCO design package to an explicit performance objective and a KPI keeps the programme honest. It forces the question "what measurable problem does this fix?" during business-case development, and it gives oversight bodies the language to ask whether the deployed capability is delivering the promised benefit. Doc 9993 reflects this pattern: implementation guidance, governance, and monitoring are treated as one continuous loop, not as separate phases.

Three timelines to keep distinct#

When discussing CCO "dates", separate three things:

1. ICAO doctrine timeline — when ICAO published or amended the manuals and PANS that frame CCO.
2. GANP / ASBU timeline — when CCO appears as a basic element in the APTA thread of the ASBU framework.
3. Regional / national uptake timeline — when individual States, ANSPs, and airports publish CCO-friendly procedures and report benefit.

Mixing these up leads to false claims that a State is "behind" or "ahead" of CCO when the only meaningful measure is the State's own implementation against its own milestones.

ICAO doctrine timeline#

The key inflection points are 2010 (CDO Manual establishes the template), 2013 (CCO Manual published), and the subsequent PANS-OPS amendment cycle that placed CCO within mainstream procedure design.

GANP / ASBU timeline for CCO#

CCO does not have its own ASBU thread; it appears under the APTA (Optimization of Approach Procedures including Vertical Guidance) thread, alongside PBN SID/STAR work, with parallel mentions under environmental performance objectives.

GANP edition       ASBU role of CCO
4th (2013)         CCO listed as a basic element under APTA-B0,
                   together with PBN SID/STAR and CDO.
5th (2016)         Block dates re-baselined to 2013/2019/2025/2031;
                   CCO retained as APTA-B0/B1 basic element.
6th (2019)         ASBU module catalogue moved to the GANP Portal;
                   CCO now reflected dynamically there under APTA.
7th (2022)         Multi-layer GANP; basic building blocks (BBB)
                   concept; CCO continues as an APTA element with
                   environmental and efficiency performance objectives.

The current authoritative listing of CCO under APTA lives on the GANP Portal (https://ganpportal.icao.int/), not in the printed GANP volume.

Regional CCO uptake#

Regional uptake follows a broadly similar pattern: an early-mover phase in mature TMAs, a regional planning commitment, and then a longer tail as smaller airports redesign their SIDs.

Europe#

• 2010–2015. Early CCO/CDO trials at major hubs (Heathrow, Stockholm-Arlanda, Frankfurt, Amsterdam, Paris-CDG). EUROCONTROL publishes joint CCO/CDO guidance and starts pan-European monitoring.
• 2015–2020. CCO/CDO included as performance items in the European ATM Master Plan and in LSSIP reporting; PBN SID rollout continues under the Implementing Regulation on PBN.
• 2020 onwards. Routine CCO/CDO performance reporting through the Performance Review Body. EUROCONTROL CCO/CDO Action Plans drive airport-level improvement (web fallback for current state).

Asia/Pacific#

• 2013 onwards. Doc 9993 referenced by the APAC Seamless ATM Plan in its environmental and efficiency sections; CCO/CDO included as basic-element items.
• APANPIRG monitoring. Annual review under APANPIRG; major hubs in Singapore, Hong Kong, Tokyo, Sydney implement CCO-compatible PBN SIDs through the 2010s and 2020s.
• Regional projects. Bay-of-Bengal cooperative ATFM trial, ASIA region cross-FIR coordination programmes, all of which interact with CCO/CDO design at TMA boundaries.

Middle East#

• MID Air Navigation Strategy (under MIDANPIRG) lists CCO/CDO among environmental and efficiency performance objectives. Major hubs (Dubai, Doha, Abu Dhabi, Jeddah) progressively introduce PBN SIDs and CCO design.

Other regions#

• NAM (US/Canada). Optimum Profile Descent / Optimum Profile Climb programmes implemented under NextGen and Canadian equivalents; vocabulary differs from ICAO but objectives align.
• AFI, CAR, SAM. CCO / CDO addressed through the regional plans, with implementation typically tied to PBN approach rollouts at major international airports.

How to read a date in a CCO document#

When a CCO document uses a date, check which kind of date it is:

• "Doc 9993 (2013)" — ICAO publication date.
• "APTA-B0 from 2013" — Block availability date in the GANP / ASBU framework.
• "Airport X CCO programme launched 2018" — local implementation milestone.
• "30 per cent fuel-efficiency target by 2030" — regional or national performance ambition.

These are not interchangeable. The only meaningful measure of a State's CCO maturity is its own implementation plan against its declared milestones, monitored through the regional planning cycle and reported into ICAO under the GANP / ASBU framework.

