In the 80s and 90s I used to fly checks to all the Federal Reserve cities. The entire system switched to digital captures and transmissions to the banks. Mostly Lear Jets with smaller Cesna 206’s and the like making pickups from bank courier at every little airport all around the country. The Federal Reserve ran an entire airline every night. All gone now.
Sounds like airnet
I use to haul checks from the St Paul mn airfield to us bank Wells Fargo and tcf.
We’d sling bags in to those little planes.
I hear airnet is still around but the checks were probably 95% of their business