Detailed working notes on Airport Collaborative Decision Making (A-CDM). This folder expands the summary in topics/a_cdm.md into per-aspect files so each can be read on its own.

Files in this folder#

• overview.md — what A-CDM is, where it sits in the wider ICAO/ATM framework, and who uses it.
• components.md — the building components of the framework (information sharing, milestones, VTT, PDS, adverse conditions, DPI/NOP integration).
• blocks.md — A-CDM rollout phases / implementation maturity levels, and how the EUROCONTROL manual stages deployment.
• threads.md — the feature areas / pillars that run across A-CDM (information sharing, milestone tracking, slot management, network integration).
• modules.md — anatomy of an A-CDM milestone or sub-process: objective, procedure, technology, enablers, KPI links.
• enablers.md — supporting CNS/IT, procedures, training, regulation, certification.
• performance_objectives.md — KPAs (predictability, capacity, environment, cost) and the KPIs used to evidence A-CDM benefit.
• timeline.md — evolution of the EUROCONTROL Airport CDM Implementation Manual, ICAO Doc 9971 history, and deployment milestones.
• references.md — consolidated ICAO and external references for everything in this folder.

Reading order#

Start with overview.md, then components.md, then blocks.md and threads.md, then drill into modules.md, enablers.md, and performance_objectives.md. Use timeline.md for date context and references.md for citations.

Source basis#

Content is grounded in:

• ICAO Doc 9971 — Manual on Collaborative Air Traffic Flow Management.
• ICAO Doc 8126 — Aeronautical Information Services Manual (CDM as a discipline of quality-assured digital decision-making).
• ICAO Doc 10199 — PANS-IM (TOBT as the worked example of an information service tied to A-CDM).
• ICAO Doc 10066 — PANS-Aerodromes (aerodrome mapping data sets supporting CDM).
• ICAO Doc 4444 — PANS-ATM (ATFM provisions consumed by the A-CDM/NOP boundary).
• ICAO Doc 7030 — Regional Supplementary Procedures (CTOT phraseology: SAM, SRM, SLC, FLS, DES).
• ICAO Annex 11 (ATS, ATFM provisions) and Annex 14 Vol I (aerodrome mapping data, A-SMGCS).
• ICAO Doc 9750 (GANP) and the GANP Portal — ASBU threads ACDM-B0 and ACDM-B1.
• EUROCONTROL Airport CDM Implementation Manual (current edition).
• EUROCONTROL Specification for Airport Collaborative Decision Making (EUROCONTROL-SPEC-0157).
• EUROCONTROL Network Manager DPI Implementation Guide.
• EUROCONTROL A-CDM concept page: https://www.eurocontrol.int/concept/airport-collaborative-decision-making

What A-CDM is#

A-CDM stands for Airport Collaborative Decision Making. It is an operational concept that improves the efficiency and resilience of airport operations by having all partners — airport operator, aircraft operators, ground handlers, ATC tower, apron control, and the network manager — work together with full transparency on a shared, time-stamped picture of each turnround. The aim is to deliver the right aircraft to the right runway at the right time, with accurate take-off estimates fed into the Network Operations Plan (NOP) so that en-route flow management can plan with reliable inputs.

A-CDM is not a single system. It is a procedure framework supported by data exchange — TOBT, TSAT, the sixteen turnround milestones, and the DPI message family — between the airport's CDM platform and EUROCONTROL's Network Manager Operations Centre (NMOC), or an equivalent regional flow entity.

Where A-CDM sits in the ICAO / ATM framework#

A-CDM is the airport-level realisation of the wider Collaborative Decision Making (CDM) discipline that ICAO documents define for the whole ATM system:

1. Strategic / conceptual layer. Doc 8126 (AIM Manual), §1.5.1, frames CDM as taking ATM decisions collaboratively on quality-assured digital information rather than in isolation.
2. Information layer. Doc 10199 (PANS-IM) uses Set TOBT / Delete TOBT as the worked example of an information service, expressly tied to the A-CDM concept and its A-CDM partners (operators, ground handlers).
3. Aerodrome data layer. Annex 14 Vol I, Attachment A, §22.2.1 and Doc 10066 (PANS-Aerodromes), §5.3.3.3, require aerodrome mapping data sets accurate enough to support CDM, common situational awareness, and aerodrome guidance applications (the basis for AMDBs and A-SMGCS levels 1–4).
4. ATFM / network layer. Doc 4444 (PANS-ATM), Chapter 8, points to Doc 9971 (Manual on Collaborative ATFM) as the guidance material for collaborative flow processes that A-CDM feeds with departure estimates (TTOT) and consumes in the form of CTOTs issued under SAM/SRM (Doc 7030, §10.5).
5. Global plan layer. ICAO Doc 9750 (GANP) carries A-CDM as the ASBU thread ACDM with modules ACDM-B0 (airport CDM) and ACDM-B1 (full A-CDM-to-network-manager integration).

The de-facto detailed reference for implementation is the EUROCONTROL Airport CDM Implementation Manual and the underlying EUROCONTROL Specification for A-CDM (EUROCONTROL-SPEC-0157), which most non-EU airports connecting to NMOC also follow.

Who uses A-CDM#

A-CDM is collaborative by definition; its participants are the A-CDM partners:

• Airport operator — owns the airport operations database (AODB), stand allocation, surface management, and (typically) the A-CDM platform.
• Aircraft operators / airlines — own EOBT, manage TOBT updates from their operations control centre or via the handler.
• Ground handlers — execute the turnround; in most implementations they are the on-the-ramp owner of TOBT.
• ATC (tower and approach) — issue TSAT, build the pre-departure sequence, manage start-up clearance, and act as the airport-side interface to ATFM.
• Apron control — where it exists separately from tower, manages ground movement on the manoeuvring area.
• Network manager / regional flow entity — receives DPI messages, feeds the NOP, issues CTOTs.
• De-icing, fuel, security, customs, passenger and baggage systems — contribute milestone events into the shared picture.

Why A-CDM matters#

Without A-CDM, each partner plans in isolation against its own version of "now": the airline tracks the turnround, the handler tracks ramp activity, the tower tracks the runway sequence, the network manager computes a generic departure estimate from the filed flight plan. The result is double-counted slack, late-running turnrounds that surprise the runway sequence, runway sequences that surprise the network, and network estimates that miss reality.

