Fix FSLTL crashes in MSFS 2020 by isolating the injector, models and traffic conflicts, then reducing aircraft load and reinstalling cleanly.
FSLTL usually triggers an MSFS 2020 crash to desktop because its traffic models are damaged or outdated, another traffic add-on is competing with it, or the injector creates more aircraft than the PC can sustain. Update or reinstall FSLTL, remove traffic conflicts, disable built-in AI traffic, and test with lower injection limits.
Why can FSLTL crash Microsoft Flight Simulator?
FSLTL has two main parts: an external injector that creates traffic through SimConnect, and the Base Models package that Microsoft Flight Simulator loads and renders. A fault in either part, or in another add-on interacting with them, can produce a CTD.
- Damaged or outdated files: An incomplete update or an old Base Models installation can fail when MSFS tries to load an aircraft.
- Competing traffic systems: Running built-in AI traffic, another injector, duplicate model libraries or overlapping model-matching rules increases load and can create conflicts.
- Excessive aircraft counts: Busy airports can force MSFS to load many models and textures in a short period, exhausting RAM, VRAM or other simulator resources.
- Problem liveries or model overrides: A third-party livery assigned to an FSLTL model may be the real cause, particularly when the crash consistently occurs as one aircraft spawns.
- Simulator update incompatibility: FSLTL or another Community package may need updating after a major MSFS change.
If the injector window closes but MSFS keeps running, that is an injector failure rather than a simulator CTD. Treat the two faults separately.
How do I confirm FSLTL is causing the CTD?
The reliable test is to compare the same flight with the injector, models and other Community packages removed in stages.
- Choose a controlled flight. Use a default aircraft and stock airport. Close every external traffic injector and temporarily set MSFS Aircraft Traffic Type to Off, Ground Aircraft Density to zero and multiplayer traffic off.
- Test without the FSLTL injector. Leave the Base Models installed but do not start the injector. If the flight remains stable, injection volume or an interaction with the injector is the leading suspect.
- Remove the FSLTL packages. Temporarily move the Base Models and any other FSLTL package out of the active
Communityfolder. Test again without launching the injector. - Test FSLTL alone. Restore only clean FSLTL packages, start with conservative traffic limits and leave every unrelated Community add-on disabled.
- Restore add-ons in batches. If FSLTL works alone, another model library, airport, livery, toolbar tool or injector is conflicting with it.
| Test result | What it indicates |
|---|---|
| Stable until the injector starts | Injector configuration, aircraft volume or an interaction with another external tool |
| Crash stops only after Base Models are removed | Damaged, duplicated or overridden traffic models |
| FSLTL works with every other Community package removed | An add-on conflict rather than FSLTL alone |
| Crash continues with FSLTL completely removed | A wider MSFS, aircraft, scenery, driver or hardware problem |
If the CTD occurs while the flight is loading rather than after traffic appears, use our flight-loading crash isolation checks before blaming the injector.
How do I fix repeated FSLTL crashes?
A clean installation with one traffic system and modest injection limits fixes most repeatable FSLTL crashes.
- Update both FSLTL components. Update the Traffic Injector and Base Models through the same installation manager, then restart Windows. Do not combine a new injector with an old model package.
- Perform a clean reinstall. Uninstall both components, inspect the active
Communityfolder for confirmed FSLTL leftovers, remove duplicate copies and reinstall. Overwriting an old folder can preserve damaged or obsolete files. - Remove competing traffic. Disable other injectors, traffic model libraries and model-matching packages. Set MSFS built-in AI traffic to Off and Ground Aircraft Density to zero while diagnosing the crash.
- Reduce injection demand. Lower the IFR and VFR aircraft limits, reduce the injection radius if that option is available, and set additional parked aircraft to zero. Increase one setting at a time only after a stable test.
- Remove model modifications. Test with the standard FSLTL models and liveries. A crash tied to the same airline, aircraft type or parking position often points to a specific replacement livery or model rule.
- Reduce memory pressure. Lower texture resolution, terrain detail or object detail if crashes occur mainly at large hubs. Leave the Windows page file system-managed and keep adequate free space on its drive.
Our FSLTL installation and traffic-settings walkthrough covers the correct package arrangement and injector sequence. A mistake we see constantly is leaving default AI traffic active alongside FSLTL, which wastes resources and produces duplicate aircraft.
Why does FSLTL crash only at busy airports?
Busy hubs expose resource and model problems because the injector creates many aircraft within a small area and MSFS must load their geometry, textures, sounds and animations quickly.
A random crash after traffic numbers build usually suggests memory or object-load pressure. A crash at the same moment or when the same aircraft appears is more consistent with a damaged model, incompatible livery or model-matching override. Reduce traffic first; if the fault remains precisely repeatable, reinstall the models and remove custom liveries.
What if FSLTL started crashing after an MSFS update?
A crash that begins immediately after a simulator update should be treated as an add-on compatibility problem until a clean test proves otherwise.
Update FSLTL and temporarily remove every unrelated Community package. Do not assume FSLTL is responsible merely because its injector was running; airports, aircraft and toolbar utilities can fail when traffic increases their workload. Follow our post-update add-on isolation procedure if the timing matches a simulator update.
Should I clear the rolling cache or reinstall MSFS?
Neither should be the first response to an FSLTL crash because the rolling cache does not repair traffic models, and reinstalling the whole simulator leaves many external and Community add-ons untouched.
Check the injector console and Windows Reliability Monitor after a CTD, but do not treat the injector's final aircraft entry as proof that aircraft caused the crash. If MSFS still fails with FSLTL and all Community content removed, continue with the broader MSFS crash-isolation sequence for drivers, overlays, caches, memory pressure and unstable hardware settings.