Route reliability record
ORD→MKE
Chicago to Milwaukee
- Flights
- 5,167
- Period
- June 2025 to May 2026
- Distance
- 67 mi
- Carriers
- 4
This route carries a cancellation problem, not just a delay problem: 4.5% of scheduled flights never operate, against 1.8% nationally. Of the ones that do fly, about two flights in three arrive on time, worth a D− overall. The punctuality figure counts only flights that actually departed, so it flatters an operation that cancels this often. That rests on 5,167 flights, with a median arrival 1 minutes late.
The national on-time rate over the same period is 77.4%, so this route runs 14 points behind the country as a whole. Across a thousand flights that is about 137 extra late arrivals.
Key figures
On time
63.7%
Arrivals under 15 minutes late, of 4,927 completed flights
Avg delay
91 min
Across delayed arrivals only, not all flights
Cancelled
4.53%
National rate is 1.80%
Best carrier
SkyWest
63.3% on time across 4,898 flights
These figures cover 5,167 flights between June 2025 and May 2026. Beyond the headline rate, 17.4% 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
Which airline is most reliable on ORD to MKE
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Republic Airwaysthin sample | 113 | 79.0% | 77 min | 7.08% | B− |
| PSA Airlinesthin sample | 26 | 72.7% | 312 min | 15.38% | C− |
| Envoy Airthin sample | 130 | 63.7% | 67 min | 4.62% | D− |
| SkyWest Airlines | 4,898 | 63.3% | 91 min | 4.41% | D− |
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 20 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am150 flights74.5%
- 8am–11am940 flights72.3%
- 11am–2pm637 flights66.2%
- 2pm–5pm1,043 flights62.3%
- 5pm–8pm1,208 flights55.0%
- 8pm–5am1,189 flights64.4%
Scale runs 45% to 80%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 55.0% on time, against 74.5% 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.
Across the year
When delays peak on this route
This route's year swings by 20 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.
December is the weak month at 53.1% on time, against 73.3% in September. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days.
Across the week, Tuesday is the strongest day at 69.9% on time and Sunday the weakest at 56.7%. 13 points is a smaller lever than departure hour, but it is free.
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 163,000 reported delay minutes.
- 41%Carrier
- 27%Late-arriving aircraft
- 16%National Airspace System
- 16%Extreme weather
Extreme weather accounts for 16% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 2.6 times the usual weather exposure.
The largest share of delay minutes, 41%, 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 66,000 of the 163,000 delay minutes reported here.
Cancellations run at 4.53%, against 1.80% nationally. That is roughly one flight in twenty cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.
Connections and stage length
What a delay here actually costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 17.4% of arrivals land a full hour or more behind schedule, against 8.2% 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.
At 67 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 5am–8am window matters as much as it does.
The return leg runs 66.6% on time across 5,166 flights, within 3 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 5,167 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 this route
Put together: the delay figures matter less here than the 4.53% cancellation rate. A late arrival costs you an hour and a half; a cancelled flight costs you the day. Book the 5am–8am departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic.
Common questions
ORD to MKE questions
How often is ORD to MKE delayed?
Roughly one flight in three arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 36.3% of the 5,167 flights in this analysis, against 22.6% nationally. Delayed flights are late by an hour and a half on average.
How reliable is ORD to MKE compared with the rest of the country?
63.7% of flights arrive on time here against a national 77.4%, a difference of 14 points against it. That is worth a D− on this site's grading scale.
What time of day has the fewest delays on ORD to MKE?
The 5am–8am departure window is the strongest at 74.5% on time. The 5pm–8pm window is the weakest at 55.0%, 20 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 December delays on ORD to MKE?
December is the weakest month at 53.1% on time, compared with 73.3% in September. Across the year that is 20 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
- MKE to ORD — the return legseparate record
- Chicago O'Hare International (ORD) delay statistics
- Republic Airways on-time record79.0%
- PSA Airlines on-time record72.7%
- Envoy Air on-time record63.7%
- What a cancellation rate actually tells you (and what it hides)
- The best time of day to fly, according to 7.05 million flight records
Direction matters. ORD to MKE and MKE to ORD are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, June 2025 to May 2026. Updated monthly. How this data is collected.