A-CDM removes that mismatch by making one shared timeline the authoritative reference for the turnround. Two times in particular do the heavy lifting:

• TOBT (Target Off-Block Time) — owned by the operator/handler; the time the aircraft will be ready, doors closed, ready to push.
• TSAT (Target Start-up Approval Time) — issued by the tower; the time the aircraft can expect start-up clearance, sequenced against the pre-departure sequence and any CTOT.

The TOBT/TSAT pair is the heart of A-CDM: TOBT is the operator's commitment, TSAT is ATC's response. Around it, sixteen agreed milestones trigger updates, alerts, and DPI messages to the network manager so the NOP holds the airport's own departure estimates instead of generic ones.

Relationship to other initiatives in this repo#

• ASBU — A-CDM is the operational thread ACDM (Blocks 0 and 1).
• NOPS — A-CDM provides the airport-side input to network operations.
• SWIM — later A-CDM blocks rely on SWIM services for partner integration and NM exchange.
• Digital AIM — aerodrome mapping data sets feed surface management and the shared situational picture.
• A-SMGCS / surface management — close peer; A-SMGCS Level 3/4 and A-CDM share the same AODB and shared situational view.
• TBO — A-CDM contributes the airport boundary of trajectory-based operations: a reliable TTOT and AOBT at each end of the trajectory.

A-CDM is structured by the EUROCONTROL Airport CDM Implementation Manual into six concept elements that must be implemented together for full benefit. Implementing any one in isolation leaves the others unfounded.

The components are:

1. Information Sharing#

A common situational picture shared in real time between all partners. The data set typically includes:

• Flight plan data (callsign, type, EOBT, route, destination).
• Stand allocation and stand changes.
• TOBT, TSAT, CTOT (where issued), TTOT.
• Turnround milestone events (in-block, ground handling start, boarding start, aircraft ready, start-up request, start-up approved, off-block, take-off).
• ATFM regulation status, slot allocation messages, suspension status.
• De-icing status, where applicable.
• Adverse-condition declarations (LVP, snow plan, capacity reduction).

Information sharing is the enabling layer for everything else. Doc 8126 (AIM Manual), §1.5.1, defines the underlying discipline as taking ATM decisions collaboratively on quality-assured digital information rather than in isolation; Doc 10199 (PANS-IM) provides the information- service grammar (Set TOBT / Delete TOBT as the canonical worked example).

2. Milestones Approach#

Sixteen agreed milestones structure the turnround from inbound planning to airborne. Each milestone is an event with a planned and an actual time; deviations trigger alerts and DPI updates. The milestones run:

M1  ATC Flight Plan Activation (3 h before ELDT)
M2  EOBT - 2 h
M3  Take-Off from Origin Airport
M4  Local Radar Update / TMA entry
M5  Final Approach
M6  Landing (ALDT)
M7  In-Block (AIBT)
M8  Ground Handling Starts
M9  TOBT issued (target off-block confirmed by handler/operator)
M10 TSAT issued by tower
M11 Boarding Starts
M12 Aircraft Ready
M13 Start-Up Request
M14 Start-Up Approved (push/start)
M15 Off-Block (AOBT)
M16 Take-Off (ATOT)

The milestones are not arbitrary checkpoints; they are the events at which a partner's commitment becomes binding. M9 (TOBT issued) is the operator/handler commitment; M10 (TSAT) is ATC's response to that commitment; M14 closes the start-up loop; M16 closes the network loop.

3. Variable Taxi Time (VTT)#

Per-stand, per-runway taxi-out and taxi-in times derived from historical data. VTT is what turns TOBT into TSAT (subtracting buffer for the ramp-to-runway run), and TSAT into TTOT (adding the actual taxi-out estimate to take-off). Without VTT every flight would carry the same generic taxi assumption, and TTOT accuracy would collapse.

VTT tables are typically maintained per stand group, per runway-in-use configuration, and per traffic load band, refreshed from the airport's own movement data.

4. Pre-Departure Sequence (PDS)#

The tower's planning sequence built from TOBTs, ATFM slots, runway capacity, and wake categories. The PDS produces a TSAT for each flight and is the operational artefact that translates the airline's TOBT commitments into a runway-feasible plan. The PDS:

• Honours CTOTs from NMOC (a flight with a CTOT cannot push earlier than CTOT − taxi − start-up margin).
• Respects runway capacity declarations.
• Respects wake separation (RECAT or pair-wise).
• Tries to preserve the operator's preferred order.

When TOBT slips, the PDS updates and TSAT moves; an updated DPI carries the change to NMOC.

5. A-CDM in Adverse Conditions#

Degraded-mode procedures that keep TOBT/TSAT discipline working when capacity drops. Typical adverse cases:

• Low Visibility Procedures (LVP) — reduced runway throughput.
• De-icing operations — extra step in the turnround, often with a central pad and queue.
• Snow plan / runway closure for sweeping — periodic capacity loss.
• Capacity reduction by ATFM regulation — multiple CTOTs in force.
• Stand or apron unavailability — diversions of inbound traffic to remote stands.

The element matters because in good weather the discipline is easy; in bad weather the discipline is what prevents collapse.

6. Collaborative Management of Flight Updates / NOP Integration#

Sending DPI (Departure Planning Information) messages from the airport CDM platform to NMOC so the NOP holds the airport's own departure estimates instead of CFMU-computed ones. The DPI family:

• E-DPI (Early DPI) — first confirmation of the flight, sent typically around EOBT − 3 h or at first TOBT, replacing the network's internal estimate.
• T-DPI-t (Target DPI – target) — refined TOBT/TTOT before the PDS is built.
• T-DPI-s (Target DPI – sequenced) — sent once the flight is in the PDS and a TSAT has been issued; carries TSAT and TTOT.
• A-DPI (ATC DPI) — sent at start-up / off-block; locks AOBT and the final TTOT.
• C-DPI (Cancel DPI) — cancels a previously sent DPI (flight cancelled, long delay, returned to stand).
• X-DPI — de-suspension / additional update used in some implementations.

DPI exchange is what allows the NOP to reflect airport reality and what improves CTOT quality and slot adherence network-wide.

Putting the components together#

Information Sharing  --underpins-->  Milestones
                                    Milestones  --feed-->  PDS  --produces-->  TSAT
                                                        VTT  ---computes--->   TTOT
                                                                          DPI --to NMOC
Adverse Conditions   --modifies-->   all of the above

Each component on its own is useful but partial. The discipline emerges only when all six are in operation together.

