Standard Instrument Departures and Standard Terminal Arrival Routes are published procedures that guide aircraft away from and toward busy airports under instrument flight rules. They help pilots and air traffic controllers use the same planned paths, altitude limits, and navigation fixes. This organization reduces radio workload, separates traffic flows, and keeps aircraft clear of terrain and restricted airspace.
SIDs and STARs are especially important when many aircraft are operating in the same terminal area at the same time.
A SID usually begins at a runway and leads an aircraft through a sequence of fixes while it climbs toward the en route airway system. A STAR usually begins from an en route fix and brings an aircraft down toward the approach phase near the destination airport. Both procedures may include altitude constraints, speed limits, headings, turns, and required climb or descent gradients.
Modern aircraft often load these routes into a flight management system, but pilots still verify every clearance against the chart.
Key Facts
- SID = Standard Instrument Departure, a published IFR route from a runway to the en route structure.
- STAR = Standard Terminal Arrival Route, a published IFR route from the en route structure toward an airport approach.
- Climb gradient = altitude gained / horizontal distance, often written as ft per NM.
- Required climb rate = ground speed x climb gradient / 60, with ground speed in knots and gradient in ft per NM.
- Descent rate = ground speed x descent gradient / 60, with ground speed in knots and gradient in ft per NM.
- SIDs and STARs are part of an ATC clearance and must be flown exactly unless ATC gives a different instruction.
Vocabulary
- SID
- A Standard Instrument Departure is a published route that guides an aircraft from takeoff to the en route phase under instrument flight rules.
- STAR
- A Standard Terminal Arrival Route is a published route that guides an aircraft from the en route phase toward an airport approach.
- Fix
- A fix is a defined navigation position identified by a name, coordinates, or radio navigation reference.
- Altitude constraint
- An altitude constraint is a required or limited altitude at a specific point on a procedure.
- Terminal area
- A terminal area is the controlled airspace around an airport where aircraft are departing, arriving, and being sequenced for approaches.
Common Mistakes to Avoid
- Treating a SID or STAR as only a suggestion is wrong because it is part of the IFR clearance when assigned and must be followed unless ATC changes it.
- Ignoring altitude and speed restrictions is wrong because the route path alone does not provide full separation from other traffic or terrain.
- Loading the procedure into the flight computer without checking the chart is wrong because database selections, runway transitions, and en route transitions can be mismatched.
- Confusing a STAR with an approach is wrong because a STAR brings the aircraft toward the approach phase, but a separate instrument approach procedure usually guides the final descent to the runway.
Practice Questions
- 1 An aircraft on a SID has a required climb gradient of 300 ft per NM and a ground speed of 150 knots. What climb rate in ft per minute is required?
- 2 A STAR requires an aircraft to descend from 12,000 ft to 6,000 ft over 20 NM. What average descent gradient in ft per NM is needed?
- 3 Explain why a busy airport benefits from having separate SIDs and STARs instead of letting each aircraft choose its own path between the runway and the en route airways.