NOAA created a completely offline application which is installed on a small Intel NUC hardware and used now in the airplanes after natural disasters (floods, hurricanes, etc) in the USA by pilots as an aid for the planned flying rounds to capture imagery of the affected area properly.
They web app is accessed by the pilots from their iPad via their local WiFi access point.
The offline MapBox GL JS app is used together with [tileserver-php](https://github.com/klokantech/tileserver-php), vector tiles from OSM2VectorTiles and raster tiles from [MapTiler](https://www.maptiler.com/).
The [GeoPortal of Mecklenburg County GIS](http://mcmap.org/geoportal/) is using OSM2VectorTiles in combination
with custom data. The source code is [available on GitHub](https://github.com/tobinbradley/Mecklenburg-County-GeoPortal) and the [accompanying blog post can be read
on Tobin Bradley's homepage](http://fuzzytolerance.info/blog/2016/03/21/GeoPortal-migrated-to-Mapbox-GL-JS/).