A-CDM does not have "Blocks" in the ASBU sense as a property of the concept itself; instead, the EUROCONTROL Implementation Manual stages deployment as a sequence of implementation phases, and the ICAO GANP positions A-CDM as a two-Block thread (ACDM-B0 then ACDM-B1). This file describes both views.

ICAO GANP / ASBU view#

A-CDM is the ASBU thread ACDM. The Block layout is:

ACDM-B0 is a Block 0 module: the underlying SARPs (Annex 11 ATFM, Annex 14 aerodrome data), PANS (Doc 4444 Chapter 8 ATFM provisions), and Doc 9971 guidance were mature enough by 2013 that any State could deploy it. ACDM-B1 builds on SWIM-B0/B1, mature NOPS-B0/B1 (network operations), and DAIM-B0/B1 (digital aerodrome data).

EUROCONTROL implementation phases#

The EUROCONTROL Airport CDM Implementation Manual lays out a staged build of the six concept elements rather than a strict block model. Most non-EU airports connecting to NMOC follow the same staging.

Stage A — Foundation (Information Sharing)#

Theme. Build the shared situational picture and the partner governance.

• Sign the A-CDM Local Implementation Plan and CDM Operating Procedures.
• Deploy or extend the airport operations database (AODB).
• Connect aircraft operators, ground handlers, ATC, apron, and de-icing feeds.
• Publish data quality requirements per partner.
• Stand up the local A-CDM steering group / change board.

Exit criterion. All partners see the same flight, the same EOBT, the same stand allocation, in real time.

Stage B — Milestones Approach#

Theme. Activate the sixteen milestones and their event capture.

• Map each milestone event to the partner system that is the source of truth for it.
• Capture planned and actual times for every milestone.
• Configure deviation alerts (e.g. TOBT not confirmed by EOBT − 40 min, TSAT exceeded by N minutes).

Exit criterion. Every flight in the system has a complete, time- stamped milestone trail.

Stage C — Variable Taxi Time (VTT)#

Theme. Replace generic taxi assumptions with empirically derived, context-specific values.

• Build the historical taxi-time data set per stand × runway × time of day × configuration.
• Validate VTT tables against operational performance.
• Wire VTT into TSAT and TTOT calculations.

Exit criterion. TTOT accuracy is within target tolerance against ATOT for the majority of departures.

Stage D — Pre-Departure Sequence (PDS)#

Theme. Bring TOBT/TSAT discipline into the runway sequence.

• Tower deploys (or upgrades) DMAN with PDS function.
• ATC issues TSATs from TOBT inputs and updates PDS as TOBT changes.
• Operators / handlers manage TOBT proactively (no late, unannounced slips).

Exit criterion. Tower starts every departure from a TSAT-driven sequence; engine-on holding at the runway drops measurably.

Stage E — Adverse Conditions#

Theme. Make A-CDM robust under degraded modes (LVP, de-icing, snow, capacity reduction).

• Publish adverse-condition procedures: TOBT discipline under de-icing queue, LVP runway-rate, snow-plan capacity declarations.
• Drill the procedures with all partners.
• Adjust VTT and PDS rule-sets per condition.

Exit criterion. Predictability and slot adherence in adverse conditions remain within an acceptable margin of nominal.

Stage F — NM / NOP Integration (DPI)#

Theme. Send the airport's own departure picture to the network manager.

• Implement the DPI message family (E-DPI, T-DPI-t, T-DPI-s, A-DPI, C-DPI; X-DPI where used).
• Pass conformance testing with NMOC (or the regional flow entity).
• Reach NM A-CDM status — the airport's DPIs are accepted as the authoritative feed for the NOP.

Exit criterion. NMOC computes CTOTs against the airport's TTOT, not against generic estimates; CTOT quality and slot adherence improve.

Maturity levels in operation#

Once all six stages are live, a deployed A-CDM is typically described by three maturity bands:

• Initial A-CDM. Stages A–D operational, partner discipline still maturing, no DPI exchange yet.
• Full A-CDM (local). All six concept elements live locally; DPIs not yet exchanged with NM.
• Full A-CDM with NM integration ("NM A-CDM"). DPIs accepted by NMOC; the airport is a node in the NOP.

This last status is the one usually referenced when an airport is listed as "A-CDM airport" in the EUROCONTROL network.

Phase dependency principle#

As with ASBU blocks, later phases depend on earlier ones:

• VTT (Stage C) is meaningless without milestones (Stage B).
• PDS (Stage D) is unstable without VTT.
• Adverse-condition discipline (Stage E) collapses if PDS is unstable.
• DPI exchange (Stage F) carries garbage out if the upstream stages are not solid.

Trying to skip ahead to DPI exchange without stable TOBT/TSAT discipline produces NM-visible noise rather than NM-visible benefit, and is the single most common implementation failure mode.

A-CDM as a programme of work runs along several parallel pillars — feature areas that progress in parallel and depend on each other. Unlike ASBU Threads, which are global to the whole air-navigation system, the A-CDM pillars are internal to the concept and reflect how an airport team typically organises the work.

The pillars come in three families:

1. Operational pillars — what the partners do differently on the ramp, in the tower, and in the OCC.
2. Information pillars — how data flows between partners and outwards to the network.
3. Governance pillars — the agreements, procedures, and oversight that keep the discipline alive.

Operational pillars#

Milestone Tracking#

Definition, capture, and quality assurance of the sixteen turnround milestones (M1–M16). The pillar owns:

• Mapping each milestone to its source-of-truth system.
• Closing data gaps (e.g. handler systems that do not publish "boarding starts").
• Defining and tuning deviation alerts.

Milestone Tracking is the base layer for every other operational pillar. If milestones are noisy, TOBT discipline, PDS, and DPI all degrade.

TOBT Discipline (Operator / Handler)#

Operator-side ownership of TOBT:

• Maintain TOBT to reflect actual readiness, not contractual on-time performance.
• Update TOBT proactively when slippage is foreseen — do not wait for TSAT to expire.
• Apply the TOBT update window rules (typically: TOBT can move freely before the freeze horizon; after freeze, only operationally justified updates).

