Avoid Newark Liberty International Airport, if you can: 40 of the 100 most-delayed flights in the nation fly into or out of the New Jersey airport, according to The Wall Street Journal. The worst are two Delta flights to Atlanta, departing daily at 5 p.m. and 6:25 p.m. One reason for the delays is that many Newark flights pass through Washington, D.C., airspace, which is heavily congested.