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Evan Horowitz

Do delayed flights really make up time in the air?

On average, delayed flights only make up around 5 minutes of lost time.
On average, delayed flights only make up around 5 minutes of lost time. (Getty Images/File)

When your plane begins to rumble toward takeoff after a long delay, that familiar message from the cockpit can seem so full of promise: “we’ll try to make up some of that lost time in the air.”

But does that ever really happen? Can pilots actually reclaim minutes or hours that had been lost to delay? Sometimes they can, but not often. Delayed flights rarely make up more than a few scant minutes in the air, according to Kristopher Karnauskas, a climate scientist at the Woods Hole Oceanographic Institution.

Karnauskas recently pored over flight information for hundreds of thousands of domestic flights, both eastbound and westbound, morning and evening, on-time and long-delayed, trying to figure out if that oft-heard pilot’s promise could be true. However many ways he crunched the numbers, he found basically the same thing: On average, delayed flights only make up around 5 minutes of lost time.

Why can’t flights make up more time?

The biggest reason is that it’s just too costly. The faster planes go, the more fuel they burn. And maximizing fuel efficiency is an essential part of how airlines stay profitable in an extremely competitive industry.

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Is there no chance of outracing a delay?

Some flights really do make up significant ground. Looking just at flights that were delayed 30-90 minutes, Karnauskas found that about a third of them actually made up a full 15 minutes. In a separate analysis, the data journalism site FiveThirtyEight.com found that planes sometimes speed up when the delay is small enough and there’s a chance of arriving on time.

Before you get your hopes up, though, there are a few things to keep in mind. First, this isn’t unique to delayed flights. A fair number of flights that leave on time also gain 15 or 30 minutes in the air —so you can’t attribute all of this to “making up time.”

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Also, while it’s true that some flights do see big gains, others actually fall further behind. The chart below gives a sense for how balanced this really is. The tallest bar shows the most likely outcome for delayed flights: They make up 5 minutes. And while those flights at the far right of the graph can make up a full hour, those at the far left lose nearly as much.

Source: Kristopher Karnauskas, WHOI.

What should I expect when my flight is delayed?

If you’re not inclined to sit back and appreciate the miracle that is modern airline travel , the best way to deal with a delayed flight may settle in for the long haul. Don’t expect those lost minutes to be erased along the way. A 30 minute delay before takeoff means you’re likely to arrive about 25-30 minutes late, regardless of what you might hear about “making up time in the air.”


Evan Horowitz digs through data to find information that illuminates the policy issues facing Massachusetts and the United States. He can be reached at evan.horowitz@globe.com. Follow him on Twitter @GlobeHorowitz