A-CDM General

General

A-CDM is short for Airport Collaborative Decision Making. It is a concept that ensures minimal delays and optimal efficiency by making operations more predictable for all parties involved. There are over 50 airports that implement A-CDM procedures in the real world, with more than 30 located in Europe. It works by allotting departure times to all departing aircraft, taking the airport's current capacity into account, which are calculated backwards to times for pushback and startup approvals. 

On Vatsim, this A-CDM process can be simulated using the CDM plugin, although some aspects of the process are simplified for simulation purposes. Besides the airport flow control to reduce delay at the holding points, the CDM plugin is also connected to the ATFCM process of Vatsim, thus enabling network-wide flow-control management. 

Usage

On Vatsim, within the EDWW FIR, the A-CDM process will be used at the following airports:

• Berlin-Brandenburg (BER/EDDB)
• Hamburg (HAM/EDDH)

ATC should always use the A-CDM procedures at EDDB and EDDH as long workload permits. The use of the A-CDM process is mandatory during (weekly) events. 

No matter if using the A-CDM process or not, ATC shall always adhere to the CTOTs (if present). 

A-CDM Process explained

The A-CDM process is explained here.

Abbreviations

Abbreviation	Time	Description
EOBT	Estimated Off-Block Time	Off-Block Time filed in the flight plan (e.g. from SimBrief).
TOBT	Target Off-Block Time	Time when the outbound is actually ready and would like to go off-block (submitted by the pilot via the VDGS website)
TSAT	Target Startup Approval Time	Time where the outbound is allowed to go off-block (+/- 5 minutes).
TTOT	Target Take-Off Time	Take-Off time based on the airport capacity. Outbounds do not have to stick to that time! Departure before and after is possible without any timeframe.
CTOT	Calculated Take-Off Time	Take-off time where traffic needs to depart within -5 to +10 minutes. Adhering to this time frame is mandatory.  Reason: limited enroute or arrival aerodrome capacity.