Learn how SIDs and STARs work with simulator ATC, load the cleared route, handle runway changes and fix ATC/FMS disagreements.
In real-world aviation and flight simulators, ATC may include a SID and STAR in the IFR clearance, then confirm or amend them as runways and traffic change. Load the cleared procedure and transition in the FMS or GPS, verify every waypoint, and obey later ATC instructions when they override the published route.
What does ATC actually clear?
A SID connects the departure runway to the en-route structure, while a STAR brings the aircraft from the en-route structure towards the destination terminal area. Each may contain runway branches, transitions, waypoints, altitude constraints and speed restrictions.
The filed flight plan is a request, not authority to fly every procedure exactly as entered. ATC may clear the filed SID, replace it, issue radar vectors or send the aircraft directly to a later fix. A STAR may be present in the original route, but the runway transition and approach are often confirmed nearer the destination.
Wording and its precise effect vary by country and simulator. These are the common meanings:
| ATC instruction | What it normally means | Pilot action |
|---|---|---|
Cleared via [SID] | Fly the named departure route and transition. | Load its lateral path, then follow the separately cleared altitude and any applicable restrictions. |
Climb via [SID] | Where this phraseology is used, comply with the procedure's published vertical restrictions up to the cleared limit. | Verify every constraint before relying on VNAV. |
Proceed direct [fix] | Intermediate legs are no longer part of the clearance. | Use Direct-To or rebuild the active leg, checking that the aircraft will turn the intended way. |
Expect vectors | ATC will provide headings rather than an uninterrupted published path. | Use heading mode and do not force LNAV across a deliberate vector gap. |
Descend via [STAR] | Where used, fly the arrival and comply with its applicable altitude and speed restrictions. | Check the cleared lower limit and monitor VNAV rather than assuming it will meet every restriction. |
An explicit heading, altitude, speed or direct-to instruction takes precedence over the route previously cleared. Simulator ATC sometimes simplifies real phraseology, so follow the latest displayed or spoken instruction when the aim is to remain compliant with that ATC system.
How do you load the same SID or STAR as ATC?
The ATC flight plan and the cockpit navigation plan must describe the same route. A mistake we see constantly is filing one procedure in the simulator's planner and entering another in the aircraft's FMS.
- File the route used by ATC. Built-in ATC normally works from the simulator's filed plan and may not recognise later edits made only inside an add-on aircraft. Microsoft Flight Simulator users can follow our guide to filing a route and using built-in ATC.
- Copy the complete procedure identity. Check the runway, SID or STAR, en-route transition and runway transition. Matching the procedure name but selecting the wrong transition can create a loop or place the aircraft on the opposite side of the airport.
- Enter it in the aircraft. Select the procedure through the FMS, MCDU or GPS rather than typing every fix manually where possible. Our worked Airbus A320 MCDU route setup shows how the runway, procedure, transition and approach fit together.
- Inspect the legs page. Confirm the first fix, transition, en-route join, altitude constraints and direction of every turn. Resolve unintended discontinuities and duplicate fixes, but retain a vector discontinuity when ATC is expected to issue headings.
- Fly the latest clearance. If ATC changes the runway, procedure or transition, amend the route and review it again before activating LNAV or VNAV.
If procedures are absent from X-Plane's avionics, check how X-Plane 12 loads SIDs and STARs from its navigation data. A missing procedure is often a database or aircraft-avionics issue rather than an ATC fault.
Why do ATC and the FMS disagree?
ATC/FMS disagreements usually come from separate flight plans, mismatched navigation data or a runway change that updated only part of the route.
- Separate plans: built-in ATC is following the route filed in the simulator, while the aircraft is following edits made only in its FMS. Amend or refile the ATC plan where the simulator permits it.
- Different navigation data: the simulator, ATC engine and add-on aircraft may not share the same procedure revision. If a name or transition is missing, use a route both systems recognise rather than forcing a superficially similar procedure.
- Wrong transition: the same SID or STAR can have several entry or exit points. Compare the cleared transition with the legs page, not merely the procedure name.
- Runway reassignment: changing only the approach can leave the old STAR runway branch in place. Reload the arrival and approach together, then remove any duplicated legs.
- Intentional vectors: a discontinuity before final approach may represent radar vectors. Deleting it and connecting the legs can make the aircraft turn towards final before ATC has cleared it.
- Built-in ATC limitations: scripted ATC may issue late descents, unsuitable runways or instructions that do not account for an aircraft's performance. Request an alternative where possible; otherwise prioritise a stable approach and go around if necessary.
Choose the built-in ATC route when you want its instructions and flight-plan tracking to remain consistent. When dynamic vectoring, amendments and realistic controller interaction matter more, compare the available options for more realistic simulator ATC.
Does ATC fly the SID or STAR for you?
No. ATC assigns or approves the route; the pilot flies it manually or uses the aircraft's automation.
LNAV normally follows the lateral legs, while VNAV may calculate climbs and descents through published constraints. Not every simulated aircraft has functional VNAV, and even sophisticated systems can miss a restriction after a route edit. Monitor the modes, altitude selector and vertical path rather than treating an armed mode as proof that the clearance will be met.
When ATC gives vectors, select the assigned heading instead of leaving LNAV to follow the published route. After ATC clears the aircraft direct to a fix or back onto the procedure, confirm the active leg before re-engaging LNAV.
Is a STAR the same as an approach?
No. A STAR ends in the terminal area, while an instrument approach provides the path towards a runway or missed-approach point. The two can connect, but ATC may vector the aircraft off the STAR and intercept the approach at a different fix.
Being cleared for a STAR does not by itself mean the aircraft is cleared for the approach or to land. Keep the approach loaded and checked, but wait for the applicable ATC clearance before treating it as active.
What should you do after an ATC runway change?
A runway change can alter the SID or STAR branch, transition, approach and expected track, so changing the runway field alone is not enough.
- Confirm the new clearance, including the runway, procedure, transition and approach.
- Reload the affected procedure in the FMS or GPS rather than editing isolated waypoints unless the avionics requires manual changes.
- Review the complete route for loops, duplicate fixes, discontinuities and obsolete altitude constraints.
- Check the active leg and modes before selecting Direct-To, LNAV, VNAV or approach mode.
- Reassess the descent. If the change leaves insufficient distance for a stable approach, request delay vectors, enter a hold if cleared, or go around.
For actual flying, the live ATC clearance, current authorised charts and applicable regional procedures take precedence. Simulator ATC is useful practice, but its route logic and phraseology may not reproduce every real controller instruction correctly.