Northwest Airlines was the most punctual major domestic carrier in July

, the third consecutive month it led its peers in on-time performance, according to the latest U.S. Department of Transportation statistics. Continental Airlines for the fourth consecutive month ranked last among the major carriers. U.S. carriers' aggregate on-time performance of 73.7 percent was an improvement over the previous month (72.8 percent) and July of last year (70.9 percent). Year-over-year, total flight cancellations dropped by 2.2 percent.