What's the Best Time to Fly? We Analyzed 7 Million Flights to Find Out

In 2018, 80% of US domestic flights arrived within 15 minutes of their scheduled arrival times — a measure that's considered "on time."

But that doesn't mean every flight has an 80% chance of arriving on time. The Points Guy analyzed more than seven million flights to learn what times of the day are the best -- or worst -- for on-time flights.

The analysis, from US Department of Transportation data synthesized by Diio Mi, was telling. It turns out that one of the most important factors in determining punctuality, no matter where you're flying, is when you're flying.

Sure, there's no question that flying through congested airspace hurts your chances. Even so, a flight through a crowded sky can be perfectly punctual — if it's the first flight of the day for the airplane (what airlines call an "originator" flight). Come evening? That can be a different story, especially if you're on a "terminator" flight -- an airplane's last flight of the day.

To get a more complete picture of the best and worst times to fly, The Points Guy's analysis broke down flights for all of of 2018 on an hour-by-hour basis from 6am through 1am (the hours during which nearly all flights are scheduled to arrive). The verdict? Your chance of an on-time arrival drops dramatically through the day.

It turns out that the 80% day-long average is a composite of wildly different averages at different hours of the day.

The most-punctual times to fly

• 7am to 7:59am (89.8% on time)
• 8am to 8:59am (88.6% on time)
• 9am to 9:59am (87.6% on time)

The least-punctual times to fly

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• 10pm to 10:59pm (72.9% on time)
• 8pm to 8:59pm (73% on time)
• 9pm to 9:59pm (73.3% on time)

The best time of day for on-time flights last year was between 7am and 7:59am, when nearly 90% arrived on time. That's the best hour of the day and the morning is pretty good, in general. Even flights scheduled to arrive between 11am and 11:59am were punctual 85.3% of the time, according to the data.

The last scheduled arrival hour when you can expect to hit that overall 80% average is from 3 pm to 3:59 pm; the on-time rate that hour was 80.6%.

Related: The Best Credit Cards for Airline Lounge Access

After that, punctuality declines noticeably. For the three-hour window from 8pm to 10:59, it falls to about 73% — meaning one out of every four flights during that time was arrived at least 15 minutes behind schedule.

Why does punctuality erode through the day?

First, there are fewer problems in the early morning. The vast majority of planes rest when people do. A typical aircraft has several hours to get back into position for a 6am flight, even if the last flight the night before was terribly tardy. (In the US, a handful of planes serve overnight "red-eye" flights from the West Coast to the East Coast, with little time off before starting their day anew.)

As the day goes on, however, small problems can become big problems as issues cascade through airline systems.

Knowing all of this, why don't airlines simply allow more time for flights later in the day, or — in the jargon of airline schedulers — "pad the block times?" (Block time is the time scheduled for a flight from gate to gate, allowing for taxi time and other factors that can slow a flight, such as airspace congestion.)

Actually, they already do.

United's late-afternoon flights from New York LaGuardia (LGA) to Chicago O'Hare (ORD) are scheduled to take up to 31 minutes longer than the first flight of the morning, according to Diio Mi schedule data. Most differentials usually aren't that dramatic, but airlines do commonly allow an extra 10 to 15 minutes for flights later in the day. Even with the schedule cushion, however, airplanes still don't arrive on time at the rates they achieve earlier in the day.

Further, the eye-popping difference shown in this analysis — a nationwide punctuality rate as high as 90% in the morning versus a rate as low as 73% in the evening — actually understates how much longer it can take you to get where you're going later in the day since even an on-time flight in the evening is often scheduled to take longer in the first place.

Of course, airlines fly all day long for a reason: People need to get places at different times and not everyone would want to fly earlier in the day just to have a better chance of an on-time arrival. But when you do have flexibility, it's worth knowing that a scheduled arrival time in the morning is a pretty good bet. In the evening, it's more of an aspiration.

Scroll down for the full hourly breakdown of our analysis of flights from the full-year 2018.

6am to 6:59 am: 87.9% on time

7am to 7:59 am: 89.8% on time

8am to 8:59am: 88.6% on time

9am to 9:59am: 87.6% on time

10am to 10:59am: 86.2% on time

11am to 11:59am: 85.3% on time

Noon to 12:59pm: 84.7% on time

1pm to 1:59pm: 83.8% on time

2pm to 2:59pm: 82.1% on time

3pm to 3:59pm: 80.6% on time

4pm to 4:59pm: 79.1% on time

5pm to 5:59pm: 76.2% on time

6pm to 6:59pm: 75.4% on time

7pm to 7:59pm: 73.9% on time

8pm to 8:59pm: 73% on time

9pm to 9:59pm: 73.3% on time

10pm to 10:59 pm: 72.9% on time

11pm to 11:59pm: 74.5% on time

Midnight to 12:59am: 73.5% on time