This is the single hardest cultural change in a new A-CDM deployment and the discipline that benefits most from incentives in the local A-CDM operating procedures.

Pre-Departure Sequence and TSAT (ATC)#

Tower-side ownership of TSAT:

• Build and continuously update the PDS from TOBTs, CTOTs, and runway configuration.
• Issue TSAT and re-issue when inputs change.
• Apply runway capacity declarations from the airport (especially under adverse conditions).

Surface and Stand Coordination#

The link to surface management (A-SMGCS Levels 3/4) and stand allocation:

• Stand changes are propagated to all partners.
• Routing on the manoeuvring area follows VTT assumptions.
• Conflicts between push/start and arrivals are resolved against the shared picture, not bilaterally on R/T.

De-icing and Adverse-Condition Operations#

A specialised operational pillar covering de-icing pad management, LVP operations, snow plan, and capacity reduction. The pillar maintains the adverse-condition rule-sets that Stage E of the implementation manual codifies (see blocks.md).

Information pillars#

Internal Information Sharing#

The airport-internal data layer:

• The airport operations database (AODB) and its feeds from each partner.
• Quality and timeliness rules per data element.
• Access rights per partner and per role.

Doc 8126 §1.5.1 grounds this as "quality-assured digital information" underpinning collaborative decisions; Doc 10199 (PANS-IM) supplies the information-service grammar (Set TOBT / Delete TOBT) that A-CDM implementations now adopt.

NM / NOP Integration (DPI / FUM)#

The outward data layer to the network:

• DPI messages out (E-DPI, T-DPI-t, T-DPI-s, A-DPI, C-DPI, X-DPI).
• Flight Update Messages (FUM) in — NMOC's view of the inbound flight (estimated landing times) used to anticipate turnround start.
• Conformance testing against NMOC interface specifications.

The pillar matures once the airport reaches NM A-CDM status (NMOC treats the airport's DPIs as the authoritative feed for the NOP).

SWIM-Enabled Partner Integration#

Later A-CDM blocks (ACDM-B1) replace point-to-point partner integrations with SWIM-based services. The pillar covers:

• Publishing A-CDM data as SWIM services per Doc 10199 (PANS-IM) service grammar.
• Subscribing to MET, AIM, and flow-management services from the same SWIM substrate.
• Identity, access, and quality-of-service management.

This is the bridge from ASBU ACDM-B0 to ACDM-B1 and beyond into total-airport-management designs.

Governance pillars#

Local A-CDM Steering Group#

The cross-partner board that owns:

• The Local Implementation Plan and the CDM Operating Procedures.
• Performance reviews against agreed KPIs.
• Change control on the milestone definitions, VTT tables, and adverse-condition rule-sets.

Agreements and Letters of Operation#

The contractual layer:

• A-CDM Letter of Agreement between the airport, ANSP, and operators.
• Service-level agreements with handlers covering TOBT-update responsibilities and reporting.
• Bilateral A-CDM agreements with the network manager for DPI exchange.

Performance Monitoring and Continuous Improvement#

The closing-the-loop pillar:

• Monthly / quarterly review of off-block punctuality, taxi-out time, TSAT-vs-AOBT variance, CTOT compliance, slot adherence.
• Root-cause analysis of TOBT misses.
• Feedback into VTT recalibration and operating procedure updates.

Cross-pillar dependencies#

• TSAT (operational) depends on TOBT discipline (operational) and Internal Information Sharing (information).
• DPI to NMOC (information) depends on PDS / TSAT (operational) being stable.
• SWIM partner integration (information) depends on DAIM and SWIM at the airport-information level.
• Adverse-conditions operations depend on the Steering Group (governance) having pre-agreed degraded-mode rule-sets.

The pillars cannot be advanced independently. The Implementation Manual calls this out explicitly: an airport cannot claim "A-CDM" if any one pillar is missing — particularly Milestone Tracking and Internal Information Sharing, which the others stand on.

What a "module" is in A-CDM#

Where ASBU has formal Modules (cells of Block × Thread), A-CDM is built from milestones and a small number of sub-processes (TOBT update, TSAT issue, DPI exchange, adverse-condition activation). Implementation work decomposes into these units; this file gives the common anatomy used to specify each one.

The same twelve-section template the GANP Portal uses for ASBU Modules maps cleanly onto an A-CDM milestone or sub-process. Use it as a checklist.

Anatomy of a milestone or sub-process#

1. Title and identifier#

Each milestone has a stable identifier (M1–M16). Sub-processes are typically identified by name (TOBT-Update, TSAT-Issue, DPI-Send, Adverse-Activate, etc.).

2. Operational improvement description#

What changes operationally when this milestone or sub-process is adopted, and what failure mode it removes from the legacy ad-hoc turnround.

3. Performance objective and applicable KPAs#

Which Key Performance Areas the unit improves: predictability, capacity, flight efficiency, environment, cost-effectiveness, safety. The KPA set comes from Doc 9854 / Doc 9883.

4. Procedure element#

The procedural changes required:

• Local A-CDM Operating Procedures (issued under the Local Implementation Plan).
• ATS coordination procedures per Doc 4444 (PANS-ATM), Chapter 8 — ATFM.
• Where CTOT phraseology is involved (start-up clearance against an ATFM slot), Doc 7030 (Regional SUPPs), §10.5: SAM, SRM, SLC, FLS, DES.

5. Technology element#

The systems that must be in place:

• Airport operations database (AODB).
• DMAN with PDS function (for TSAT).
• Handler / OCC systems publishing the relevant milestone events.
• NM interface gateway for DPI/FUM exchange.
• A-SMGCS (Levels 1–4 as scope dictates) for surface elements.

6. Human performance element#

Training and competency:

• Controller training on TSAT issue and PDS management.
• Ramp / handler training on TOBT discipline.
• Airline OCC training on DPI implications and ATFM impact.
• HMI design for the dashboards each role uses.

7. Standards basis#

The SARPs and PANS each unit relies on:

• Annex 11 (ATS) and Doc 4444 (PANS-ATM) Chapter 8 — ATFM provisions.
• Annex 14 Vol I, Attachment A, §22.2.1 and Doc 10066 (PANS-Aerodromes), §5.3.3.3 — aerodrome mapping data sets supporting CDM.
• Doc 8126 (AIM Manual), §1.5.1 — collaborative decision making discipline.
• Doc 10199 (PANS-IM) — information service grammar (Set TOBT / Delete TOBT).
• Doc 9971 (Manual on Collaborative ATFM) — flow-management context for the network-side interactions.

