Route reliability record
ATL→ORD
Atlanta to Chicago
- Flights
- 6,493
- Period
- September 2025 to August 2026
- Distance
- 606 mi
- Carriers
- 9
This route sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 8 points worse than the national rate of 77.3%. The late ones land an hour and a half behind schedule. That rests on 6,493 ATL to ORD flights, of which United Airlines flew 1,717 at 72.7% on time.
Best time to fly ATL to ORD: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 85.9% of the time and Saturday flights 72.7%, against 69.0% for the route overall.
United Airlines is the most reliable of the four carriers covered here at 72.7% on time across 1,717 flights.
Key figures
On time
69.0%
Arrivals under 15 minutes late, of 6,303 completed flights
Avg delay
83 min
Across delayed arrivals only, not all flights
Cancelled
2.40%
National rate is 1.89%
Best carrier
United
72.7% on time across 1,717 flights
These figures cover 6,493 flights between September 2025 and August 2026. Beyond the headline rate, 12.0% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Which airline is most reliable on ATL to ORD
The choice of carrier is not cosmetic here. United Airlines arrives on time 72.7% of the time; Frontier Airlines manages 64.4%. Sample sizes sit next to every figure, because a two-point gap across 716 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| PSA Airlinesthin sample | 1 | 100.0% | — | 0.00% | A+ |
| SkyWest Airlinesthin sample | 40 | 84.2% | 88 min | 5.00% | B− |
| Spirit Airlinesthin sample | 16 | 81.2% | 24 min | 0.00% | B+ |
| United Airlines | 1,717 | 72.7% | 92 min | 1.81% | C |
| Envoy Airthin sample | 363 | 71.3% | 83 min | 2.20% | C |
| American Airlines | 754 | 68.3% | 115 min | 2.52% | C |
| Delta Air Lines | 2,631 | 67.6% | 63 min | 2.20% | C |
| Republic Airwaysthin sample | 255 | 66.2% | 79 min | 6.27% | C− |
| Frontier Airlines | 716 | 64.4% | 107 min | 3.07% | D− |
Frontier Airlines cancels 3.1% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.
Flight by flight
Flights on ATL to ORD
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
- Delta 273815:5057.6% · 365 flights
- United 51615:4070.8% · 362 flights
- Delta 147713:0272.9% · 356 flights
- Delta 114709:0079.0% · 351 flights
- Delta 287917:4245.6% · 344 flights
- Frontier 144106:3572.7% · 342 flights
- Delta 119922:5070.6% · 328 flights
- Delta 117807:3087.4% · 325 flights
- United 104618:5960.9% · 320 flights
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Best ways to make this trip
The most reliable ways to fly Atlanta to Chicago
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 2 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. ATL → MDWAtlanta to Chicago | Delta Air Lines | 80.0% | 81.9% | 2.35% | 11am–2pm, Tue | DL 2417 11:00 |
| 2. ATL → MDWAtlanta to Chicago | Southwest Airlines | 72.6% | 73.7% | 1.56% | 5am–8am, Wed | — |
| 3. ATL → ORDAtlanta to Chicago | United Airlines | 71.4% | 72.7% | 1.81% | 8am–11am, Sat | UA 516 15:40 |
| 4. ATL → ORDAtlanta to Chicago | American Airlines | 66.6% | 68.3% | 2.52% | 5am–8am, Fri | — |
| 5. ATL → ORDAtlanta to Chicago | Delta Air Lines | 66.1% | 67.6% | 2.20% | 5am–8am, Sat | DL 1178 07:30 |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 34 points, against 8 points between the best and worst carrier.
- 5am–8am798 flights85.9%
- 8am–11am1,087 flights78.8%
- 11am–2pm1,231 flights77.6%
- 2pm–5pm1,084 flights64.5%
- 5pm–8pm1,264 flights52.3%
- 8pm–5am1,029 flights60.0%
Scale runs 45% to 90%.
The 5pm–8pm window is where this operation falls apart: 52.3% on time, against 85.9% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 5pm–8pm window is the busiest, with 1,264 flights scheduled in it.
Explore
Filter ATL to ORD by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On ATL to ORD, the best departure window is 5am–8am at 85.9% on time and the worst is 5pm–8pm at 52.3%, a wide gap of 33.6 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am85.9%
- 8–11am78.8%
- 11am–2pm77.6%
- 2–5pm64.5%
- 5–8pm52.3%
- 8pm–5am60.0%
best all US flightsScale 45% to 95%.
Across the year
When delays peak on this route
This route's year swings by 26 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
September is the best month on the calendar at 84.4% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. August was the busiest month here, with 626 flights.
Across the week, Saturday is the strongest day at 72.7% on time and Sunday the weakest at 64.1%, a spread of 9 points.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 162,000 reported delay minutes.
- 39%National Airspace System
- 30%Late-arriving aircraft
- 25%Carrier
- 6%Extreme weather
- 0%Security
39% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 63,000 minutes out of 162,000, against a national NAS share of 21%. The split is drawn from 162,445 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 85.9% on time here.
Cancellations sit at 2.40% against a national 1.89%, which is ordinary. Diversions add another 0.52%.
Connections and stage length
What a delay here actually costs
12.0% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
The 606 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.
The return leg is a different operation and performs like one: it runs 74.1% on time across 6,495 flights, 5 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 5 points of difference.
The sample behind these figures is 6,493 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
Work out the risk of missing a connection in ORD after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 84.4% on time and March 58.5%, a swing of 26 points. If the dates move at all, move them out of March before you think about anything else. 6,303 completed flights over 12 months sit behind that.
Common questions
ATL to ORD questions
How often is ATL to ORD delayed?
About one flight in three arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 31.0% of the 6,493 flights in this analysis, against 22.7% nationally. Delayed flights are late by an hour and a half on average.
Which airline is most reliable on ATL to ORD?
United Airlines leads at 72.7% on time across 1,717 flights. Frontier Airlines is at the other end on 64.4%, a gap of 8 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on ATL to ORD?
The 5am–8am departure window is the strongest at 85.9% on time. The 5pm–8pm window is the weakest at 52.3%, 34 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are March delays on ATL to ORD?
March is the weakest month at 58.5% on time, compared with 84.4% in September. Across the year that is 26 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- ORD to ATL — the return legseparate record
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Chicago O'Hare International (ORD) delay statistics
- United Airlines on ATL to ORD72.7%
- Envoy Air on ATL to ORD71.3%
- American Airlines on ATL to ORD68.3%
- Delta Air Lines on ATL to ORD67.6%
- Republic Airways on ATL to ORD66.2%
- Frontier Airlines on ATL to ORD64.4%
- ATL to LGA, a related route72.3%
- LGA to ORD, a related route66.7%
- ATL to MCO, a related route70.3%
- PSA Airlines on-time record100.0%
- SkyWest Airlines on-time record84.2%
- Spirit Airlines on-time record81.2%
- How often a connection fails at the major US hubs
- The best time of day to fly, according to 7.05 million flight records
Direction matters. ATL to ORD and ORD to ATL are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.