Route reliability record
ATL→MKE
Atlanta to Milwaukee
- Flights
- 2,264
- Period
- September 2025 to August 2026
- Distance
- 669 mi
- Carriers
- 2
This route lands a B, 6 points better than the national rate of 77.3%. About one flight in six arrives 15 minutes late or worse, and those flights are late by roughly 55 minutes on average. That rests on 2,264 ATL to MKE flights, with a median arrival 6 minutes early.
Best time to fly ATL to MKE: a 11am–2pm departure, ideally on a Wednesday. Flights in that window arrived on time 88.6% of the time and Wednesday flights 88.9%, against 82.8% for the route overall.
Set against the rest of the country, this route's record is 6 points better than the US average of 77.3%. That gap is worth roughly 55 fewer late arrivals for every thousand flights.
Key figures
On time
82.8%
Arrivals under 15 minutes late, of 2,214 completed flights
Avg delay
53 min
Across delayed arrivals only, not all flights
Cancelled
1.90%
National rate is 1.89%
Best carrier
Delta
83.7% on time across 2,202 flights
These figures cover 2,264 flights between September 2025 and August 2026. The median arrival is 6 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.
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Carrier by carrier
Which airline is most reliable on ATL 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 |
|---|---|---|---|---|---|
| Delta Air Lines | 2,202 | 83.7% | 53 min | 1.95% | B |
| Frontier Airlinesthin sample | 62 | 52.5% | 44 min | 0.00% | F+ |
Flight by flight
Flights on ATL to MKE
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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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 16 points, against half a point between the best and worst carrier.
- 5am–8am—
- 8am–11am692 flights87.8%
- 11am–2pm309 flights88.6%
- 2pm–5pm521 flights81.2%
- 5pm–8pm294 flights72.2%
- 8pm–5am448 flights79.7%
Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.
The best window here is not the first bank but the 11am–2pm slot at 88.6% on time, ahead of 5pm–8pm at 72.2%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 8am–11am window is the busiest, with 692 flights scheduled in it.
Explore
Filter ATL to MKE 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 MKE, the best departure window is 11am–2pm at 88.6% on time and the worst is 5pm–8pm at 72.2%, a wide gap of 16.4 points. All US flights leaving 11am–2pm ran 78.3%.
- 5–8am—
- 8–11am87.8%
- 11am–2pm88.6%
- 2–5pm81.2%
- 5–8pm72.2%
- 8pm–5am79.7%
best all US flightsScale 60% to 95%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 22 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 69.6% on time, 22 points below September, the best at 91.4%. 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. May was the busiest month here, with 216 flights.
Across the week, Wednesday is the strongest day at 88.9% on time and Monday the weakest at 77.4%, a spread of 12 points.
Delay causes
Why this route gets delayed
Carrier accounts for 48% of the 20,000 delay minutes carriers reported here, and the remaining four split what is left.
- 48%Carrier
- 27%Late-arriving aircraft
- 20%National Airspace System
- 5%Extreme weather
- 0%Security
The largest share of delay minutes, 48%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 9,646 of the 20,000 delay minutes reported here. The split is drawn from 19,999 reported delay minutes.
Cancellations sit at 1.90% against a national 1.89%, which is ordinary. Diversions add another 0.31%.
Connections and stage length
What a delay here actually costs
Badly late arrivals are rare here: only 4.7% land an hour or more behind schedule, against 8.3% 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.
The return leg is a different operation and performs like one: it runs 88.5% on time across 2,264 flights, 6 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 6 points of difference.
The sample behind these figures is 2,264 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 MKE 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 91.4% on time and July 69.6%, a swing of 22 points. If the dates move at all, move them out of July before you think about anything else. 2,214 completed flights over 12 months sit behind that.
Common questions
ATL to MKE questions
How often is ATL to MKE delayed?
About one flight in six arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 17.2% of the 2,264 flights in this analysis, against 22.7% nationally. Delayed flights are late by roughly 55 minutes on average.
How reliable is ATL to MKE compared with the rest of the country?
82.8% of flights arrive on time here against a national 77.3%, a difference of 6 points in its favour. That is worth a B on this site's grading scale.
What time of day has the fewest delays on ATL to MKE?
The 11am–2pm departure window is the strongest at 88.6% on time. The 5pm–8pm window is the weakest at 72.2%, 16 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 ATL to MKE?
July is the weakest month at 69.6% on time, compared with 91.4% in September. Across the year that is 22 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 ATL — the return legseparate record
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Milwaukee Mitchell International (MKE) delay statistics
- ATL to LGA, a related route72.3%
- ORD to MKE, a related route64.3%
- ATL to MCO, a related route70.3%
- Delta Air Lines on-time record83.7%
- Frontier Airlines on-time record52.5%
- The best time of day to fly, according to 7.05 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. ATL to MKE and MKE 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.