Learn how SIDs, STARs and instrument approach procedures connect an IFR flight, what each controls, and how to select and fly them safely.
SIDs, STARs and instrument approach procedures are published IFR procedures for three different phases of flight: a SID takes an aircraft from the departure runway into the en-route structure, a STAR brings it from en route towards the destination, and an instrument approach guides it from the terminal area to a runway or landing decision.
In Aviation & Real-World Flying, these terms describe separate procedures rather than interchangeable names. One IFR flight may use all three, while another may receive radar vectors or direct routing instead.
How do SIDs, STARs and approaches fit together?
They form a logical sequence connecting departure, en-route flight, arrival and the runway, although ATC may insert vectors or shortcuts between them.
Runway → SID → en-route route → STAR → instrument approach → landing or missed approach
| Procedure | Main purpose | Typical connection | Common misconception |
|---|---|---|---|
| SID | Standard Instrument Departure | Departure runway or airport to an en-route fix | It is not merely a route drawn by the FMS; it may contain mandatory climb, altitude and speed requirements. |
| STAR | Standard Terminal Arrival Route, also called a standard instrument arrival in ICAO terminology | En-route structure to the terminal area, approach entry or radar vectors | It does not necessarily take the aircraft onto final approach or authorise descent by itself. |
| IAP | Instrument Approach Procedure | Initial approach fix or feeder route to a landing decision, followed by a missed approach if required | Loading it does not clear the aircraft for the approach or guarantee an automatic landing. |
A SID may be designed around obstacle clearance, traffic flow or both. Its chart can specify runway transitions, en-route transitions, minimum climb gradients, altitude constraints and equipment requirements. Our practical SID and STAR flying guidance covers how to brief and execute those details.
A STAR reverses that job by funnelling arrivals from one or more en-route entry points towards an airport. Some STARs serve several runways and finish at a vectoring point; others connect more directly to an approach transition.
Are SIDs and STARs the same as an instrument approach?
No. A SID is a departure procedure, a STAR is an arrival route, and an instrument approach is the procedure used to reach a runway environment or a point from which a missed approach begins.
An instrument approach normally has initial, intermediate, final and missed-approach segments. Examples include ILS, RNAV or GNSS, VOR and, where still published, NDB procedures. Required equipment and minimum visibility or cloud-base criteria depend on the individual approach and its published minima.
A STAR may terminate at an initial approach fix, but it can also end before the approach and leave ATC to provide vectors. Likewise, an aircraft can join an approach directly without flying a STAR. Not every airport has a SID or STAR, and an IFR clearance may instead use another published departure, direct routing or radar vectors.
How do you choose the correct procedure?
Choose each procedure by runway, route continuity, aircraft capability and published restrictions rather than selecting the first name offered by the FMS.
- Establish the expected runway. Wind, airport configuration, traffic and available approaches influence the runway. A later runway change requires the arrival and approach to be checked again.
- Connect the en-route fixes. The SID should lead towards the planned route, while the STAR entry transition should match the final en-route fix. Our explanation of selecting a STAR by route, runway and transition addresses the decision in detail.
- Check aircraft eligibility. Confirm navigation equipment, performance notes, climb gradients and any aircraft or operational restrictions. A procedure appearing in the database does not prove that the aircraft can legally or physically fly it.
- Verify and brief the chart. Check the procedure name and revision, transitions, restrictions, navigation frequencies where applicable, minima and missed approach. Use our guide to decoding the information on an instrument approach chart if those fields are unfamiliar.
The procedure must also be assigned or cleared by ATC in real-world operations. Filing or loading a SID, STAR or approach is not itself permission to fly it.
Do charted altitude and speed restrictions always apply?
Charted restrictions apply when the procedure and clearance make them operative, but the exact effect of an ATC instruction depends on local regulations and phraseology.
- Lateral clearance: being cleared along a procedure does not universally authorise every published vertical change.
- Altitude and speed constraints: phrases such as “climb via” and “descend via” have defined meanings where they are used. A separately assigned altitude may modify part of the vertical profile.
- Climb gradients: meeting a normal climb profile is not enough when a SID publishes a higher minimum gradient. Aircraft weight, temperature and engine performance matter.
- Approach descent: do not descend merely because the approach is loaded. The aircraft must be cleared and established where the procedure authorises descent.
- Minima: at decision altitude, begin the missed approach if the required visual reference is absent. On an approach using a minimum descent altitude, remain at or above it until landing is permitted or the missed-approach point is reached.
If an instruction is ambiguous or appears to conflict with the chart, real-world pilots query ATC rather than guessing.
Why does the procedure fail in a flight simulator?
Most simulator problems come from an incorrect transition, mismatched navigation data or an automation mode that was never armed.
- Wrong transition: selecting the runway but not the correct en-route transition can create a large dog-leg or send the aircraft back towards an earlier waypoint.
- Chart and database mismatch: waypoint names, restrictions and procedure revisions may differ when the simulator and chart use different data cycles. Match them when practising a specific published procedure.
- Deleted discontinuity: some route gaps represent an intentional vector or manual-termination leg. Do not connect every discontinuity unless the clearance or planned route requires it.
- Inactive guidance: loading a procedure does not automatically select the correct navigation source, activate the intended leg or engage lateral and vertical modes. Understanding how the FMS, GPS and radio-navigation systems provide guidance helps isolate these errors.
- Unbriefed runway change: after changing runway, recheck the transition, frequencies, final approach course, minima and missed-approach routing.
Built-in simulator ATC can sometimes issue vectors or altitudes that do not match the loaded procedure. For structured practice, decide whether the exercise is following ATC instructions or the published procedure; silently combining incompatible instructions teaches the wrong habit.