Pre-departure Clearance (PDC)

(Last updated: 26 October 2017)

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 follow 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. If the CD controller determines that modifications are needed to your submitted flight plan, the controller will notify you via private message or you may not receive a PDC at all.

This PDC message serves directly as your clearance. Once you received a PDC which comes with a 4-digit identifier, you can simply contact the CD controller with the assigned identifier. 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.

Example 1: (Clearance is issued)

Let’s suppose you are the flight deck crew of CPA401 and you have just submitted the flight plan for your flight from Hong Kong (VHHH) to Taipei Taoyuan (RCTP). The flight plan that you have filed, for example, is as follows:

The CD controller, VHHH_DEL on 121.900, verified that your flight plan is correct and issues the following PDC via private message to you.

If you do not have any questions or concerns, you may contact the CD controller with the identifier 401C, current ATIS and parking number on 121.900.

CPA401:Hong Kong Delivery. Good morning. Cathay 401. Information Alfa. Gate E1. PDC code 401C.

VHHH_DEL: Cathay 401. Good morning. PDC readback correct. Contact Ground South 122.550. Good Day.

After the CD controller verifies the identifier over the radio, the controller will ask you to contact the appropriate ground controller for push back and start-up clearance.