If Airlines Got Along Better, There Wouldn’t Be So Many Delays

Schedule in the international airport

MIT study suggests airlines swapping schedules could be a more efficient delay system.

A new study by the Massachusetts Institute of Technology suggests letting airlines distribute delays among themselves could create a more equitable swap schedule, without sacrificing efficiency.

“The price of fairness is small,” says Dimitris Bertsimas, the Boeing Leaders for Global Operations Professor of Management at the MIT Sloan School of Management and co-author of a study published in the journal Transportation Science. Bertsimas co-authored the findings with Shubhum Gupta of MIT’s Operations Research Center.

Delays hit some airlines harder than others due to the Federal Aviation Administration’s (FAA) resolution approach. The FAA currently emphasizes minimizing aggregate system delays nationwide through its air traffic flow-management system’s multiple set of rules. These include ground-delay programs, which hold flights at their departing airports when necessary, and airspace-flow programs, which control arrivals into areas suffering delays, often due to bad weather.

The MIT researchers suggest keeping system-wide delays virtually constant while distributing delays among airlines more evenly. This new approach would allow airlines to swap schedule slots with each other, a result the researchers say is fair without sacrificing efficiency.

Bertsimas and Gupta constructed a model using different rules and allowed airlines to switch certain time slots with each other, with limitations placed on the amount of time any flight could be delayed when such swaps are made.

The researchers then tested their model using data covering six full days of air service randomly selected from 30,000 flights during 2004, 2005 and 2006. The data included the 55 biggest airports in the U.S. and the five biggest airlines at the time — Southwest, American, Delta, United and Northwest.

Bertsimas and Gupta simulated what air traffic would have looked like on those specific days using their alternate system and found that the aggregate delays in the entire air-traffic system were virtually unchanged.

On none of the six days did total delays differ from the empirical results by more than 1 percent, and the mean difference was 0.1 percent. And given the guideline of equalizing delays among airlines, the simulation maintained a scenario in which each airline was able to swap an identical number of flight-schedule slots.

“You can solve a problem the size of the U.S. [air network] in seconds,” says Bertsimas.

[Photo: iStock]