Route reliability record
MIA→ORD
Miami to Chicago
- Flights
- 4,464
- Period
- September 2025 to August 2026
- Distance
- 1,197 mi
- Carriers
- 4
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, 6 points worse than the national rate of 77.3%. The late ones land a little over an hour behind schedule. That rests on 4,464 MIA to ORD flights, of which American Airlines flew 3,044 at 72.5% on time.
Best time to fly MIA to ORD: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 86.5% of the time and Tuesday flights 77.0%, against 71.1% for the route overall.
The national on-time rate over the same period is 77.3%, so this route runs 6 points behind the country as a whole. Across a thousand flights that is about 62 extra late arrivals.
Key figures
On time
71.1%
Arrivals under 15 minutes late, of 4,331 completed flights
Avg delay
79 min
Across delayed arrivals only, not all flights
Cancelled
1.93%
National rate is 1.89%
Best carrier
American
72.5% on time across 3,044 flights
These figures cover 4,464 flights between September 2025 and August 2026. Beyond the headline rate, 11.3% 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 MIA to ORD
The two carriers here are closely matched: 3 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Frontier Airlinesthin sample | 46 | 73.3% | 175 min | 2.17% | C |
| American Airlines | 3,044 | 72.5% | 77 min | 1.74% | C |
| United Airlines | 1,087 | 69.7% | 85 min | 1.01% | C |
| Spirit Airlinesthin sample | 287 | 60.8% | 64 min | 7.32% | D− |
No carrier stands out. American tops the table at 72.5%, 3 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Flights on MIA 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.
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Best ways to make this trip
The most reliable ways to fly Miami 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. FLL → ORDFort Lauderdale to Chicago | United Airlines | 74.1% | 74.6% | 0.72% | 5am–8am, Tue | UA 1755 12:26 |
| 2. MIA → ORDMiami to Chicago | American Airlines | 71.2% | 72.5% | 1.74% | 5am–8am, Tue | — |
| 3. FLL → MDWFort Lauderdale to Chicago | Southwest Airlines | 70.7% | 71.7% | 1.34% | 5am–8am, Wed | — |
| 4. MIA → ORDMiami to Chicago | United Airlines | 69.0% | 69.7% | 1.01% | 8am–11am, Wed | UA 1983 12:30 |
| 5. FLL → ORDFort Lauderdale to Chicago | American Airlines | 68.8% | 69.8% | 1.50% | 5am–8am, Tue | — |
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 30 points, against 3 points between the best and worst carrier.
- 5am–8am577 flights86.5%
- 8am–11am735 flights85.9%
- 11am–2pm616 flights78.8%
- 2pm–5pm1,062 flights60.9%
- 5pm–8pm710 flights56.9%
- 8pm–5am764 flights66.3%
Scale runs 50% to 90%.
The 5pm–8pm window is where this operation falls apart: 56.9% on time, against 86.5% 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 2pm–5pm window is the busiest, with 1,062 flights scheduled in it.
Explore
Filter MIA 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 MIA to ORD, the best departure window is 5am–8am at 86.5% on time and the worst is 5pm–8pm at 56.9%, a wide gap of 29.6 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am86.5%
- 8–11am85.9%
- 11am–2pm78.8%
- 2–5pm60.9%
- 5–8pm56.9%
- 8pm–5am66.3%
best all US flightsScale 50% to 95%.
Across the year
When delays peak on this route
This route's year swings by 16 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.
July is the worst month at 61.5% on time, 16 points below November, the best at 77.7%. 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. March was the busiest month here, with 498 flights.
Across the week, Tuesday is the strongest day at 77.0% on time and Sunday the weakest at 62.7%, a spread of 14 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 99,000 reported delay minutes.
- 34%National Airspace System
- 34%Late-arriving aircraft
- 25%Carrier
- 7%Extreme weather
- 0%Security
34% 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 34,000 minutes out of 99,000, against a national NAS share of 21%. The split is drawn from 98,620 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 86.5% on time here.
Cancellations sit at 1.93% against a national 1.89%, which is ordinary. Diversions add another 1.05%.
Connections and stage length
What a delay here actually costs
11.3% 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 1,197 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 runs 73.3% on time across 4,465 flights, within 2 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 4,464 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. November runs 77.7% on time and July 61.5%, a swing of 16 points. If the dates move at all, move them out of July before you think about anything else. 4,331 completed flights over 12 months sit behind that.
Common questions
MIA to ORD questions
How often is MIA to ORD delayed?
Roughly 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 28.9% of the 4,464 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on MIA to ORD?
American Airlines leads at 72.5% on time across 3,044 flights. United Airlines is at the other end on 69.7%, a gap of 3 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 MIA to ORD?
The 5am–8am departure window is the strongest at 86.5% on time. The 5pm–8pm window is the weakest at 56.9%, 30 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 July delays on MIA to ORD?
July is the weakest month at 61.5% on time, compared with 77.7% in November. Across the year that is 16 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 MIA — the return legseparate record
- Miami International (MIA) delay statistics
- Chicago O'Hare International (ORD) delay statistics
- American Airlines on MIA to ORD72.5%
- United Airlines on MIA to ORD69.7%
- Spirit Airlines on MIA to ORD60.8%
- MIA to ATL, a related route74.2%
- LGA to ORD, a related route66.7%
- MIA to LGA, a related route67.4%
- Frontier Airlines on-time record73.3%
- American Airlines on-time record72.5%
- United Airlines on-time record69.7%
- Why the first flight of the morning is statistically safest
- How often a connection fails at the major US hubs
Direction matters. MIA to ORD and ORD to MIA 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.