Route reliability record
MKE→BOS
Milwaukee to Boston
- Flights
- 741
- Period
- July 2025 to June 2026
- Distance
- 860 mi
- Carriers
- 3
This route carries a cancellation problem, not just a delay problem: 3.2% of scheduled flights never operate, against 1.8% nationally. Of the ones that do fly, about seven flights in ten arrive on time, worth a C− overall. The punctuality figure counts only flights that actually departed, so it flatters an operation that cancels this often. That rests on 741 MKE to BOS flights, with a median arrival 7 minutes early.
Best time to fly MKE to BOS: a 8am–11am departure, ideally on a Saturday. Flights in that window arrived on time 91.3% of the time and Saturday flights 73.7%, against 69.8% for the route overall.
The national on-time rate over the same period is 77.6%, so this route runs 8 points behind the country as a whole. Across a thousand flights that is about 78 extra late arrivals.
Key figures
On time
69.8%
Arrivals under 15 minutes late, of 716 completed flights
Avg delay
66 min
Across delayed arrivals only, not all flights
Cancelled
3.24%
National rate is 1.81%
Best carrier
Republic
73.1% on time across 549 flights
These figures cover 741 flights between July 2025 and June 2026. Beyond the headline rate, 13.4% 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 MKE to BOS
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 Airways | 549 | 73.1% | 66 min | 4.01% | C− |
| Delta Air Linesthin sample | 20 | 63.2% | 64 min | 5.00% | D− |
| JetBlue Airwaysthin sample | 172 | 60.6% | 67 min | 0.58% | 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 40 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–8am75 flights75.4%
- 8am–11am46 flights91.3%
- 11am–2pm242 flights68.6%
- 2pm–5pm132 flights51.5%
- 5pm–8pm133 flights79.4%
- 8pm–5am113 flights70.6%
Scale runs 45% to 95%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 91.3% of the time, against 51.5% for the afternoon window. That is 40 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 242 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 51 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.
Delays peak in September, when the on-time rate falls to 46.8%. March is the strongest month at 97.8%. Moving a flexible trip across that boundary buys 51 points. August was the busiest month here, with 87 flights.
Across the week, Saturday is the strongest day at 73.7% on time and Wednesday the weakest at 65.7%. 8 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. National Airspace System accounts for 43% of the 14,000 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%National Airspace System
- 27%Late-arriving aircraft
- 24%Carrier
- 6%Extreme weather
43% 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 6,120 minutes out of 14,000, against a national NAS share of 21%. The split is drawn from 14,340 reported delay minutes.
Cancellations run at 3.24%, against 1.81% nationally. That is about one flight in 30 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. 13.4% of arrivals land a full hour or more behind schedule, against 8.1% 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.
The 860 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 80.5% on time across 742 flights, 11 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 11 points of difference.
One caution: this is a thin sample. 741 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
Work out the risk of missing a connection in BOS after this flight
What to do with this
Booking this route
Put together: the delay figures matter less here than the 3.24% cancellation rate. A late arrival costs you about an hour; a cancelled flight costs you the day. Book the 8am–11am departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 716 completed flights over 12 months sit behind that.
Common questions
MKE to BOS questions
How often is MKE to BOS 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 30.2% of the 741 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
How reliable is MKE to BOS compared with the rest of the country?
69.8% of flights arrive on time here against a national 77.6%, a difference of 8 points against it. That is worth a C− on this site's grading scale.
What time of day has the fewest delays on MKE to BOS?
The 8am–11am departure window is the strongest at 91.3% on time. The 2pm–5pm window is the weakest at 51.5%, 40 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 September delays on MKE to BOS?
September is the weakest month at 46.8% on time, compared with 97.8% in March. Across the year that is 51 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
- BOS to MKE — the return legseparate record
- Boston Logan International (BOS) delay statistics
- Republic Airways on MKE to BOS73.1%
- JetBlue Airways on MKE to BOS60.6%
- MKE to ORD, a related route67.4%
- DCA to BOS, a related route71.4%
- MKE to DEN, a related route78.1%
- Republic Airways on-time record73.1%
- Delta Air Lines on-time record63.2%
- JetBlue Airways on-time record60.6%
- The US routes with the most cancellations
- The best time of day to fly, according to 7.04 million flight records
Direction matters. MKE to BOS and BOS to MKE 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.