Learn why FSX ATC assigns the wrong altitude, how flight plans and pressure settings cause it, and what to do about unsafe clearances.
In FSX and FSX: Steam Edition, ATC usually assigns an unexpected altitude because it is following the cruise altitude in the active IFR flight plan or issuing a temporary climb or descent clearance. If ATC says you are high or low instead, check the altimeter setting before blaming the clearance.
Is the ATC clearance wrong, or is the altimeter wrong?
The symptom usually reveals whether FSX has issued an unsuitable clearance or your aircraft is reporting a different altitude from the one shown on the instrument panel.
| What happens | Likely cause | What to check |
|---|---|---|
| ATC assigns an unexpected cruise altitude | The active IFR plan contains that altitude, or the wrong plan remains loaded | Check the cruising altitude in Flight Planner |
| ATC repeatedly says you are above or below your assigned altitude | Incorrect pressure setting, a custom gauge mismatch or failure to capture altitude | Compare the local pressure setting, primary altimeter, standby instrument and autopilot mode |
| The clearance seems too low compared with the ground | Confusion between MSL and AGL | FSX clearances use altitude above mean sea level, not height above the terrain |
| The first climb clearance is below the filed cruise level | It is an intermediate restriction | Listen for the expected cruise altitude and subsequent climb clearances |
| ATC ignores the altitude entered in an FMC | Built-in ATC cannot read the add-on FMC | Make the active FSX IFR plan match the FMC route and cruise level |
| A low clearance occurs only near one modified airport | Conflicting airport or terrain elevation data | Test the airport without overlapping scenery |
When operating on local pressure, use the altimeter setting spoken by ATIS or ATC. The default B command can reset a default aircraft’s altimeter to the simulator pressure, but complex add-on aircraft may use custom instruments that must be adjusted separately. At flight levels, set standard pressure when instructed.
If the instrument remains frozen, disagrees with the standby altimeter or changes incorrectly after pressing B, work through our FSX altimeter fault checks before changing the flight plan.
Why does FSX ATC choose an unexpected altitude?
FSX bases its altitude instructions on the active flight plan, legacy navigation data and a simplified sequence of climb, cruise and descent clearances.
- Filed cruising altitude: Built-in ATC normally works towards the altitude stored in the active IFR plan. A saved plan sitting in the flight-plan folder has no effect until it is loaded and used.
- Intermediate climb restrictions: An initial clearance such as 5,000 feet can be temporary even when the filed cruise altitude is much higher. ATC should issue further climb instructions as the flight progresses.
- Traffic separation: ATC may temporarily stop a climb or assign another level because of simulated traffic.
- MSL rather than AGL: At an airport 5,000 feet above sea level, a clearance to 7,000 feet gives only about 2,000 feet of height above the airport.
- Simplified procedures: Default ATC does not understand every published SID, STAR, minimum vectoring altitude or procedure restriction.
- Rigid descent logic: It may descend an aircraft early, keep it high too long or issue several awkward changes near the destination.
- Separate FMC data: Entering a new level in an add-on FMC, GPS or autopilot does not amend the active FSX flight plan.
Does FSX: Steam Edition handle altitude differently?
No. FSX: Steam Edition retains the same basic legacy ATC behaviour, so its altitude logic is not materially more advanced than the boxed edition’s system.
Neither edition gives default ATC a modern, automatically updated set of worldwide procedure restrictions. Newer add-on aircraft and scenery can therefore represent routes or airport layouts that the controller does not fully understand.
How do I correct a wrong FSX ATC altitude?
Correct the active IFR plan before departure, set the altimeter properly and request a revised altitude through ATC rather than silently changing the autopilot selector.
- Confirm which plan is active. Open Flight Planner and verify the route, flight rules and cruising altitude. Our guide to finding, loading and using FSX flight plans explains the difference between a saved file and the plan ATC is actually using.
- Choose a sensible cruise altitude. The value is in feet above mean sea level. Account for terrain, aircraft performance, route direction and any applicable airspace or procedural limits.
- Match the aircraft systems. If an add-on FMC is fitted, enter the same route and cruise level in both the FMC and the active FSX plan. This reduces conflicts but does not make default ATC understand the FMC.
- Listen to the whole clearance. Do not confuse the initial altitude with the final cruise level. Continue following later climb clearances unless doing so would be unsafe.
- Set the correct pressure. Use the setting reported by ATIS or ATC and check both primary and standby instruments. Also confirm that the autopilot has captured altitude rather than remaining in vertical-speed or climb mode.
- Request a different level. Use the higher- or lower-altitude request when it appears in the ATC window. Our guide to opening the ATC menu and selecting available requests covers the relevant controls.
- Monitor terrain yourself. Treat the clearance as an instruction from a limited simulator system, not as a guarantee of terrain or procedure clearance.
A mistake we see often is dialling a new altitude into the autopilot and expecting ATC to recognise it. The selected altitude controls the aircraft; it does not amend the clearance. ATC may continue instructing you back to the assigned level until you request and receive a change.
Can FSX ATC assign an unsafe low altitude?
Yes. FSX can issue a descent or vector that is unsuitable for the surrounding terrain, especially in mountainous areas or where add-on scenery has introduced conflicting airport elevations.
Do not descend into terrain merely to comply with simulated ATC. Stop the descent, maintain a safe altitude and request a higher level. If the controller cannot provide a usable clearance, cancel the simulated IFR service and continue using a safe route and approach.
If the fault occurs at only one airport, suspect scenery rather than the flight plan. Duplicate airport files, incompatible elevation corrections or mismatched mesh can change the apparent runway and ground height; our guide to diagnosing elevated and sunken FSX runways covers the same conflicts that can make an ATC altitude look dangerously low.
Does “Das ist Quatsch” describe the FSX clearance?
“Das ist Quatsch” means “that is nonsense” or “that is rubbish” in German. It can be a fair description of an FSX clearance that would compromise terrain clearance or conflicts with a restriction the legacy controller cannot model.
It is not necessarily nonsense when the assigned altitude is merely an intermediate restriction, is expressed as MSL rather than AGL, or appears wrong because the altimeter pressure is incorrect. Check those three points before rejecting the instruction.
Will FSX ATC follow an FMC, SID or STAR?
No. Default FSX ATC does not read an add-on aircraft’s FMC or reliably honour SID and STAR altitude constraints.
You can include procedure waypoints in an FSX-compatible flight plan, but ATC may still issue its own vectors and altitude changes. Keep the FMC route, cruise level and active FSX IFR plan consistent, then monitor published restrictions and terrain independently.
How do I search Fly Away Simulation for related FSX answers?
Use a focused Google query such as FSX ATC altitude site:flyawaysimulation.com to restrict results to Fly Away Simulation.
Entering only site:flyawaysimulation.com produces a broad listing of our indexed pages. Add the simulator name and exact symptom, such as FSX ATC says above assigned altitude, to find the relevant troubleshooting article.