The NFL is considering experimenting with a booth umpire, which would operate in essence as a "sky judge," and a senior technology adviser during the preseason, according to Kevin Seifert of ESPN.
Per that report, "each official would have access to video and the ability to either make officiating calls or communicate to the referee based on what they see."
Such positions would give officiating crews a broader perspective on the field and perhaps catch egregious fouls that are sometimes naturally missed by officials only able to focus on a portion of the action at a time.