# What is CDM

CDM is a modern tool helping us to manage traffic flow, both in and out of Copenhagen but also to ensure capacity is not breached other places. Likewise it is used by other airports to modulate traffic flow to help our sectors

<p class="callout danger">CDM is MANDATORY for <span style="text-decoration: underline;">**ALL** </span>online controllers to different extents!</p>

- <p class="callout success">**ATFCM** is management of CTOTs as is mandatory for ALL controllers regardless of position as long as traffic load allows. This is discussed under "Simplified CDM Procedures"</p>
- <p class="callout success">**A-CDM** is management of TSAT for sequencing within the airports, and is mandatory for TWR/GND controllers to the extent feasable. This is discussed under "Expanded CDM Procedures"</p>
- <p class="callout info">CDM Module should always be running regardless</p>

<details id="bkmrk-abbriviations-for-cd"><summary>Abbreviations and Explanations</summary>

CDM: **Collaborative Decision Making**: patent term concerning flow restriction and planning to ensure appropriate ATC capacity during all phases of flight

ATFCM: **Air Traffic Flow Control Management:** Tool to modulate flights based on sector capacity by use of CTOTs to modulate traffic limitation around Europe.

A-CDM: **Airport-Collaborative Decision Making**: local airport flow regulations based on turnaround and TOBTs to ensure planes taxi and take off in a manner avoiding congestion

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EOBT : **Estimated off block time**: Time filed by the flightplan as planned start up time

TOBT: **Target off block time:** Time filed by the pilot after entering airplane as proposed start up time

TSAT: **Target Start Up Approval Time:** System created time for start up approval to comply with CDM/ATFCM

ASRT: **Requested Start Up Time:** Time pilot has requested start up, to search for earlier TSAts

CTOT: **Calculated Takeoff Time:** Time the pilot should take of at +10/-5 min, to comply with ATFCM.

</details>## What does it all mean?

Quick Breakdown for the basic rules

**EOBT** is always filed as part of the flight plan

**TOBT** is filed and changed during the boarding as predicted ready time may be changed back and forth. Pilot can freely choose this time. It is essentially a "Fine Tuning" of EOBT. A controller may also set this time.

**TSAT** is the time the CDM has targeted the pilot to start up on. This is based on

- 40 slots pr. hour meaning a takeoff time every 90 seconds
- Taxi time to the runway
- Making extra separation between two identical SIDs
- Finding a slot - taxi time which is as close as possible to the pilot filed TOBT.

**ASRT** is purely a marker you use to remind yourself pilot has requested start-up

**ASAT** is the time he has been given startup which is also in a way a marker.

<p class="callout warning">Pilots **KNOW** their TOBT (it is filed by them)</p>

<p class="callout warning">Pilots DO **NOT** know their TSAT (It is constantly changing and is calculated by the system)</p>

## What to expect from Pilots

1. Pilot have a off block time or EOBT. <span style="text-decoration: underline;">**This is filed with the flightplan**</span>
2. TOBT is automatically calculated and will initially be identical to the EOBT
3. Pilots will access "vats.im/vgds" to "Confirm" their off block time. This should be done by pilots who want to avoid extensive delay, but is not mandatory

[![image.png](https://wiki.vatsim-scandinavia.org/uploads/images/gallery/2025-12/scaled-1680-/image.png)](https://wiki.vatsim-scandinavia.org/uploads/images/gallery/2025-12/image.png)

<p class="callout info">Pilots shall call within +/- 5 minutes of their **TOBT** (the one they know)</p>

<p class="callout danger">Start-up shall only be granted within +/- 5 minutes of the **TSAT** (the calculated one) </p>