Crazy that an airline that is very used to the need for double- and triple-redundancy in the aircraft it flies fails to have any sort of connectivity backup for it's ground systems.
They have the legal obligation to have those double/triple redundant systems in their aircraft. Otherwise it is probable they would not have as many safety systems.
Does anyone know if these systems are such high bandwidth that they couldn't run with 4G or 5G temporarily? Perhaps some flights, say 25%, could actually still be processed?
Attaching a 4G modem to the end of an existing enterprise network is a non-trivial feat.
Right. I'm not even sure the interconnect is IP-based. It could very well be a legacy X.25 network. A quick check of Wikipedia says that X.25 is still used in the aviation industry. Routing X.25 over 4G probably involves adding a layer to encapsulate in IP.
This is Germany. I bet they have at least one company nobody heard of that makes money hand over fist specifically by doing X.25 over IP for industrial plants.