CDM Guide
What is CDM?
CDM (Collaborative Decision Making), manages demand and capacity across the network by coordinating departure slots, regulating outbound flow rates, and adjusting traffic patterns to prevent sector or airport overload. By providing a structured approach to traffic sequencing and delay management, CDM ensures smoother operations and more consistent handling during high-traffic conditions and major events.
Definitions
| Abbreviation | Description |
|---|---|
EOBT |
Estimated off block time |
TOBT |
Target off block time |
TSAT |
Target Start-Up Approval Time |
TSAC |
Target Start-Up Approval Communicated |
ASAT |
Actual Start-Up Approval Time |
ASRT |
Actual Start-Up Request Time |
TTOT |
Target Take Off Time |
CTOT |
Calculated Take Off Time |
Activating CDM
-
The plugin is split into 2 roles, "master" and "slave". The "master" should be the lowest ATC position, usually delivery.
When CDM is in use, an aerodrome should always have master, however only 1 master per aerodrome is permitted. Controllers may be the master at 2 airports if covering topdown, simply use the command below.
.cdm master {airport}should be used to become the master of the selected aerodrome. -
Using the CDM Master Panel, click on the aerodrome that you are opening (if you are controlling TMA and above, you are able to click multiple aerodromes) and wait until the aerodrome turns green. This indicates that this aerodrome is active with CDM.
Controller Change
During a controller handover, the current master (old controller) will change to a slave using .cdm slave {airport}, the new controller will then use the .cdm master {airport} command to become the new master. Once the new master has done this, the new controller will also need to run the .cdm resetmaster {airport} command.
Commands
| Command | Description |
|---|---|
.cdm resetmaster {airport} |
Resets the master for the new controller |
.cdm refresh |
Force the refresh phase to do it now. |
.cdm master {airport} |
Become the master of the selected airport. |
.cdm slave {airport} |
Turn back to slave of the selected airport. |
.cdm customdelay {airport}/{runway} {time-start} |
Moves all TSATs for the selected airport and runway. Use time 9999 to remove the delay. |
.cdm lvo |
Toggle LVP's on or off. |
.cdm recover {airport} |
In case of CTD (crashed to desktop), it tries to recover the latest time status backed up in the server. |
.cdm help |
Sends a message with the available commands. |
Functions and Colours
TOBT
If there is no existing TOBT, to add a TOBT, click on the column of the aircraft to set the current time as the TOBT.
| Colour | |
|---|---|
 LIGHT GREEN |
Before TOBT -5. |
 DARK GREEN |
TOBT -5 to -2 |
 YELLOW |
TOBT -1 |
TSAT
TSAT is defined as the TTOT minus the taxi time.
| Colour | |
|---|---|
LIGHT GREEN |
TOBT -35 to TSAT -5 |
DARK GREEN |
TSAT -5 to +5 |
YELLOW |
TSAT +5 to +6 |
CTOT
Shows the aircraft's CTOT
| Colour | |
|---|---|
 GREEN |
CDM Server CTOT |
 ORANGE |
Manual/Event CTOT |
 RED |
Flow/CAD CTOT |
NET
Shows the status from the CDM Network
| Colour | |
|---|---|
 REA |
Sends a REA message |
 PRIO |
Sets aircraft to top priority |
 SUSP |
When an aircraft's flightplan is suspended |
Usage
Delivery (DEL)
When CDM is in use, pilot's should call for clearance as normal, however DEL should inform the pilot of their TSAT.
Phraseology
UAE101, readback correct, QNH 1001 information A is current, TSAT 1203
When the pilot calls for start, the master should left click the TOBT column to generate timings (if not already there).
If the TSAT of the aircraft is ±5 minutes, shown in a DARK GREEN colour, then the aircraft should be handed off to GMC.
Phraseology
UAE101, hold position, contact ground 118.350
If the aircraft calls prior to the ±5 minute window, shown in a LIGHT GREEN colour, then the aircraft should be told to hold position and a TSAT should be passed on.
Phraseology
UAE101, TSAT 1203, hold position
Warning
When handing off from DEL to GMC, DEL should set the status of the aircraft to "FREQ".
Missed Slot
If the aircraft is not marked with "FREQ" before TSAT +6, CDM will determine the aircraft as suspended shown by SUSP in the NET column. When the aircraft calls ready for start the process is to be as normal where we left click the TOBT column to regenerate timings (as shown above).
Ground Movement Control (GMC)
When an aircraft calls for start, GMC should confirm that the TSAT is within ±5 minutes, shown DARK GREEN colour, before giving push and start.
Tower (AIR)
The AIR controller should make use of the TTOT/CTOT timings to determine the departure order of aircraft.
Pilot Submitted TOBT
Pilots are able to submit their own slot (TOBT) time through vats.im/vdgs. Through this system, pilots are able to manually input their TOBT and view their TTOT/CTOT among other information.
Frequently Asked Questions
What is the difference between TOBT and TSAT?
TOBT is the time the pilot would like to push without delays or traffic taken into consideration. TSAT includes all of this, the time the pilot would like to push added with delays, SID intervals as well as traffic around the Gulf.
Does white mean they have pushed on time?
If there TOBT/TSAT is showing white, it just means that they have pushed regardless of whether it was on time or not.
Do pilots NEED to submit their TOBT via the link?
No. If traffic at the aerodrome is light and it won’t cause any delays, you can manage this manually. When the pilot requests pushback, simply follow standard procedures, left-click the TOBT column to input their timings, and approve the pushback.