Tag: block time

OM in the News: The Airlines’ On Time Flight Game

Today’s pop quiz: If Delta and American both have flights from Dallas to Detroit leaving at 11 a.m., and both flights take 2 hours, 53 minutes to get to the gate in Detroit, which one is late? The answer: American Flight 43. American schedules that trip at 2 hours, 38 minutes. Delta Flight 653 is scheduled to make the trip in 2 hours, 47 minutes, with 9 minutes of extra cushion. The same travel time could leave American 15 minutes late—tardy in DOT statistics. Delta, only 6 minutes overdue, would be considered on time.

“Every airline gives itself extra cushion in its schedule to account for weather delays, mechanical repairs, air-traffic control slow-ups and a thousand other things that leave planes and passengers stewing,” writes The Wall Street Journal (June 29, 2017). In 2016, 86.5% of Delta domestic flights arrived on time under the DOT’s definition, which is at the gate within 14 minutes of scheduled time. That was best among the 4 biggest U.S. carriers. This on-time performance is a competitive battle. Reliability matters to frequent fliers. Several airlines pay employees bonuses based on on-time arrivals.

This year, Delta’s flights have been scheduled about 9 minutes longer than they actually took, on average, a 6% cushion. In 2009, Delta’s scheduled just 2 minutes of padding, or 1.4%. That year only 78.6% of Delta flights arrived on-time. Better-managing maintenance and employees played a major role.

The airline says it increased scheduled time and decreased ground time for planes. Often airlines bolster ground time, so a 15 minute delay doesn’t impact the next flight. Delta chose the opposite approach: increasing scheduled time– called “block time,” so 80% or more of its flights arrive exactly on schedule, then shortening ground time between flights.

Every minute added to schedules can increase costs: higher crew pay for trips at many carriers, more planes and gates needed to fly the same number of trips. Adding one minute to every flight costs about $10 million in annual expenses.

Classroom discussion questions:

  1. What OM tools can be used to deal with airline scheduling problems?
  2. Why do airlines increase their block time?