Learn why a flight simulator runs out of available memory, how to distinguish RAM, VRAM and 32-bit limits, and which fixes work.
Across flight simulators, an “out of available memory” message means the program cannot reserve the memory it needs. The exhausted resource may be system RAM, the operating system’s page file, graphics-card VRAM or, in older 32-bit simulators such as FSX, the program’s address space—not necessarily the unused RAM shown by the system.
What does “available memory” actually mean?
Available memory is a broad label covering several separate resources. The exact error wording and the simulator involved determine which one has been exhausted.
| Resource or limit | Typical signs | Most relevant fix |
|---|---|---|
| System RAM or commit limit | Memory and committed usage approach their limits; other programs may also struggle | Close background programs, restore a system-managed page file and reduce memory-heavy add-ons |
| Graphics-card VRAM | Dedicated GPU memory is full, often with stuttering, missing textures or a crash near detailed scenery | Lower texture resolution, render resolution, terrain detail, clouds and other GPU-heavy settings |
| 32-bit address space | FSX, FS2004 or an older 32-bit Prepar3D release fails near complex airports despite free system RAM | Reduce the simulator’s own memory footprint; installing more RAM does not raise this ceiling |
| Memory leak or faulty add-on | Usage keeps climbing during a repeatable flight or after loading several flights in one session | Update, disable or remove the responsible aircraft, scenery, utility or traffic package |
FSX is a particularly common case. As a 32-bit application, it has a limited virtual address space—roughly 4 GB at most in a typical 64-bit Windows installation, and potentially less in older configurations. Fragmentation can also prevent it from finding a large enough block even before the nominal limit is reached. Our FSX address-space troubleshooting steps cover the simulator-specific fixes and explain why settings such as HIGHMEMFIX do not increase that ceiling.
Modern 64-bit simulators such as Microsoft Flight Simulator 2020 and 2024 are not restricted to FSX’s small address space. They can still exhaust physical RAM, the page-file-backed commit limit or VRAM, however.
Why does it happen near detailed airports or on long flights?
Detailed airports and long sessions accumulate aircraft systems, high-resolution textures, terrain, weather, AI traffic and scenery objects in memory. The destination airport may be the point at which the simulator finally exceeds a limit, even though the flight appeared healthy in cruise.
A mistake we see constantly is stacking a complex aircraft, high-resolution airport, multiple scenery layers and dense traffic, then treating the resulting error as proof that one package is defective. Each item may work alone; their combined memory demand causes the failure.
If usage rises steadily during the same repeatable test and never stabilises, suspect a leaking add-on or simulator defect. If it jumps only when a particular airport or aircraft loads, that content—or the total load around it—is the stronger suspect.
How can I identify which memory has run out?
The quickest diagnosis is to reproduce the problem while watching system RAM, committed memory and dedicated GPU memory separately.
- Record the exact message. An FSX “out of available memory” dialog points towards its 32-bit address limit, while the MSFS 2024 “Memory resources getting low” warning requires checks for RAM, page-file and VRAM pressure. Use our MSFS 2024 memory-warning diagnostic process for that specific message.
- Check memory before the failure. On Windows, Task Manager’s Memory panel shows RAM and the committed total versus its limit. The GPU panel shows dedicated GPU memory. A high percentage alone is not conclusive; look for the resource reaching its limit as the error occurs.
- Test a clean baseline. Load a default aircraft at a default airport with third-party scenery and traffic disabled. If that works, restore add-ons in small groups until the failure returns.
- Repeat the same route. A controlled test distinguishes a consistent content conflict from the cumulative load of several unrelated flights in one session.
If dedicated GPU memory is the resource reaching capacity, follow the targeted MSFS 2024 VRAM reduction advice rather than changing unrelated system-RAM settings.
How do I fix a flight simulator out-of-memory error?
Fix the resource that is actually exhausted instead of applying every performance tweak at once.
- Restart the simulator and computer. This releases retained allocations and establishes a clean test, although it does not cure a reproducible leak or address-space limit.
- Enable a system-managed page file. On Windows, make sure the page file has not been disabled and that its drive has adequate free space. An undersized commit limit can produce a memory error while physical RAM still appears available.
- Reduce the settings that affect the identified resource. For VRAM, start with texture resolution, output or render resolution, terrain detail, clouds and shadows. For RAM or a 32-bit simulator, reduce detailed scenery, autogen, traffic, complex aircraft and high-resolution texture packages.
- Isolate third-party content. Temporarily remove packages from the active add-on location, then return them in batches. Pay particular attention to the aircraft and scenery loaded when the error appears.
- Remove duplicate or conflicting scenery. Two products covering the same airport can load overlapping assets and cause excessive consumption as well as visual conflicts.
- Update the failing component. Install stable simulator, graphics-driver and add-on updates where available. Return CPU, GPU and RAM overclocks to stable settings while diagnosing repeatable crashes.
- Treat 32-bit limits as fixed ceilings. With FSX and other 32-bit simulators, lower the active scenery and traffic load. More physical RAM, a larger page file and memory-cleaner utilities cannot give the application an unlimited address space.
On consoles, page-file and driver adjustments are not available. Restart the simulator, disable suspect add-ons, reduce the available traffic or graphics settings, and test with default content.
Will adding more RAM solve the error?
More RAM helps only when physical memory pressure is the real cause. It will not expand a 32-bit simulator’s address space, add VRAM to the graphics card or repair an add-on that continually leaks memory.
If the simulator closes without a memory warning and none of the monitored resources is near its limit, investigate a broader crash rather than assuming memory is responsible. Our Microsoft Flight Simulator crash checks cover add-on conflicts, corrupted caches, graphics drivers and unstable hardware that can resemble an out-of-memory failure.