COW=Cell on Wheels. A flying COW is a drone-supported cell site.
Here is another example of how drones are being used in disaster response "today" to improve our collective ability to respond and recover from disasters. See this piece that explains what AT&T did in Florida, AT&T Uses “Flying Cow” Drone to Restore Service to Areas Impacted by Hurricane Michael.
The tethered drone is a great way to provide a broader reach of cell service in a wide variety weather conditions.
Note, I did not see them mention FirstNet in this article.
And, if you are into drones, you might want to sign up and get plugged into UAV Coach.
Jaime Quick provided the link above.