What are SIDs and STARs in aviation, and how do you fly them?

SIDs (Standard Instrument Departures) guide IFR aircraft from a runway or airport into the en-route structure; STARs (Standard Terminal Arrival Routes) guide them from en-route airspace towards an approach. Pilots fly the cleared lateral path and applicable altitude and speed restrictions, using the chart, navigation data and ATC instructions together.

In our Aviation & Real-World Flying coverage, SID and STAR refer to real-world instrument procedures; the same principles apply when reproducing them in a flight simulator. The line drawn by a flight planner is not the procedure by itself. The published chart, ATC clearance and aircraft navigation system must agree.

SID vs STAR: what is the difference?

A SID organises the departure and initial climb, while a STAR organises the descent and arrival into terminal airspace.

A STAR does not normally take the aircraft all the way to the runway. It may connect directly to an approach, finish at a holding fix or end where radar vectors are expected. The approach is a separate procedure with its own final approach course, minima and missed-approach instructions.

Some SIDs and STARs use conventional VOR or DME navigation. Others require a stated RNAV or RNP capability, and certain legs may demand equipment or performance that not every aircraft can provide.

How do you choose the correct SID or STAR?

Choose the procedure that matches the runway, route connection, transition, aircraft capability and ATC clearance.

• For a SID, match the departure runway and select an exit transition or final fix that leads naturally towards the first en-route segment.
• For a STAR, start with the fix from which the route enters the terminal area, then consider the expected runway, approach and arrival transition.
• Check equipment requirements, minimum climb gradients, altitude limits, speed restrictions and any notes limiting the procedure by aircraft type or operation.
• If ATC assigns a different procedure, runway or transition, the clearance takes priority over the original flight plan.

Without live ATC, a simulator pilot can make a plausible selection from the runway in use and planned route, but it remains a planning choice rather than an ATC clearance. Our method for matching procedures to the runway, route and aircraft covers that decision in more detail.

A common error is selecting the arrival whose line appears closest to the aircraft. That STAR may enter from the wrong direction, contain an unsuitable transition or require a capability the aircraft does not have.

What must you check before flying a SID or STAR?

Before flying the procedure, verify its full identifier, revision, runway, transition, notes, navigation requirements and every applicable restriction.

• Chart and database: Check that the chart and the FMS navigation database represent the same procedure revision. Procedure names, fixes and runway transitions can change between data cycles.
• Clearance: Identify the SID or STAR, transition, assigned altitude and any ATC amendments. A published top altitude does not automatically override an altitude assigned by ATC.
• Lateral route: Compare the FMS legs with the chart fix by fix. Confirm the first leg, turn direction, headings, tracks and any vector or manual-sequencing segments.
• Vertical profile: Mark mandatory altitudes, altitude windows, speed limits and climb-gradient requirements. Confirm that the aircraft can meet them.
• Navigation source: Establish whether the procedure is flown with RNAV guidance, conventional radio aids, headings or a combination of these.

Heading and track are not interchangeable. A heading is where the aircraft’s nose points; a track is its path over the ground. Wind can create a significant difference, so follow the exact term printed on the chart. For the symbols and leg structure, use our guide to tracing fixes and decoding SID and STAR chart restrictions.

How do you fly a SID?

Fly a SID by loading the cleared runway, departure and transition, briefing the opening leg, setting the assigned altitude and monitoring both the aircraft and the published restrictions after take-off.

1. Confirm the clearance. Read back the procedure identifier, transition, runway and assigned altitude. Identify any heading, direct-to or other instruction that replaces part of the published route.
2. Load and verify it. Select the runway, SID and exit transition in the FMS. Compare the resulting legs with the chart rather than accepting the moving-map depiction blindly.
3. Brief the first segment. Know the required initial heading or track, first turn point, first altitude restriction and minimum climb gradient. Do not assume the aircraft should turn towards the next magenta-line fix immediately after lift-off.
4. Configure the guidance. Set the correct navigation source, flight director modes and cleared altitude. Tune and identify any required conventional navigation aids.
5. Fly and monitor. Check the flight-mode annunciator, not just the route display. Confirm that lateral guidance is active and that the climb profile will satisfy each applicable restriction.
6. Apply amendments carefully. If ATC issues a heading, direct-to fix or new altitude, follow it and determine which parts of the original procedure still apply. Ask for clarification if the surviving restrictions are unclear.

