The Civil Aviation Authority of Thailand
Aeronautical Information Service Department
333/105 Lak Si Plaza, Khamphaeng Phet 6 Rd.
Talat Bang Khen, Lak Si, Bangkok 10210, Thailand

Tel: +662 568 8831

Fax: +662 576 1903




AIP Supplement for Thailand


A 40/23

Effective from 02 NOV 2023

to 31 OCT 2024

Published on 21 SEP 2023



This section supplements the following portion(s) of the AIP: AD

1.1  With effect from 2 November 2023 to 31 October 2024. An implementation of A-CDM at Don Mueang International Airport aims to optimize airport operations by sharing accurate and timely information among airport partners via iDEP system. It also improves pre-departure sequence, which is the main primary objective and the starting point of Don Mueang A-CDM. The process can help balance the number of flights with an ability to handle, both under normal situation and under any occurrence requiring co-decision making.

1.2  The purpose of this AIP supplement is to provide information of Don Mueang A-CDM procedures, and to detail the operation plan and the action required by Aircraft Operator (AO), Ground Handler (GH), Pilots and Air Traffic Controller (ATC).


2.1  Target Off-Block Time (TOBT) - The time that an Aircraft Operator (AO) or Ground Handler (GH) estimates that an aircraft will be ready, all doors closed, boarding bridge removed, pushback vehicle available and ready to start-up and push back immediately upon reception of clearance from the Aerodrome Control Tower (TWR).

2.2  Target Start-Up Approval Time (TSAT) - The time provided by ATC taking into account TOBT, CTOT and/or the traffic situation that an aircraft can expect start-up / push back approval.

2.3  Calculated Take-Off Time (CTOT) - A time calculated and issued by the appropriate Central Management unit, as a result of tactical slot allocation, at which a flight is expected to become airborne.


3.1  The objectives of A-CDM operation are as follows:

3.1.1  To increase efficiency of Pre-departure sequence for flight depart from Don Mueang International Airport by applying TOBT and TSAT.

3.1.2  To allow Aircraft Operator (AO)/Ground Handler (GH) to be familiar with how to notify TOBT and TSAT to pilots.

3.1.3  To verify TSAT issuance by iDEP system and to assess accuracy of TSAT.

3.2  All Departure flights are required to participate in the A-CDM operation.

3.3  Aircraft Operator (AO) / Ground Handler (GH) are to follow A-CDM TOBT procedures, TSAT procedures and Pilots/ATC are to follow start-up and push back procedures.


4.1  Don Mueang A-CDM Procedure Overview

The chart below describes the simple overview of the A-CDM process at Don Mueang International Airport from the time that airlines input the TOBT to the time that aircraft is airborne. It includes the responsibilities and procedures in brief, as described below:

4.2  Target Off-Block Time (TOBT) Procedures

4.2.1  General

The TOBT is the essential contribution of airlines to the A-CDM process which establishes the Pre-Departure Sequence taking into account operators preferences and operational constraints. Airlines or person responsible for the TOBT are required to access and manually input the TOBT into the iDEP system in order that the start-up approval time (TSAT) can be expected.

4.2.2  Person Responsible for TOBT

Airline operator (AO) is responsible for the input of and adherence to the TOBT. However, AO may prefer to delegate this function to ground handler (GH). It is the responsibility of the AO/GH to communicate and ensure that the pilot of a flight has the correct TOBT and TSAT prior to requesting ATC clearance.

AO need to ensure that a timely, accurate and stable TOBT is provided. If it becomes obvious that the TOBT cannot be respected, it shall be updated by the person responsible for the TOBT as early as possible.

4.2.3  TOBT Input and Revision

The following has to be taken into account for the input and/or revision of the TOBT:

  1. The first TOBT can be input at 120 minutes (2 hours) prior to EOBT.

  2. A TOBT input must be at least the present time.

  3. The TOBT revision can be made as often as desired until the TSAT has been issued (40 minutes prior to TOBT).

  4. After the TSAT has been issued, the TOBT can only be revised not more than 5 times to ensure a stable operation.

  5. New TOBT must differ by at least 5 minutes (+/-5 minutes) from the latest input TOBT to protect a stable Pre-Departure Sequence.

4.2.4  Flights with Calculated Take-Off Time (CTOT)

Flights with CTOT will usually take priority when calculating TSATs in order to minimize potential CTOT delay.

