Your best shot for work and conversion of MultiGen formats (.flt) is to use the open source Blender software. With this program you should be able not only to edit, but also export .flt files to or from several other 3D formats or 2D CAD format, including common DXF format. But of course, there may be more programs capable of this conversion.
Convert AutoCAD DXF Drawing Exchange Format to MultiGen Open FLighT file.
We found one software available in the database for this conversion.
Microsoft Windows software - convert dxf to flt on Windows
A very popular free program used for work with 3D graphics
Convert from dxf file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.