8. Enablers#

Infrastructure, regulatory, and institutional prerequisites — see enablers.md.

9. Dependencies#

Other milestones / sub-processes that must be operating first. Examples:

• M10 (TSAT) depends on M9 (TOBT) and on a working PDS.
• DPI-Send depends on stable TOBT/TSAT discipline upstream.
• Adverse-Activate depends on pre-agreed rule-sets and tested drills.

10. KPI linkage#

How the unit's effect is measured. KPIs are defined in performance_objectives.md.

11. Region applicability#

Most A-CDM elements are universally applicable, but some are tied to specific environments:

• DPI exchange with NMOC is European; APAC and MID airports use the regional flow entity (or no DPI exchange yet).
• De-icing pad procedures apply only at airports that de-ice.
• Snow-plan adverse-condition rules apply only at airports with a meaningful winter operation.

12. Implementation guidance#

Pointers to the EUROCONTROL Airport CDM Implementation Manual chapters, the EUROCONTROL Specification for A-CDM (EUROCONTROL-SPEC-0157), and the EUROCONTROL Network Manager DPI Implementation Guide.

Worked examples#

Example 1 — M9 TOBT Issued#

• Operational improvement. Replaces ad-hoc, late, often verbal notification of off-block readiness with a single time owned by the operator/handler, visible to all partners.
• KPAs. Predictability, capacity, cost-effectiveness, environment.
• Procedure. Handler / OCC publishes TOBT no later than EOBT − N minutes (per Local A-CDM Operating Procedures); TOBT update rules before and after freeze horizon.
• Technology. AODB or A-CDM platform with TOBT entry from handler and operator systems; alerts on TOBT-not-confirmed.
• Enablers. SLAs with handlers; training; partner agreement on freeze horizon.
• Dependencies. Internal Information Sharing live; M7 (in-block) and M8 (handling start) captured.
• KPIs. TOBT-on-time rate; mean TOBT update count per flight; TOBT-vs-AOBT variance.

Example 2 — M10 TSAT Issued#

• Operational improvement. Replaces a generic taxi-out plus runway- queue assumption with a deterministic, sequence-aware time issued by the tower, communicated to operator/handler via the shared picture.
• KPAs. Predictability, capacity, fuel efficiency.
• Procedure. PDS algorithm publishes TSAT from TOBT; TSAT honours CTOT, runway capacity, wake separation.
• Technology. DMAN with PDS function; CTOT feed from NMOC; runway configuration manager.
• Enablers. Controller training; VTT tables current; runway capacity declarations agreed.
• Dependencies. M9 (TOBT) stable; VTT calibrated.
• KPIs. TSAT-vs-AOBT variance; engine-on holding time at runway.

Example 3 — DPI-Send (sub-process)#

• Operational improvement. Replaces NMOC's internal estimate of the airport's TTOT with the airport's own estimate, improving CTOT quality and slot adherence network-wide.
• KPAs. Predictability, capacity (network), interoperability.
• Procedure. E-DPI sent at EOBT − 3 h or first TOBT; T-DPI-t before PDS build; T-DPI-s once TSAT issued; A-DPI at off-block; C-DPI on cancellation.
• Technology. NM interface gateway; conformance testing against EUROCONTROL Network Manager DPI Implementation Guide.
• Enablers. Bilateral agreement with network manager; certification / conformance testing; operations support.
• Dependencies. TOBT/TSAT discipline stable; M9 and M10 reliable.
• KPIs. DPI conformance rate; CTOT quality at the airport; ATFM-slot adherence.

How milestones become a deployment plan#

A local A-CDM deployment plan is produced by:

1. Listing the sixteen milestones and the four to six core sub-processes.
2. Sequencing them per the dependency rules above.
3. Mapping each to the responsible partner organisation, system change, and procedure update.
4. Agreeing the plan in the Local A-CDM Steering Group.
5. Reporting status into the regional plan (APAC Seamless ATM Plan, EUR LSSIP, MID ANS).

What an Enabler is#

An A-CDM Enabler is a supporting element without which the concept elements cannot deliver their intended benefit. Enablers are not themselves operational improvements; they are prerequisites. As with ASBU, A-CDM planning makes them explicit so an airport does not deploy the operational layer on a missing foundation.

Enablers fall into seven categories, mirroring the ASBU enabler taxonomy.

1. CNS / IT infrastructure#

The communications, networking, and IT substrate.

• Airport operations database (AODB) — the system of record for the flight, the stand, and the milestone events.
• A-CDM platform — the integration / portal layer that aggregates partner data, runs alerts, and drives partner dashboards.
• DMAN with Pre-Departure Sequence function — the tower system that computes and issues TSAT.
• Surface management (A-SMGCS Levels 1–4) — surveillance of stands, taxiways, and runways feeding the shared picture and runway-incursion protection (Annex 14 Vol I, Attachment A, §22.2.1 and Doc 10066, §5.3.3.3 require aerodrome mapping data sets accurate enough to support these applications).
• NM interface gateway — DPI/FUM exchange with NMOC or the regional flow entity.
• Partner connectivity — secure links to handler systems, airline OCC, de-icing operator, fuel system, customs, security, baggage and passenger systems.
• AIM data feeds — AIXM 5 aerodrome mapping data, electronic AIP, NOTAMs in machine-readable form (the DAIM thread).

2. Procedures#

Procedural changes anchored in ICAO PANS, regional supplementary procedures, and local operating documents.

• Doc 4444 — PANS-ATM, Chapter 8 — ATFM provisions consumed by A-CDM at the network boundary (CTOT delivery, slot allocation, suspension).
• Doc 10066 — PANS-Aerodromes, §5.3.3.3 — aerodrome mapping data sets in support of CDM and common situational awareness.
• Doc 7030 — Regional Supplementary Procedures, §10.5 — CTOT-related phraseology (SAM, SRM, SLC, FLS, DES) used when ATC issues start-up clearance against an ATFM slot.
• Doc 9971 — Manual on Collaborative ATFM — guidance for the collaborative ATFM processes that A-CDM feeds into.
• Doc 10199 — PANS-IM — information-service grammar (Set TOBT / Delete TOBT) for A-CDM data exchange.
• Local A-CDM Operating Procedures — issued under the Local Implementation Plan; they specify TOBT update rules, freeze horizon, TSAT issue, adverse-condition triggers, and DPI message timing.

