Alaska Airlines in June once again was the most punctual major U.S. airline with an on-time performance rate of 86.8 percent,

according to FlightStats. On average, North American airlines delivered less than 74 percent of their flights to the gate within 15 minutes of schedule. "Stormy weather significantly impacted June's air traffic performance in North America," according to FlightStats. Among the eight largest U.S. carriers, Delta and US Airways performed above average, delivering 76.4 percent and 74 percent of their flights on time, respectively. Meanwhile, United (73.2 percent), Southwest (72.4 percent), American (70.8 percent) and JetBlue (70 percent) posted below-average on-time performances, according to FlightStats.