¶ Operations at Non-A-CDM Aerodromes
¶ Applicability
The procedures in this chapter apply to all non-A-CDM aerodromes, including AFIS and military aerodromes.
At these aerodromes, departure planning is based on the Estimated Off-Block Time (EOBT) filed in the flight plan. A-CDM target times such as TOBT, TSAT and TTOT are not used.
This chapter is an operational checklist. For the principles behind ATFCM regulations, CTOTs and ready messages, refer to ATFCM Concept.
¶ General Procedures
At non-A-CDM aerodromes:
- The EOBT is used as the reference time for departure planning;
- The controller interface displays the planning time in the E/TOBT column;
- Start-up and pushback are managed according to local procedures; and
- Any applicable CTOT shall be observed.
Where a CTOT has been assigned, start-up and pushback should be planned using the expected taxi time. This reduces unnecessary delay at the runway holding point and assists the aircraft in meeting its CTOT.
CTOT tolerance window
Take-off shall occur between CTOT −5 minutes and CTOT +10 minutes.
¶ Departure List Items
The following table describes each list item:
¶ IFR Clearance and Start-Up
ATC shall issue the IFR clearance in accordance with the applicable local procedures.
¶ Aircraft Without a CTOT
Where no CTOT has been assigned, start-up may be approved together with the IFR clearance.
The flight is not subject to a CTOT-related departure restriction. Start-up, pushback, taxi and departure remain subject to:
- ATC clearance;
- Local procedures;
- Traffic conditions; and
- Flight-plan validity.
¶ Aircraft With a CTOT
Where a CTOT has been assigned, ATC should issue start-up approval at an appropriate time.
The controller shall consider:
- The assigned CTOT;
- The CTOT tolerance window;
- The expected taxi time;
- The runway in use;
- Any anticipated ground delay; and
- The aircraft’s reported readiness.
Start-up should not be approved so early that the aircraft is unnecessarily delayed at the holding point.
¶ EOBT and Off-Block Procedures
At non-A-CDM aerodromes, the EOBT filed in the flight plan is used as the planned off-block time.
The controller interface displays this value in the E/TOBT column. This is an interface convention and does not indicate that A-CDM procedures are active.
If the aircraft cannot operate in accordance with its current EOBT, the flight plan information should be updated as required.
¶ CTOT Procedures
When a CTOT has been assigned, ATC shall manage the departure so that take-off occurs within the applicable tolerance window.
Operational requirement
ATC shall not permit an aircraft to take off outside the tolerance window of CTOT −5/+10 minutes.
The CTOT applies to take-off, not start-up, pushback or arrival at the holding point. These stages shall therefore be planned using the expected taxi time.
If the aircraft cannot depart within the current tolerance window, a revised CTOT shall be obtained before departure.
¶ Ready Message
A Ready (REA) message may be submitted only when an aircraft subject to a CTOT is fully ready for departure. The currently displayed CTOT remains applicable unless it is revised or cancelled.
An REA message may be submitted by:
- Left-clicking the E/TOBT column and selecting READY TOBT; or
- Having the pilot select the ready status through the VDGS website.
The REA message shall only be submitted when the aircraft is fully ready to depart.
Submitting an REA message does not authorise the aircraft to depart outside the currently valid CTOT tolerance window.
For the effect of an REA message on the ATFCM process, refer to ATFCM Concept.
¶ Missed CTOT
If the aircraft can no longer depart within its CTOT tolerance window:
- Do not issue a take-off clearance.
- Right-click the CTOT column.
- Submit the required updated EOBT.
- Wait for a new CTOT to be generated.
- Plan start-up and departure using the new CTOT.
The aircraft shall not take off until a valid CTOT and associated tolerance window are available.