3. Standards (SARPs)#

Annex provisions that underpin A-CDM:

• Annex 1 — Personnel Licensing. Controller endorsements (TWR/APP ratings) covering A-CDM-aware procedures.
• Annex 3 — Meteorological Service. MET inputs to LVP and adverse conditions.
• Annex 6 — Operation of Aircraft. Operator obligations for filed flight plan accuracy (EOBT) — the upstream commitment that A-CDM refines into TOBT.
• Annex 10 — Aeronautical Telecommunications. R/T phraseology and data-link standards used by ATC at the start-up and pushback interface.
• Annex 11 — Air Traffic Services. ATS provision, ATFM provisions, airspace classification; A-CDM is the airport-level discipline that the ATFM provisions presume.
• Annex 14 — Aerodromes, Vol I, Attachment A, §22.2.1 — aerodrome mapping data sets supporting CDM, common situational awareness, and aerodrome guidance applications including A-SMGCS Levels 1–4.
• Annex 15 — Aeronautical Information Services. Quality-managed digital data sets feeding the shared picture.
• Annex 19 — Safety Management. SMS integration of the A-CDM workflow and its degraded modes.

4. Avionics and fleet equipage#

A-CDM is largely a ground concept, so avionics demand is light, but some elements matter:

• Data link (CPDLC) — increasingly used for digital pre-departure clearance, where it can shorten the M13 → M14 leg.
• ACARS — used by airline OCC systems to update TOBT and receive TSAT.
• No new mandatory avionics are imposed by A-CDM itself; benefits accrue from existing equipage.

5. Regulatory framework#

• State approval for the local A-CDM scheme as a procedural ATS arrangement under Annex 11.
• Safety oversight under Annex 19 / State Safety Programme — the A-CDM platform and its degraded-mode procedures form part of the ATS safety case.
• Cybersecurity regulation for the A-CDM platform and its NM interface (the platform aggregates commercially sensitive operational data across organisations).
• Charging / cost-recovery policy (Doc 9082, Doc 9587) to fund the ATM-side investment proportionate to its benefit.
• Data-sharing legal basis between partners (especially across airline-handler-airport boundaries).

6. Human resources and training#

• Controllers — TSAT issue, PDS management, adverse-condition procedures, CTOT phraseology (Doc 7030 §10.5).
• Ramp / handler staff — TOBT discipline, milestone capture responsibilities.
• Airline OCC — TOBT update workflow and ATFM impact.
• Apron control — push/start coordination against TSAT.
• AIM officers — aerodrome mapping data quality (the data layer that surface and CDM applications stand on).
• A-CDM platform engineers / operations — interface monitoring, DPI conformance, alert tuning.

7. Institutional and inter-organisational#

• Local A-CDM Steering Group — cross-partner board owning the Local Implementation Plan.
• A-CDM Letter of Agreement between airport, ANSP, and operators.
• Service-level agreements with ground handlers covering TOBT responsibilities, milestone reporting, and minimum data quality.
• Bilateral agreement with the network manager (NMOC for EUROCONTROL airspace; the regional flow entity elsewhere) for DPI exchange.
• Regional planning forum endorsement — APANPIRG (APAC), MIDANPIRG (MID), EANPG (EUR), GREPECAS (CAR/SAM) endorsing the State's A-CDM rollout in the regional implementation plan.

How enablers are managed in practice#

The Local A-CDM Steering Group typically maintains an enabler matrix — one row per enabler, one column per status indicator (in-place, in-progress, blocked) — and reviews it at every meeting. An airport is considered to have implemented a concept element only when all of its declared enablers are also in place: deploying the headline tool without the procedure, training, agreement, or data quality behind it is the most common implementation failure mode.

This is why an A-CDM rollout is much more than installing a platform: an airport that buys an A-CDM portal without re-writing its operating procedures, training all partners, and agreeing a TOBT discipline with the handlers will not see the predicted benefit.

The performance lens of A-CDM#

A-CDM is a performance-based concept. Every component (information sharing, milestones, VTT, PDS, adverse conditions, NOP integration) is justified by a measurable improvement in airport and network performance. The terminology comes from the Global ATM Operational Concept (Doc 9854) and the Manual on Global Performance of the Air Navigation System (Doc 9883).

The chain is:

KPA  --(measured by)-->  KPI  <--(targeted by)--  Performance Objective  --(achieved by)-->  A-CDM component / milestone

Key Performance Areas (KPAs) most relevant to A-CDM#

Of the eleven KPAs from Doc 9854 / Doc 9883, A-CDM primarily affects:

1. Predictability — variance between planned and actual times. This is the headline KPA; A-CDM's whole point is to compress the variance between EOBT, TOBT, TSAT, AOBT, TTOT, and ATOT.
2. Capacity — runway and surface throughput. A-CDM raises throughput by removing slack from taxi-out and start-up, and by feeding ATFM with truthful estimates that allow tighter regulation.
3. Environmental impact — fuel burn and CO2. Engines burn less when the aircraft pushes when the runway is available; A-CDM cuts engine-on holding at the runway and engine-off slack at the stand.
4. Cost-effectiveness — unit cost of ATM service per movement. A-CDM raises throughput without raising the controller workforce and reduces airline delay cost.
5. Flight efficiency — within the airport boundary, taxi-out efficiency and the absence of avoidable holding.
6. Safety — secondary but real: stable runway sequences and clear surface plans reduce runway-incursion risk and mis-coordination.
7. Interoperability — A-CDM is the airport-side interface to the network; its DPI exchange is the interoperable contract with NMOC or the regional flow entity.

