Flight Plan Content, ATS Messages and Forms
The message set
Beyond the flight plan itself, you must understand the family of ATS messages and their purposes: the filed plan, the delay message, the departure message, the arrival message, the change message and the cancellation. Each has a defined trigger and a defined recipient. Know which messages are generated automatically by ATS and which you must request or send yourself.
Reading the form
Be able to read a completed flight plan form field by field and to spot an error. Understand the meaning of each item, the permitted codes and the conventions for route and equipment. Know how a change message identifies the field being changed and why the change number matters.
Traps
Questions often test the difference between a plan that is filed and one that is activated, or between an arrival message and a cancellation. Another trap is the delay message: it applies when departure is delayed beyond a threshold, and it is not the same as amending the estimated time. Watch for questions about who is responsible for sending each message when the flight is outside controlled airspace.
Rule of thumb
If in doubt about whether a message is needed, ask what the recipient loses without it. If the answer is search and rescue information, position awareness or coordination with the next unit, send it. Silence is only safe when someone else is known to be sending it on your behalf.