Carrier route record
DLATL→ORD
Delta Air Lines · Atlanta to Chicago
- Flights
- 2,625
- Period
- July 2025 to June 2026
- Share of route
- 41%
- Carriers
- 9
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.
Delta on ATL to ORD sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 9 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 2,625 flights. The strongest carrier on the route with a full sample, United Airlines, flew 1,611 at 74.3% on time.
United Airlines is the most reliable of the three carriers covered here at 74.3% on time across 1,611 flights.
Key figures
On time
69.1%
Arrivals under 15 minutes late, of 2,548 completed flights
Avg delay
63 min
Across delayed arrivals only, not all flights
Cancelled
2.21%
National rate is 1.81%
Whole route
70.6%
Every carrier on ATL to ORD, 6,406 flights
These figures cover 2,625 flights between July 2025 and June 2026. Beyond the headline rate, 9.1% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
Delta against every carrier on ATL to ORD
Delta flew 2,625 of the 6,406 flights on ATL to ORD, about 41% of it. Its 69.1% on time is 2 points worse than the route as a whole, which runs 70.6%. Ranked by on-time rate it is number eight of nine carriers on the route, where the range runs from PSA at 100.0% to Frontier at 62.8%. Five of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The choice of carrier is not cosmetic here. United Airlines arrives on time 74.3% of the time; Frontier Airlines manages 62.8%. Sample sizes sit next to every figure, because a two-point gap across 711 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| PSA Airlinesthin sample | 5 | 100.0% | — | 0.00% | A+ |
| SkyWest Airlinesthin sample | 40 | 84.2% | 88 min | 5.00% | B− |
| Spirit Airlinesthin sample | 75 | 83.8% | 38 min | 0.00% | B+ |
| United Airlines | 1,611 | 74.3% | 92 min | 1.55% | C |
| Republic Airwaysthin sample | 287 | 72.4% | 65 min | 5.92% | C− |
| American Airlines | 688 | 72.2% | 98 min | 3.05% | C− |
| Envoy Airthin sample | 364 | 71.3% | 83 min | 2.20% | C |
| Delta Air Lines (this page) | 2,625 | 69.1% | 63 min | 2.21% | C |
| Frontier Airlines | 711 | 62.8% | 111 min | 2.67% | D |
American Airlines cancels 3.0% 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
Delta flight numbers on ATL to ORD
Departure window
When Delta runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 41 points, against 12 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am328 flights87.8%
- 8am–11am365 flights79.5%
- 11am–2pm472 flights79.1%
- 2pm–5pm449 flights63.2%
- 5pm–8pm438 flights46.8%
- 8pm–5am573 flights64.8%
Scale runs 40% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 46.8% on time, against 87.8% 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 8pm–5am window is the busiest, with 573 flights scheduled in it.
Across the year
Delta on ATL to ORD through the year
September is the best month on the calendar at 87.4% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. May was the busiest month here, with 238 flights.
Across the week, Saturday is the strongest day at 72.2% on time and Sunday the weakest at 66.8%. 5 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Delta runs late on this route
One category carries most of the weight here. National Airspace System accounts for 48% of the 49,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 48%National Airspace System
- 35%Carrier
- 10%Late-arriving aircraft
- 7%Extreme weather
- 0%Security
The largest share of delay minutes, 35%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 17,000 of the 49,000 delay minutes reported here. The split is drawn from 49,315 reported delay minutes.
48% 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 24,000 minutes out of 49,000, against a national NAS share of 21%.
Cancellations sit at 2.21% against a national 1.81%, which is ordinary. Diversions add another 0.72%.
Connections and stage length
What a delay here costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.1% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum 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. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The return leg is a different operation and performs like one: it runs 80.4% on time across 2,623 flights, 11 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 11 points of difference.
The sample behind these figures is 2,625 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.
What to do with this
Booking Delta on ATL to ORD
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 87.4% on time and March 51.6%, a swing of 36 points. If the dates move at all, move them out of March before you think about anything else. 2,548 completed flights over 12 months sit behind that.
Related
Where to go next
- ATL to ORD, every carrier
- Delta on ORD to ATL, the return leg
- United Airlines on ATL to ORD74.3%
- Republic Airways on ATL to ORD72.4%
- American Airlines on ATL to ORD72.2%
- Envoy Air on ATL to ORD71.3%
- Frontier Airlines on ATL to ORD62.8%
- Delta Air Lines network-wide record
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Chicago O'Hare International (ORD) delay statistics
- Same route, different airline: where the carrier you pick matters most
- The best time of day to fly, according to 7.04 million flight records
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.