Performance Objectives (illustrative)#

The following Performance Objectives, expressed in the GANP catalogue style, are the ones an A-CDM business case typically commits to:

• PO — Improve airport departure predictability. Measured by standard deviation of AOBT vs. TOBT and of ATOT vs. TTOT. Delivered by Information Sharing, Milestones, VTT, PDS.
• PO — Reduce engine-on holding at the runway. Measured by mean and 95th-percentile time from M14 (start-up approved) to M16 (take-off). Delivered by PDS / TSAT discipline and CTOT-aware sequencing.
• PO — Improve ATFM slot adherence at the airport. Measured by CTOT compliance rate (within −5 / +10 minutes) and ATFM-slot misses per 1000 movements. Delivered by NM integration (DPI) and Adverse- Conditions discipline.
• PO — Reduce runway-throughput loss in adverse conditions. Measured by movements per hour delta between nominal and LVP / snow / de-icing operations. Delivered by Adverse-Conditions procedures.
• PO — Reduce departure fuel burn / CO2 per movement. Measured by fuel and CO2 per departure attributable to ground time and engine-on holding. Delivered by VTT, PDS, Adverse-Conditions.
• PO — Improve resilience of the airport-network handover. Measured by NOP/airport TTOT alignment and CTOT update churn. Delivered by NM Integration (DPI/FUM).

Key Performance Indicators (KPIs)#

Quantitative measures that an A-CDM Steering Group and the regional authority typically track. EUROCONTROL publishes detailed definitions for European A-CDM airports; APAC, MID, and other regions adopt similar metrics.

Predictability KPIs#

• TOBT-vs-AOBT variance (mean and standard deviation).
• TSAT-vs-AOBT variance (the TSAT compliance metric).
• TTOT-vs-ATOT variance.
• TOBT update count per flight.
• TOBT-on-time rate (TOBT confirmed by EOBT − N minutes).

Capacity KPIs#

• Movements per hour at the runway in nominal and adverse conditions.
• Push-back rate (off-blocks per 15-minute window).
• Stand utilisation.

Flight efficiency / environmental KPIs#

• Mean taxi-out time, with and without A-CDM compared.
• Engine-on holding time at the runway (M14 to M16 vs. nominal).
• Fuel and CO2 per departure attributable to ground delay.
• Excess holding due to slot misalignment.

Network / ATFM KPIs#

• CTOT adherence rate.
• ATFM slot misses per 1000 movements.
• Mean ATFM departure delay.
• DPI conformance rate (DPIs accepted by NMOC vs. rejected).
• NOP/airport TTOT alignment (delta between airport TTOT and NOP TTOT).

Safety KPIs#

• Runway-incursion rate per movement.
• Loss-of-coordination events between tower and apron.

Cost-effectiveness KPIs#

• Airline delay cost per movement.
• Unit cost of ATS at the aerodrome.
• Productivity of the runway (movements per controller-hour at the position).

How A-CDM performance is reported#

• Locally — Local A-CDM Steering Group reports monthly / quarterly.
• Regionally
  • Europe — EUROCONTROL Performance Review Body and the LSSIP cycle; CFMU/NMOC publishes A-CDM airport performance.
  • APAC — APANPIRG performance reporting and the Seamless ATM Plan.
  • MID — MIDANPIRG and the MID Air Navigation Strategy.
• Globally — A-CDM appears in ICAO ASBU implementation monitoring reports under thread ACDM (modules ACDM-B0, ACDM-B1).

Why this matters for planning#

Tying every A-CDM component to a Performance Objective and a KPI keeps the deployment honest. It forces the question "what measurable problem does this fix?" during the business case (Doc 9587 explicitly requires business-case justification for ASBU funding, and A-CDM is funded under ASBU ACDM-B0/ACDM-B1). It gives the Steering Group the language to ask whether the deployed capability is delivering the promised benefit and to recalibrate VTT, PDS rule-sets, and adverse-condition procedures when KPIs slip.

Three timelines to keep distinct#

When discussing A-CDM "dates", separate three things:

1. EUROCONTROL Implementation Manual edition timeline — when the de-facto detailed reference for A-CDM was published / amended.
2. ICAO document timeline — when the supporting ICAO PANS, manuals, and Annexes integrated CDM and A-CDM language.
3. Deployment timeline — when individual airports went live as "A-CDM airports" or reached NM A-CDM (DPI exchange with NMOC).

A national or airport-level rollout plan is a fourth, local timeline expressed against the EUROCONTROL Manual phases (see blocks.md) and, for ASBU reporting, against the ACDM-B0 / ACDM-B1 Block availability windows.

EUROCONTROL Airport CDM Implementation Manual#

The de-facto reference is the current edition of the EUROCONTROL Airport CDM Implementation Manual, published alongside the EUROCONTROL Specification for A-CDM (EUROCONTROL-SPEC-0157) and the EUROCONTROL Network Manager DPI Implementation Guide.

ICAO document timeline#

The two key inflection points in the ICAO timeline are the publication of Doc 9971 (which supplied the network-side guidance that A-CDM presumes) and the publication of Doc 10199 PANS-IM (which gave A-CDM data exchange a formal information-service grammar).

ICAO GANP / ASBU timeline for A-CDM#

A-CDM is the ASBU thread ACDM. Block availability is:

ACDM-B0 ........ from 2013   (Airport CDM)
ACDM-B1 ........ from 2019   (Full A-CDM-to-network-manager integration)

These are the dates from which the SARPs, PANS, and EUROCONTROL manuals were mature enough that any State could implement the module — not deadlines for States. A State that implements ACDM-B0 in 2026 has still implemented ACDM-B0.

Deployment timeline (illustrative)#

The actual airport-by-airport rollout is European-led and EUROCONTROL- maintained. Indicative milestones — verify current status against the EUROCONTROL A-CDM page (https://www.eurocontrol.int/concept/airport-collaborative-decision-making):

• 2010 — Munich (MUC) becomes the first NM A-CDM airport (DPI exchange with NMOC).
• early 2010s — Brussels, Frankfurt, Paris CDG, Zurich, Helsinki, London Heathrow follow.
• mid 2010s — Madrid, Rome, Amsterdam, Vienna, Oslo, Copenhagen, Prague reach NM A-CDM status; rollout extends to more secondary hubs.
• late 2010s / 2020s — broader European rollout; APAC, MID, and other regions begin local A-CDM deployments without (yet) DPI exchange to NMOC, often using regional flow entities as the network endpoint.

The number of European NM A-CDM airports has grown steadily through the 2010s and 2020s; the live count is on the EUROCONTROL A-CDM page.