Primary ICAO documents#

• Doc 9993 — Continuous Climb Operations (CCO) Manual. Primary ICAO reference for States, ANSPs, procedure designers, operators, and ATC on planning, designing, publishing, flying, and monitoring CCO, and on balancing CCO against the competing demands of other ATM operations. (Authoritative source — not in local library.)
• Doc 8168 — PANS-OPS, Volume I (Flight Procedures). Carries the formal CCO definition in the Definitions section and recognises in Part V, Chapter 3, §3.1.1 that CCO and CDO can enhance safety, capacity, and efficiency, and benefit the environment.
• Doc 8168 — PANS-OPS, Volume II (Construction of Visual and Instrument Flight Procedures). Carries the design obligation in Part I, Section 3, Chapter 2, §2.2.1: departure procedure design "should consider the environmental and efficiency advantages afforded by implementation of a continuous climb operation (CCO)", with a note pointing to Doc 9993. Part I, Section 3 also carries the standard procedure design gradient (3.3 per cent) and obstacle identification surface principles that frame CCO design.
• Doc 4444 — PANS-ATM. Clearance phraseology, vertical separation, and flow management practices that determine whether published CCO profiles can actually be flown.
• Doc 9613 — PBN Manual. Part A, §2.2.1 identifies CDO/CCO as environmental motivators in the airspace concept and frames PBN SIDs as the key technical enabler. Part B sets out the navigation specifications (RNAV 1, RNP 1, A-RNP) used in CCO-friendly SIDs.
• Doc 9750 — Global Air Navigation Plan (GANP). CCO appears under the ASBU APTA thread (PBN SID/STAR and CCO basic elements) as an environmental and efficiency lever. The live module catalogue is on the GANP Portal.
• Doc 9854 — Global Air Traffic Management Operational Concept. Source of the eleven KPAs (environment, flight efficiency, predictability, capacity, safety, etc.) used to justify CCO performance objectives.
• Doc 9883 — Manual on Global Performance of the Air Navigation System. Defines the performance management methodology (KPAs, KPIs, performance objectives) used to measure CCO benefit.
• Doc 8400 — PANS-ABC (Procedures for Air Navigation Services — Abbreviations and Codes). Defines the abbreviation "CCO" (Continuous climb operations) for use in aeronautical documents and ATS messaging.
• Doc 9931 — Continuous Descent Operations (CDO) Manual. Sister manual to Doc 9993; CCO and CDO are routinely planned together.

ICAO Annexes most relevant to CCO#

• Annex 6 (Operation of Aircraft). Operator equipage and operational authorisations underpinning PBN-based CCO.
• Annex 10, Volume I (Aeronautical Telecommunications — Radio Navigation Aids). GNSS standards underpinning PBN SIDs.
• Annex 11 (Air Traffic Services). Airspace organisation and ATS route structure that frame CCO feasibility through ATC clearance and separation services.
• Annex 14 (Aerodromes). Aerodrome data quality feeding procedure design.
• Annex 15 (Aeronautical Information Services) and Doc 10066 (PANS-AIM). Quality regime for the data underlying the published procedure.
• Annex 16 (Environmental Protection), Volumes II–IV. Engine emissions, CO2 reporting, and CORSIA — the environmental reporting framework that consumes CCO benefit metrics.
• Annex 19 (Safety Management). SMS treatment of the change.

Live / authoritative sources#

• ICAO GANP Portal — https://ganpportal.icao.int/ — live home of the ASBU framework, including the APTA thread under which CCO sits.
• ASBU Threads catalogue — https://ganpportal.icao.int/asbu/thread
• ICAO GANP overview page — https://www.icao.int/global-air-navigation-plan-ganp
• ICAO environmental protection (Doc 9993 context) — https://www.icao.int/environmental-protection/Pages/default.aspx

Regional implementation references#

• APAC Seamless ATM Plan (ICAO Asia/Pacific Regional Office) — APAC realisation of the ASBU framework, including CCO/CDO under environmental and efficiency objectives. Monitored by APANPIRG.
• MID Air Navigation Strategy (ICAO MID Regional Office) — MID realisation; monitored by MIDANPIRG.
• European ATM Master Plan (SESAR JU) and EUROCONTROL LSSIP cycle — EUR realisation and annual reporting; CCO/CDO covered as performance items.

EUROCONTROL — joint CCO/CDO guidance (web fallback)#

Where Doc 9993 itself is not in the local library, the EUROCONTROL CCO/CDO joint guidance is the most accessible authoritative implementation reference. Marked as web fallback.

• EUROCONTROL CCO/CDO action plans and joint guidance — https://www.eurocontrol.int/concept/continuous-climb-and-descent-operations
• EUROCONTROL "European Joint Industry CCO/CDO Action Plan" — joint paper between airlines, airports, ANSPs and the network manager, documenting design templates, KPI definitions, and worked monitoring examples used widely in Europe.
• EUROCONTROL CCO/CDO performance dashboards — periodic data on CCO/CDO performance at European airports (consult the EUROCONTROL performance review pages for the latest URL).

Industry and supporting references (web fallback where relevant)#

• SKYbrary, "Continuous Climb Operations (CCO)" — https://skybrary.aero/articles/continuous-climb-operations-cco — community reference summarising the ICAO concept and benefits. (Web fallback.)
• CANSO and IATA environmental performance publications — joint industry guidance on operational improvements including CCO. (Web fallback; consult current CANSO and IATA portals.)
• State Action Plans on CO2 emissions reduction activities filed with ICAO under the CORSIA framework — many list CCO/CDO as measures, and provide State-by-State implementation context.

Cross-references in this workspace#

• topics/cco.md — public summary version of this topic for the web app.
• topics_detailed/cdo/ — sister concept (Continuous Descent Operations); typically planned and monitored alongside CCO.
• topics_detailed/asbu/threads.md — ASBU APTA thread under which CCO is registered.
• topics_detailed/airspace_design/ — TMA structure underpinning CCO feasibility.
• topics_detailed/a_cdm/ — A-CDM and DMAN context that supports unrestricted climb on departure.