Hi @Matthew_Douglas,
At the present time, for Roon to work properly you need an active Core (at minimum) and a WiFi connection if you have endpoints on the network (such as the iPhone).
You don’t necessarily need internet to play back local content on the Core, but internet is required for metadata updates and periodic license checks.
We are looking into a “on the road” solution and there is an active feature request, but nothing that I can comment on with regard to timeline:
If setting up your laptop is not very convenient on the airplane, I would suggest using the native TIDAL/Qobuz apps with content downloaded and added to your offline playlist until we release a proper on the road solution.
Thanks!