Everyone masking for the whole flight. Air conditioning running the whole time there are people onboard. Cleaning between flights and no more than about 70% full (that’s empty middle seats like southwest. ) it’s ok and not much of an issue above what you would experience at the grocery store. However having had to work in this industry all through the pandemic there are people not masking in the airports. People removing masks or refusing to use them onboard. (Although many airlines won’t carry them now) people removing them to “eat or drink” then dragging that out for an eternity. The people who I can only imagine can’t wear underwear correctly that leave their nose hanging out and crews who are unwilling to say something or wear masks properly themselves. Inflight water or snacks should be stopped. Sit down bars should not be allowed at airports. In midway there are concourse central bars that are sitting full with unmasked people all day long. Bringing passengers from all the hotspots together and endangering others. So there are weak spots on the system but over all it’s reasonable as long as precautions are taken. However on top of that people arriving are supposed to self quarantine for 14 days. I’m guessing they walk straight out the front to spread whatever they had around.