It looks like the airlines, motivated by fines of up to $27,500 per passengers for runway delays of over three hours (the new rule took effect April 29th), took the appropriate actions in April to minimize this practice.
Overall on-time performance also improved in April. The 18 airlines that provide information to the Transportation Department flew on-time over 85 percent in April vs. a 79 percent rate the prior year, and 80 percent in March of '10.
U.S. Airways turned in the best on-time performance of major U.S. airlines and ranked third overall behind Hawaiian and Alaska Airlines. The worst on-time performance of major airlines was reported by American Airlines, with its regional airline American Eagle, last among all airlines reporting. The smaller airports flown by some of these airlines, along with bad weather locations in the northern states. A single snowstorm in a northern city can cancel hundreds of flights and delay many more.
Enhancements in the efficient use of New York airspace contributed to more flights taking off and landing on-time. Almost 33 percent of all air traffic in the U.S. flies through the New York area. Delays there often contribute to on-time problems throughout the country. The recent runway construction there has certainly affected the timely arrival of many flights.
One of the big fears of the new runway delay penalties/policy is that the airlines will cancel more flights to avoid being fined. That did not prove to be the case in April which experienced only half of the flight cancelation rate of March of '10 or April of '09.