A file with .lan extension is a raster GIS file used by the older versions of ERDAS software application. It is also used by other GIS applications and serves the purpose to store and display satellite and aerial imagery. In addition, it can also store other types of raster data. An ERDAS LAN file may also contain additional information specific to ERDAS such as geo-referencing and layers information.
You can open LAN files with ERDAS IMAGINE and ArcGIS Desktop.
LAN File Format
LAN files are stored to disc in binary file format and is not human-readable. The LAN file format is mostly used in remote sensing and GIS applications. It was, however, replaced by the ERDAS IMAGINE (.IMG) file format.