Where Pakistan / APAC sit on this timeline#

Indicative regional context (verify current status against the latest APANPIRG and ICAO APAC Implementation Plan documents — these change annually):

• Concept-level adoption — A-CDM is on the APAC Seamless ATM Plan as a Block 0 capability.
• Major hubs — initial A-CDM deployments at the largest hubs (often staged at Initial A-CDM and Full A-CDM (local) maturity bands).
• NM A-CDM equivalent — APAC airports use the regional flow entity rather than NMOC; full DPI-equivalent integration is staged on the regional roadmap.
• Secondary airports — implementation behind the Block 0 baseline; candidates for the next planning cycle.

How to read a date in an A-CDM document#

When an A-CDM document uses a date, check which kind of date it is:

• "ACDM-B0 from 2013" — Block availability date (global notional earliest).
• "Munich NM A-CDM 2010" — local deployment go-live.
• "Manual edition 20xx" — EUROCONTROL document publication date.
• "Performance target by 20xx" — regional or airport performance ambition.

Mixing these up leads to false claims that an airport is "behind" or "ahead" on A-CDM, when in fact the only meaningful measure is the airport's own Local Implementation Plan against its declared maturity-band milestones.

Primary ICAO documents#

• Doc 9971 — Manual on Collaborative Air Traffic Flow Management. ICAO's authoritative guidance for the collaborative ATFM environment that A-CDM feeds with departure estimates and consumes in the form of CTOTs. Referenced from Doc 4444 (PANS-ATM), Chapter 8 — ATFM.
• Doc 4444 — PANS-ATM, Chapter 8 — ATFM. Air traffic services procedures for flow management; the procedural envelope inside which A-CDM operates at the airport / network boundary.
• Doc 8126 — Aeronautical Information Services Manual, §1.5.1 — defines CDM as taking ATM decisions collaboratively on quality-assured digital information rather than in isolation; lists CDM among the SWIM-enabled ATM applications served by AIM.
• Doc 10199 — PANS-IM (Procedures for Air Navigation Services — Information Management). Uses Set TOBT / Delete TOBT as the worked example of an information service, expressly tied to the A-CDM concept and its A-CDM Partners (operators, ground handlers).
• Doc 10066 — PANS-Aerodromes / PANS-AIM, §5.3.3.3 — aerodrome mapping data sets intended to support CDM, common situational awareness, and aerodrome guidance applications; basis for AMDBs and A-SMGCS Levels 1–4.
• Doc 7030 — Regional Supplementary Procedures, §10.5 — ATFM phraseology for CTOT delivery (SAM), revision (SRM), cancellation (SLC), flight suspension (FLS) and de-suspension (DES); the radiotelephony layer used by the tower when issuing TSAT/CTOT-driven start-up clearance.
• Doc 9854 — Global Air Traffic Management Operational Concept. Source of the Key Performance Areas referenced in the A-CDM performance lens.
• Doc 9883 — Manual on Global Performance of the Air Navigation System. Performance-management methodology (KPAs, KPIs, Performance Objectives) used to justify and measure A-CDM benefit.
• Doc 9750 — Global Air Navigation Plan (GANP). Carries A-CDM as the ASBU thread ACDM (modules ACDM-B0 and ACDM-B1).
• Doc 9082 — Policies on Charges for Airports and Air Navigation Services. Charging-policy basis for funding ATM modernisation, including A-CDM.
• Doc 9587 — Policy and Guidance Material on the Economic Regulation of International Air Transport. Invokes the global plan for ASBUs as the reference for infrastructure financing and business-case justification, including for A-CDM under thread ACDM.

ICAO Annexes most touched by A-CDM#

• Annex 11 — Air Traffic Services. ATS provision and ATFM provisions; the airspace and procedural backdrop A-CDM sits in.
• Annex 14 — Aerodromes, Vol I, Attachment A, §22.2.1 — aerodrome mapping data with appropriate accuracy supports collaborative decision-making, common situational awareness, and aerodrome guidance applications (incl. A-SMGCS Levels 1–4).
• Annex 15 — Aeronautical Information Services. Quality-managed digital data sets feeding the shared situational picture.
• Annex 19 — Safety Management. SMS framing of the A-CDM workflow and its degraded modes.
• Annex 1, Annex 6, Annex 10 — adjacent: licensing endorsements, operator obligations, R/T phraseology.

EUROCONTROL — primary practical references#

• EUROCONTROL Airport CDM Implementation Manual (current edition). The de-facto detailed reference for European implementations and for most non-EU airports that connect to NMOC. Defines the six concept elements, sixteen milestones, TOBT/TSAT discipline, VTT, PDS, adverse-conditions procedures, and the DPI message set (authoritative source — not in local library).
• EUROCONTROL Specification for Airport CDM (EUROCONTROL-SPEC-0157). Normative specification underpinning the Implementation Manual (authoritative source — not in local library).
• EUROCONTROL Network Manager DPI Implementation Guide. Message formats and timing for E-DPI, T-DPI-t, T-DPI-s, A-DPI, C-DPI, X-DPI exchanged with NMOC (authoritative source — not in local library).
• EUROCONTROL A-CDM concept page: https://www.eurocontrol.int/concept/airport-collaborative-decision-making
• EUROCONTROL Network Manager Operations Centre (NMOC): https://www.eurocontrol.int/network-manager

Live / authoritative ICAO sources#

• ICAO GANP Portal — https://ganpportal.icao.int/ — live home of the ASBU framework. The ACDM thread and modules ACDM-B0 / ACDM-B1 are maintained here.
• ASBU Threads catalogue: https://ganpportal.icao.int/asbu/thread
• ASBU Performance Objectives catalogue: https://www4.icao.int/ganpportal/asbu/performanceobjective
• ICAO GANP overview page: https://www.icao.int/global-air-navigation-plan-ganp

Regional implementation references#

• APAC Seamless ATM Plan (ICAO Asia/Pacific Regional Office). APAC realisation of the ASBU framework; A-CDM is included as a Block 0 capability and is monitored by APANPIRG.
• MID Air Navigation Strategy (ICAO MID Regional Office). MID realisation; monitored by MIDANPIRG.
• European ATM Master Plan (SESAR JU). EU-level integration of A-CDM into the broader ATM modernisation roadmap.
• EUROCONTROL LSSIP cycle — annual State reporting against ICAO ASBU and the European ATM Master Plan, including A-CDM deployment and NM A-CDM status.

Industry / training material#

• EUROCONTROL Airport CDM training resources (issued alongside the Implementation Manual).
• IATA / ACI training on A-CDM and total-airport-management — authoritative industry training (authoritative source — not in local library).