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Air operations, On-Time Performance

Chasing the Holy Grail: Why are some airlines seemingly always on time, and others struggle?

November 14, 2022

Trends emerge amongst the airlines that win on-time rankings on a monthly basis.

See the November 2022 On-Time Performance Reports, here.

Regular readers will know that Cirium measures On-Time Performance month in and month out, along with a much-followed annual ranking of on-time performance for airlines and airports globally. Follow those rankings closely, and trends emerge amongst the airlines that win on a monthly basis, those that do not fare so well — and some that don’t actually make the list. Is there rhyme or reason why some airlines win and some do not? 

What, exactly, is on time? 

For a flight to be on time, it must arrive at the gate within 15 minutes — 14:59 in fact — of its scheduled arrival time. (Airport performance is measured by whether flights departed within 15 minutes of the scheduled departure time.) This key performance indicator is referred to as A15. It is not codified by regulatory bodies and there is some variation globally; airlines and airports follow the Cirium definition.  

Jeremy Bowen

The stopwatch starts when the aircraft is off the gate, and ends when rubber chocks are put in place on the ramp at the arrival airport. “Block time is the standard, but not all airlines measure themselves that way,” said Jeremy Bowen, Cirium’s CEO.  “Some start when the door closes, for added time pressure!”  

And, the metric is critical, Bowen said, noting the costs of delay are estimated to be over $80 per minute

The Easy Answer? “Structural” Differences 

“Aviation is an ecosystem,” said Luis Felipe de Oliveira, Director General of Airports Council International, the representative body for the world’s airports.

“If one of the parts of the system fails, you create a domino effect which compounds. If you start the day poorly, you can finish even worse.” 

de Oliveira cited a laundry of list of performance factors, including the relationship between the airline and airport, an airline’s route map and strategy (point-to-point or network carrier), labor availability, fleet composition and of course, the weather.

Luis Felipe de Oliveira

“Each airline has differing and varied challenges,” he said. “Staffing has been a challenge coming out of the pandemic for many airlines and airports but is not so much of an issue in Latin America for example,” de Oliveira said.  

“You can come up with myriad reasons to explain a result. Those structural differences play a role, to be sure, across the 1,300 airlines we measure,” added Cirium’s Bowen. 

But…Delta Air Lines 

Delta Air Lines is instructive. The US-carrier flies a complicated schedule and at congested hubs like LaGuardia, all the while maintaining one of the best on-time performance ratings in the world. Indeed, many smaller carriers with much less complicated route maps and operating conditions had much poorer performance. “Some point-to-point carriers manage operations incredibly well,” said Bowen, noting that cascading delays are more difficult to recover for these carriers. Still others do not seem too bothered by being late — they might hold back a plane to make sure all of their paying customers can get on board. 

Delta tails

“Arrival times look like a normal distribution with a long tail,” said Robert Mann, a long-time airline industry consultant and executive. “In that long tail, there are outcomes that you cannot control for, like weather or air traffic congestion. But, the airlines manage towards a normal distribution and A15 is the target.”  

“It’s just math,” he said. 

How do Airlines Manage to the KPI? 

“If an airline says, ‘What we need to be competitive is to have an 80% on-time performance’, an airline will increase the block time to reflect what will get 80% of the outcomes on the distribution. If, say a 90-minute block time is achievable for a flight — but not frequently — and 95 minutes is within the distribution, they might publish a block time that is 100 minutes and get to 80% of the outcomes,” Mann said. 

Robert Mann

Could an airline then simply expand block time to be 100% on-time? Not practically, Mann said. An airline can achieve 100% on-time performance if they are simply willing to pay for it in capital and operational expense.  

“If you bake in a lot of excess time, you sacrifice aircraft utilization which you can never recover, even if the flight arrives early. You schedule flight crews to match,” Mann said. “And, there will always be some distribution of outcomes for weather or air traffic delays. The utility to the customer goes down when you do that. Yes, you’re on-time but it took forever to get there.” 

What then is the objective? 

“There are elements within your control,” said Mann.

“On departure, there are probably a hundred processes that go into whether the airplane gets out on time. If you get all of those processes right, you’ll create what I call a virtuous cycle. You’re going to reduce the randomness and the padding you’ve included in your schedule, giving you effectively more airplanes and more efficient use of capital.” 

To achieve this virtuous cycle requires management leadership and understanding to see the value in derandomizing outcomes, Mann said.  

“Of course, we’ve never done this. No airline has ever managed as perfectly as I’ve described. It’s the holy grail.” 

Cirium’s Bowen agreed.  

“Top performing airlines recognize that on-time performance benefits more than just the passenger experience.”

“Knowing when your planes are going to take off and with high degree of confidence allows the airline to better manage maintenance, recover faster from weather and related delay events, and reduce delay.”  

Learn more about Cirium On-Time Performance Reports

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