What is the FLT file format?
.flt files are binary 3D scene databases in the OpenFlight format, the dominant standard for real-time visual simulation. The format was originally developed by Software Systems Inc. in 1985 for Evans & Sutherland flight simulation hardware and is currently owned by Presagis. The current specification is OpenFlight 16.5.
OpenFlight organises scene data in a hierarchical record structure. A Header record at the root carries the format version and database metadata; child records form a full scene graph containing Group nodes, Level of Detail (LOD) nodes, Object nodes, face polygons, Degree of Freedom (DOF) nodes for articulated parts, and External Reference nodes linking to sub-databases. Texture files are always stored externally and referenced by path; only one texture map per polygon is supported.
The format includes real-time rendering hints that directly guide image generator (IG) systems in flight trainers and military simulation. Coordinates are stored as double-precision floating-point values for real-world geographic accuracy. .flt files are widely used by defence contractors, flight simulator developers, and urban simulation projects. Presagis Creator is the primary authoring tool; open-source alternatives include OpenSceneGraph and osgEarth.
Security & safety
RISK: LOWBinary 3D scene database; contains geometry, material references, and external texture paths. No executable code. Risk is minimal: carefully crafted .flt files with malicious external reference paths could theoretically point to unintended network locations, but this is theoretical, not a known attack vector.
Format details
in a nutshell- FLIC animation variant (DTA program, Dave K. Mason) - A minor variant of the Autodesk FLIC animation format (.fli/.flc) that uses .flt extension; defined by Dave K. Mason for the DTA (Draw, Transform, Animate) program as a new chunk type to distinguish it from standard FLI/FLC. Extremely rare; the db name 'Autodesk Animator FLIC file' refers to this minor variant, not OpenFlight.
- Filter file (audio/image processing) - Various audio and image processing applications use .flt for filter coefficient files (e.g. IIR/FIR filter definitions); format varies by application.
Programs that open FLT files
Windows4 apps
Presagis Creator
Paid File > Open - the native authoring tool for OpenFlight. Full read/write support all versions.
3ds Max (with OpenFlight plugin)
Paid Import via OpenFlight importer/exporter plugin (historically bundled; check current 3ds Max version for plugin availability).
Okino PolyTrans
Paid Import OpenFlight .flt; export to 3ds, OBJ, FBX, and many other 3D formats. Professional batch conversion pipeline.
FME (Safe Software)
Paid Presagis OpenFlight reader/writer included; use for data integration and format conversion pipelines. 
macOS1 app
OpenSceneGraph / osgViewer
Open-source Build or install OSG for macOS; use osgviewer to open .flt files. 
Linux2 apps
OpenSceneGraph / osgViewer
Open-source Run 'osgviewer scene.flt' to view an OpenFlight scene. OSG includes a production-quality .flt reader/writer (osgDB OpenFlight plugin). Free. Technical details
deep spec| Encoding | Binary, big-endian byte order |
| Record structure | Hierarchical record (chunk) format; each record begins with a 2-byte opcode identifying its type followed by a length field |
| Format version | Stored in the Header record (opcode 1) at bytes 4-5; e.g., 1580 = version 15.8, 1640 = version 16.4; current is 16.5 |
| Scene graph node types | Group, LOD (Level of Detail), Object, Face (polygon), DOF (Degree of Freedom articulation), External Reference, Billboard |
| Texture handling | External only; one texture map per polygon maximum; textures referenced by file path within the database |
| Coordinate precision | Double-precision floating-point (64-bit) for geographic positioning, supporting real-world large-scale terrain databases |
| Compression | None (geometry stored uncompressed; external texture images may use separate compressed formats) |
| LOD support | Native LOD node type with near/far switch-in range parameters to swap mesh complexity based on viewing distance |
| DOF nodes | Degree of Freedom nodes define articulated components (landing gear, control surfaces) with min/max rotation and translation constraints |
| External references | Databases can embed links to sub-databases, enabling modular large-scale scene assembly from reusable tiles |
| Typical file size | 10 KB - 500 MB (single objects to full terrain simulation scene databases) |
| Primary industry | Real-time visual simulation: flight training systems, military image generators (IG), urban simulation, defence contractor deliverables |
| Released | 1985 (Software Systems Inc., for Evans & Sutherland visual simulation systems) |
| Latest version | OpenFlight 16.5 (current as of 2024) |
| Open standard | Yes · royalty-free |
| Specification | www.presagis.com |
FLT conversions
Community Q&A
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