Departure Instructions

Departure Instructions for Controllers

Controllers may provide detailed departure instructions when required. Expect to receive departure instructions in the following format:

Takeoff Clearance Format

1. (Aircraft Identification) [Unit Identification]
2. (Special Information) – Includes details such as hazards or obstructions.
3. (Control Instructions) – Includes information such as a turn or heading after takeoff.
4. [Wind Information] – If the wind speed is 15 knots or more, the direction and speed are issued in the takeoff clearance.
5. FROM (Intersection/Threshold) – Controllers state the position from which the takeoff roll commences if you are taking off from any of the following:
   • A taxiway intersection
   • A runway intersection
   • The threshold when another entry point for the same runway is also in use
6. CLEARED FOR TAKEOFF (Runway Identification)

Takeoff at Your Discretion

“At your discretion” is used in uncontrolled areas of an airport. This is frequently used for helicopters and seaplanes. Generally, this applies to VFR aircraft, though an IFR aircraft may also receive such an instruction.

Key Considerations:

• You are responsible for safety and separation.
• ATC issues this instruction with the intent that you comply as soon as safely able.
• ATC may be instructing surrounding traffic based on the assumption that you will take off without delay.

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Standard Instrument Departures (SIDs)

To connect airports with the airway system for IFR flights, predefined departure routes, known as Standard Instrument Departures (SIDs), are used. These routes guide aircraft from the departure runway via waypoints and/or conventional navigation aids such as NDBs and VORs to the first waypoint in the flight plan.

With modern airspace complexities, many SIDs no longer rely solely on traditional radio navigation. Instead, most waypoints exist as virtual coordinates, requiring RNAV (Area Navigation) equipment, which is standard in modern airliners.

SID Naming Structure

Each SID follows a standardized naming convention, which consists of:

• Basic Indicator – The last waypoint of the SID or the first waypoint in the flight plan.
• Validity Indicator – A number that is incremented when minor changes are made to the SID (e.g., variations in magnetic deviation).
• Route Indicator – A letter that differentiates SIDs leading to the same waypoint. These differences may be based on factors such as runway assignment, routing variations, altitude restrictions, or other operational constraints.

Example:

📡 MABAP3D departure from Runway 10 in Marrakech

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Route and Clearance Components

When clearing a flight via a SID, controllers must ensure that pilots are aware of the following key instructions:

• Assigned departure runway, which should match the ATIS information.
• Initial climb clearance, specifying the first altitude to be maintained.
• SID routing details, including any altitude or speed restrictions.
• Frequency change instructions after takeoff.

Frequency Change Procedures

In some regions, such as Tunisia, frequency changes after takeoff are explicitly part of the SID procedure at many airports. Pilots should always verify whether they are expected to change frequency autonomously before departure. In such cases, the tower will not provide an explicit handoff, as frequency change instructions will be published in the SID charts and/or ATIS.

Controllers should ensure pilots understand these procedures to facilitate efficient airspace transitions.