“Boeing E6 Mercury.”
I bet you are correct. In the link it says it flew off towards Oklahoma. That would probably be Tinker AFB. That also fits for it to be a E6.
I’m figuring an E6 that took off from Travis AFB, had some sort of training mission related to silo C&C - hence the time over CO, and landed at Tinker. Travis and Tinker are both E6 homes.