A mistake we see repeatedly in simulators is a correctly programmed SID flown in the wrong automation mode. The FMS may contain the route while the autopilot remains in heading mode, or the selected altitude may stop the climb below the expected profile. Our full simulator workflow for flying a SID deals with this departure sequence step by step.

How do you fly a STAR and join the approach?

Fly a STAR by confirming it before top of descent, loading the correct entry and runway transitions, checking the vertical profile and waiting for the appropriate descent clearance.

1. Confirm the arrival plan. Check the STAR, entry transition, expected runway and expected approach against the en-route flight plan and ATC clearance.
2. Load each component. The STAR, runway transition and instrument approach may be separate FMS selections. Review the joins for duplicated fixes, missing legs and intentional discontinuities.
3. Plan the descent. Make sure the aircraft can meet the first altitude and speed constraints without an excessive last-minute descent. An FMS-generated path is guidance, not permission to leave the cleared altitude.
4. Set and monitor the cleared altitude. Procedure-clearance phraseology differs between countries. Terms such as descend via have specific meanings in the United States and should not be assumed to carry the same meaning elsewhere.
5. Manage vectors deliberately. When ATC assigns a heading, use the appropriate heading mode. When cleared direct to a fix, activate the intended leg and check whether the change bypasses any restrictions.
6. Rebrief runway changes. Reload the relevant transition and approach, then compare the changed legs and constraints with the chart before continuing.

A discontinuity between the STAR and approach is not automatically a programming fault. It may represent radar vectors or a manual-sequencing leg. Do not delete it solely to create an unbroken line; first determine how the chart and clearance connect the procedures. Our practical instrument-approach workflow explains what happens after the STAR.

Do you have to obey every altitude and speed restriction?

You must comply with restrictions incorporated into the clearance unless ATC amends or cancels them, but the effect of particular instructions depends on the country and operating rules.

• At requires the fix to be crossed at the stated altitude.
• At or above establishes a minimum crossing altitude.
• At or below establishes a maximum crossing altitude.
• An altitude window requires the aircraft to cross between the published upper and lower limits.
• A speed restriction must be planned separately unless the chart or clearance explicitly ties it to an altitude.

An expect altitude is generally planning information, not authority to climb or descend. Symbols and clearance conventions are not identical across charting systems and jurisdictions, so use the chart legend and applicable rules rather than transferring one country’s phraseology to another.

Can the autopilot fly SIDs and STARs?

A suitably equipped autopilot can track much of a SID or STAR, but it cannot interpret the clearance, confirm procedure eligibility or guarantee compliance without pilot monitoring.

On an RNAV procedure, lateral navigation normally follows the stored legs, while VNAV may calculate or command the vertical profile. Capability varies by aircraft: some systems command climbs and descents, some provide advisory guidance, and others require selected vertical modes. Conventional procedures may need heading, VOR or localiser modes instead.

Always distinguish an armed mode from an active mode on the flight-mode annunciator. Direct-to commands, route discontinuities, manual waypoints and the altitude selector can all prevent the aircraft from following the expected path or honouring later constraints.

Why does the FMS route not match the SID or STAR chart?

Most chart and FMS mismatches result from the wrong transition, different navigation-data revisions or an incorrectly handled connection between the STAR and approach.

Flight simulators can introduce another mismatch: the world map, aircraft avionics and external flight plan may not use the same navigation-data revision. Treat the aircraft’s loaded procedure as something to verify, not as proof that the route is correct.

How should you practise SIDs and STARs in a flight simulator?

Practise one procedure at a time with the chart open, predictable weather and enough margin to pause or repeat a difficult segment.

Start with the lateral path and first few restrictions, then add full vertical planning, runway changes and ATC vectors. Check the active mode after every automation change. The useful skill is not making the magenta line continuous; it is understanding the clearance and recognising promptly when the aircraft is not following it.