Pre-departure clearance (PDC) is a method of delivering departure clearance via ACARS or private text message. It substitutes the conventional method of obtaining clearance over the frequency of Clearance Delivery (CD) to reduce communication and work required of aerodrome controllers. In the real world, PDC is performed from the data link system of the controller to the dispatch system of the airlines, which then relay the PDC to the flight deck crew via ACARS on the aircraft. This method was first used on VATSIM in 2008. On VATSIM, private text message is readily available which eliminates the need of installing a separate data link tool by the controller and an ACARS tool by the pilot. Hence, PDC is performed via private text messages within Hong Kong FIR.
PDC reduces communication as well as expedite the flow of traffic by allowing clearance delivery the ability to issue more clearances in a given amount of time.
How does it differ from the conventional way of clearance delivery?
Once a pilot has filed a flight plan online, the on-duty clearance delivery (CD) controller will examine the flight plan. If the CD controller determines that the flight plan does not need modifications, a PDC will be issued to the pilot via private text message.
Our PDC is broken into two parts which provide you as the pilot with all of the above information.
This PDC message serves directly as your clearance. Once you received a PDC you will have no need to contact clearance delivery, even for a readback. You will only need to contact clearance delivery if you have a question regarding your clearance. The PDC will also issue the appropriate ground controller frequency through which the pilot can obtain push back and start up clearance. If you do not receive a PDC, simply contact clearance delivery and request your clearance as normal. You will not need to ask for a PDC.
It is best to file your flight plan as soon as possible so the controllers can get you your PDC as soon as possible. The process of issuing should be a fairly quick process, but if busy may take a few minutes. You will not want to file a flight plan and call for clearance 5 seconds later. That will not leave the flight data and clearance delivery controller enough time to process and prepare your flight plan information into a clearance.
These PDCs can greatly reduce radio congestion on the clearance delivery frequency as well as issue clearances with greater efficiency and accuracy. Not to mention add a new level of realism to your simulation.