4.2.5  TOBT Deletion

  1. TOBT can be deleted by users with permission to input/revise the TOBT.

  2. If the TOBT is deleted, the TSAT is automatically deleted.

  3. The TOBT has to be deleted in the following cases:

    1. TOBT is unknown (e.g. technical problems with the aircraft), or

    2. The permitted number of TOBT revision (5 times) after the generation of the TSAT has been exceeded.

  4. If a new TOBT is known, the process shall continue and the person responsible for the TOBT has to enter a new TOBT.

4.2.6  TOBT Reporting Channels

The TOBT is reported or updated by the following ways:

  1. iDEP Web-based Application (

  2. SMS via digital trunked radio system

  3. Mobile Application

4.3  Target Start-Up Approval Time (TSAT) Procedures

4.3.1  General

The TSAT is the target time for start-up approval calculated by iDEP system based on the TOBT input from the airlines and operational constraints. The TSAT is calculated based on the following key parameters:

  1. Target Off-Block Time (TOBT)

  2. Calculated Take-Off Time (CTOT)

  3. Operational Capacity

  4. Variable Taxi Time (VTT)

  5. Parking Stand

  6. Departure Runway

4.3.2  TSAT Distribution  The TSAT is displayed/distributed 40 minutes prior to the TOBT.  After TSAT has been distributed, the TOBT can only be revised not more than 5 times to ensure a stable sequence and CTOT allocation.  Subsequent TOBT revision triggers a recalculation of TSAT. It should therefore be noted that an incorrect TOBT leads to disadvantages for further sequencing and/or CTOT allocation of regulated flights.  The TSAT may not be final and can be revised due to air traffic management.

4.3.3  TSAT Reporting Channels  The TSAT will be issued to airlines or person responsible for TOBT via the same reporting channels as the TOBT:

  1. iDEP Web-based Application (

  2. SMS via digital trunked radio system

  3. Mobile Application  The AO/GH is responsible for updating and ensuring that the pilot of a flight has the correct TOBT and TSAT prior to requesting ATC clearance.

4.4  Start-Up and Push Back Procedures

4.4.1  General

Start-up and push back approval are issued taking into account the TOBT and TSAT. The sequence of the start-up and push back request is no longer a factor. The following rules apply:

4.4.2  Start-Up and Push Back Procedures  Pilot shall ensure that aircraft is ready for start-up and

  1. Push back, or

  2. In case of self-manoeuvring authorized by Airport Authority, the aircraft shall be ready to power back then taxi or taxi out from parking stand.


  1. For IFR flight, pilot shall contact CDC (127.7MHz) for ATC Clearance within 5 minutes prior to TOBT (Period: TOBT - 5 minutes) and monitor defined ground frequency without delay.

  2. ATC may verify or advise any changes of TSAT due to air traffic clearance restriction or flow measures.  Pilot shall monitor defined ground control frequency in accordance with aircraft parking stand. If there is any change of TSAT, Ground Control will update the pilot as soon as possible.  Pilot shall contact Ground Control for start-up and push back within window (TSAT +/- 5 minutes). In case of self-manoeuvring operation after start-up completed pilot shall also request power back then taxi or taxi out in a period of TSAT window. When the pilot request for pushing back, these three scenarios may occur:

  1. Before TSAT window: Flight will be requested to call again when it is within the TSAT window.

  2. Within TSAT window: Flight will be planned for outbound sequence and may expect start-up approval directly or within a few minutes depending on actual operational situation.

  3. After TSAT window: The TSAT of the flight has expired. Flight will be denied start-up approval. Pilot has to contact its AO/GH to update the TOBT and shall contact ATC again when TOBT update has resulted in an updated TSAT.  Ground Control will issue start-up and push back clearance taking TSAT into account.


The aircraft may be allowed to commence pushback before the assigned time (TSAT) due to traffic condition such as bay replacement, and etc. However, the flight should not expect an earlier departure time as the planed pre-departure sequence will be maintained  If a flight is unable to push back due to the aircraft being unready, TSAT will be cancelled. Pilot must notify the AO/GH to update the TOBT for a new TSAT.

  1. Non-compliance to initial TSAT may result in an aircraft losing its existing position in the pre-departure sequence. Delays can be expected as a result of re-sequencing based on new TOBT input.

  2. Flight will not be allowed to depart until a valid TOBT is entered and revised TSAT is given and complied with.


5.1  Adverse Conditions consist of collaborative management of the capacity of an airport during periods of predicted or unpredicted reduction of airport capacity. The aim is to achieve a common situation awareness for the A-CDM partners, including better information for the passengers, in anticipation of a disruption and expeditious recovery after the disruption.

5.2   In case of adverse conditions or any circumstances where predicted or unpredicted reduction of airport capacity may be expected, the following procedures shall be applied:

5.2.1  The pilot shall contact Ground Control for start-up and push back at TSAT +/- 5 minutes.

5.2.2  If there is any change of TSAT, Ground control will update the pilot accordingly.


6.1  In case of unavailability or maintenance of iDEP system, TSAT will not be provided and Non A-CDM Operation shall be performed.

6.2  During period of Non A-CDM Operation, pilot shall request for ATC clearance when the aircraft is ready for pushback. ATC will then issue start-up/pushback clearance on a first-come-first-serve basis.


7.1  A-CDM Contact Desk

  1. Tel: +662 515 3288, +662 535 4011

  2. Email:

7.2  Detailed information on A-CDM procedures and application, please contact A-CDM Team at


8  This AIRAC AIP Supplement supersedes AIP Supplement A24/22 and will remain current until 31 October 2024. Any changes to this AIRAC AIP Supplement will notified through NOTAM.