Route reliability record
ATL→MDW
Atlanta to Chicago
- Flights
- 3,537
- Period
- September 2025 to August 2026
- Distance
- 591 mi
- Carriers
- 3
This route sits in the middle of the pack with a B. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.3%. The late ones land about an hour behind schedule. That rests on 3,537 ATL to MDW flights, of which Delta Air Lines flew 1,359 at 81.9% on time.
Best time to fly ATL to MDW: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 94.2% of the time and Wednesday flights 80.8%, against 75.2% for the route overall.
Delta Air Lines is the most reliable of the three carriers covered here at 81.9% on time across 1,359 flights.
Key figures
On time
75.2%
Arrivals under 15 minutes late, of 3,440 completed flights
Avg delay
67 min
Across delayed arrivals only, not all flights
Cancelled
2.04%
National rate is 1.89%
Best carrier
Delta
81.9% on time across 1,359 flights
These figures cover 3,537 flights between September 2025 and August 2026. Beyond the headline rate, 8.4% 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 MDW
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 81.9% of the time; Frontier Airlines manages 64.8%. Sample sizes sit next to every figure, because a two-point gap across 640 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 1,359 | 81.9% | 56 min | 2.35% | B |
| Southwest Airlines | 1,538 | 73.7% | 62 min | 1.56% | C |
| Frontier Airlines | 640 | 64.8% | 89 min | 2.50% | D |
The spread between Delta and Frontier is 17 points, wide enough that it should decide the booking. On a hundred trips that is 17 more arrivals inside the on-time window.
Flight by flight
Flights on ATL to MDW
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.
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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. 3 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 32 points, against 17 points between the best and worst carrier.
- 5am–8am194 flights94.2%
- 8am–11am787 flights81.2%
- 11am–2pm617 flights84.8%
- 2pm–5pm626 flights76.4%
- 5pm–8pm570 flights62.0%
- 8pm–5am743 flights65.2%
Scale runs 55% to 100%.
The 5pm–8pm window is where this operation falls apart: 62.0% on time, against 94.2% 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 8am–11am window is the busiest, with 787 flights scheduled in it.
Explore
Filter ATL to MDW 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 MDW, the best departure window is 5am–8am at 94.2% on time and the worst is 5pm–8pm at 62.0%, a wide gap of 32.2 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am94.2%
- 8–11am81.2%
- 11am–2pm84.8%
- 2–5pm76.4%
- 5–8pm62.0%
- 8pm–5am65.2%
best all US flightsScale 55% to 100%.
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.
August is the worst month at 64.1% on time, 26 points below September, the best at 90.4%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. July was the busiest month here, with 323 flights.
Across the week, Wednesday is the strongest day at 80.8% on time and Sunday the weakest at 69.1%, a spread of 12 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 47% of the 57,000 delay minutes carriers reported here, and the remaining four split what is left.
- 47%Late-arriving aircraft
- 33%Carrier
- 18%National Airspace System
- 3%Extreme weather
- 0%Security
47% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 57,000 reported delay minutes here, that single category outweighs weather by 18 to one. The split is drawn from 57,032 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 94.2% on time here.
Cancellations sit at 2.04% against a national 1.89%, which is ordinary. Diversions add another 0.71%.
Connections and stage length
What a delay here actually costs
8.4% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
The 591 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 78.7% on time across 3,538 flights, 4 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 4 points of difference.
The sample behind these figures is 3,537 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 MDW 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 90.4% on time and August 64.1%, a swing of 26 points. If the dates move at all, move them out of August before you think about anything else. 3,440 completed flights over 12 months sit behind that.
Common questions
ATL to MDW questions
How often is ATL to MDW delayed?
About one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 24.8% of the 3,537 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on ATL to MDW?
Delta Air Lines leads at 81.9% on time across 1,359 flights. Frontier Airlines is at the other end on 64.8%, a gap of 17 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 MDW?
The 5am–8am departure window is the strongest at 94.2% on time. The 5pm–8pm window is the weakest at 62.0%, 32 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 August delays on ATL to MDW?
August is the weakest month at 64.1% on time, compared with 90.4% 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
- MDW to ATL — the return legseparate record
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Chicago Midway International (MDW) delay statistics
- Delta Air Lines on ATL to MDW81.9%
- Southwest Airlines on ATL to MDW73.7%
- Frontier Airlines on ATL to MDW64.8%
- ATL to LGA, a related route72.3%
- PHX to MDW, a related route70.8%
- ATL to MCO, a related route70.3%
- Delta Air Lines on-time record81.9%
- Southwest Airlines on-time record73.7%
- Frontier Airlines on-time record64.8%
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
Direction matters. ATL to MDW and MDW 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.