I’d like to hear the transmissions on the handoff from Denver. Denver controller should have kept trying until he got an acknowledgement. I also wonder how long it took Minneapolis approach to realize the pilots wern’t with them after the handoff.
I flew the area between MSP and SD several times but it has been years ago so I forget where the line is between the centers.
But the flight was at 37,000 if the media reported correctly.
Which means Denver center normally would turn the flight over to Minneapolis Center and and then turned over to MSP approach after getting assigned a lower altitude.
So the guys in approach would do nothing until they got the hand off from center.
Once it was determined the flight was not acting normally, then everyone would alert everyone else and ask each to attempt contract.
But there again, I don’t know where the boundaries are. Too many years have passed.