Route reliability record
MKE→ATL
Milwaukee to Atlanta
- Flights
- 2,267
- Period
- July 2025 to June 2026
- Distance
- 669 mi
- Carriers
- 2
This route earns a A. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 12 points better than the national rate of 77.6%. When something does go wrong the average delay runs an hour and a half. That rests on 2,267 flights, with a median arrival 17 minutes early.
Set against the rest of the country, this route's record is 12 points better than the US average of 77.6%. That gap is worth roughly 118 fewer late arrivals for every thousand flights.
Key figures
On time
89.4%
Arrivals under 15 minutes late, of 2,216 completed flights
Avg delay
92 min
Across delayed arrivals only, not all flights
Cancelled
1.90%
National rate is 1.81%
Best carrier
Delta
90.0% on time across 2,205 flights
These figures cover 2,267 flights between July 2025 and June 2026. The median arrival is 17 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
Carrier by carrier
Which airline is most reliable on MKE to ATL
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 |
|---|---|---|---|---|---|
| Delta Air Lines | 2,205 | 90.0% | 96 min | 1.90% | A |
| Frontier Airlinesthin sample | 62 | 67.2% | 55 min | 1.61% | C |
Departure window
The best time of day to leave
Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 2,267 flights.
- 5am–8am730 flights90.0%
- 8am–11am360 flights93.7%
- 11am–2pm374 flights89.3%
- 2pm–5pm404 flights87.6%
- 5pm–8pm399 flights86.1%
- 8pm–5am—
Scale runs 80% to 100%. Rows with fewer than 30 flights show a dash.
The early departures do better, though not dramatically: 93.7% on time for the 8am–11am window against 86.1% for 5pm–8pm. Worth taking if the schedule allows, not worth an extra connection. The 5am–8am window is the busiest, with 730 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 14 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 81.4% on time, against 95.2% 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. May was the busiest month here, with 216 flights.
Across the week, Tuesday is the strongest day at 91.3% on time and Sunday the weakest at 86.0%. 5 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Carrier accounts for 43% of the 22,000 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.
- 43%Carrier
- 27%Late-arriving aircraft
- 17%National Airspace System
- 12%Extreme weather
Extreme weather accounts for 12% 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 2.0 times the usual weather exposure. The split is drawn from 21,747 reported delay minutes.
The largest share of delay minutes, 43%, 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 9,399 of the 22,000 delay minutes reported here.
Cancellations sit at 1.90% against a national 1.81%, which is ordinary. Diversions add another 0.35%.
Connections and stage length
What a delay here actually costs
Badly late arrivals are rare here: only 4.1% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
The 669 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 83.4% on time across 2,267 flights, 6 points below 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 6 points of difference.
The sample behind these figures is 2,267 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 calendar is the biggest lever here, not the carrier or the hour. September runs 95.2% on time and December 81.4%, a swing of 14 points. If the dates move at all, move them out of December before you think about anything else. 2,216 completed flights over 12 months sit behind that.
Common questions
MKE to ATL questions
How often is MKE to ATL delayed?
About one flight in nine arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 10.6% of the 2,267 flights in this analysis, against 22.4% nationally. Delayed flights are late by an hour and a half on average.
How reliable is MKE to ATL compared with the rest of the country?
89.4% of flights arrive on time here against a national 77.6%, a difference of 12 points in its favour. That is worth a A on this site's grading scale.
What time of day has the fewest delays on MKE to ATL?
The 8am–11am departure window is the strongest at 93.7% on time. The 5pm–8pm window is the weakest at 86.1%, 8 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 MKE to ATL?
December is the weakest month at 81.4% on time, compared with 95.2% in September. Across the year that is 14 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
- ATL to MKE — the return legseparate record
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Delta Air Lines on-time record90.0%
- Frontier Airlines on-time record67.2%
- Worst months to fly in the US, ranked by the data
- Late aircraft, weather, or the airline: what actually causes US flight delays
Direction matters. MKE to ATL and ATL to MKE 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, July 2025 to June 2026. Updated monthly. How this data is collected.