WineCountry: Correct that atc works far more than just commercial passenger flights. But on a board for frequent airline travelers I don't know that military, private, medical, cargo, etc. flights are relevant. I was looking only at the likelihood of delays that can be relevant to those of us here. This will not fall proportionately across the various sectors, but will hit commercial passenger carriers that use the major airports the hardest. United expects a third of its passengers to be impacted.