Mission critical components
NOTAM goes down and US aviation is grounded - so it's clearly a mission-critical application.
One change is that maintenance will now require two employees to be deployed. Good idea, I'm surprised the FAA hadn't already mandated peer-reviewed work for important jobs like this.
Perhaps now would be a good time to ask what, if any, other mission critical systems under their care still allow maintenance to be carried out by an individual working alone - and who signed-off on the risk assessment that allows it!