Route reliability record
MKE→BOS
Milwaukee to Boston
- Flights
- 736
- Period
- September 2025 to August 2026
- Distance
- 860 mi
- Carriers
- 3
This route carries a cancellation problem, not just a delay problem: 3.4% of scheduled flights never operate, against 1.9% 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 736 MKE to BOS flights, with a median arrival 9 minutes early.
Best time to fly MKE to BOS: a 8am–11am departure, ideally on a Thursday. Flights in that window arrived on time 86.8% of the time and Thursday flights 74.8%, against 72.1% for the route overall.
The national on-time rate over the same period is 77.3%, so this route runs 5 points behind the country as a whole. Across a thousand flights that is about 52 extra late arrivals.
Key figures
On time
72.1%
Arrivals under 15 minutes late, of 710 completed flights
Avg delay
62 min
Across delayed arrivals only, not all flights
Cancelled
3.40%
National rate is 1.89%
Best carrier
Republic
72.7% on time across 540 flights
These figures cover 736 flights between September 2025 and August 2026. Beyond the headline rate, 10.7% 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 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 | 540 | 72.7% | 65 min | 4.07% | C− |
| JetBlue Airwaysthin sample | 172 | 71.8% | 55 min | 1.16% | C |
| Delta Air Linesthin sample | 24 | 60.9% | 58 min | 4.17% | D− |
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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 36 points, against half a point between the best and worst carrier.
- 5am–8am75 flights75.4%
- 8am–11am108 flights86.8%
- 11am–2pm226 flights68.2%
- 2pm–5pm84 flights51.2%
- 5pm–8pm172 flights77.0%
- 8pm–5am71 flights72.9%
Scale runs 45% to 90%.
Book the morning departure. Flights leaving between 8am–11am arrive on time 86.8% of the time, against 51.2% for the afternoon window. That is 36 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 226 flights scheduled in it.
Explore
Filter MKE to BOS 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 MKE to BOS, the best departure window is 8am–11am at 86.8% on time and the worst is 2pm–5pm at 51.2%, a wide gap of 35.6 points. All US flights leaving 8am–11am ran 83.9%.
- 5–8am75.4%
- 8–11am86.8%
- 11am–2pm68.2%
- 2–5pm51.2%
- 5–8pm77.0%
- 8pm–5am72.9%
best all US flightsScale 45% to 95%.
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. July was the busiest month here, with 84 flights.
Across the week, Thursday is the strongest day at 74.8% on time and Monday the weakest at 67.3%, a spread of 8 points.
Delay causes
Why this route gets delayed
National Airspace System accounts for 43% of the 12,000 delay minutes carriers reported here, and the remaining four split what is left.
- 43%National Airspace System
- 26%Late-arriving aircraft
- 20%Carrier
- 11%Extreme weather
Extreme weather accounts for 11% 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 1.9 times the usual weather exposure. The split is drawn from 12,279 reported delay minutes.
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 5,265 minutes out of 12,000, against a national NAS share of 21%.
Cancellations run at 3.40%, against 1.89% 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
10.7% 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 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.
The return leg is a different operation and performs like one: it runs 82.7% on time across 737 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. 736 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 3.40% 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. 710 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 four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 27.9% of the 736 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
How reliable is MKE to BOS compared with the rest of the country?
72.1% of flights arrive on time here against a national 77.3%, a difference of 5 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 86.8% on time. The 2pm–5pm window is the weakest at 51.2%, 36 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
- Milwaukee Mitchell International (MKE) delay statistics
- Boston Logan International (BOS) delay statistics
- Republic Airways on MKE to BOS72.7%
- JetBlue Airways on MKE to BOS71.8%
- MKE to ORD, a related route68.4%
- DCA to BOS, a related route70.1%
- MKE to DEN, a related route78.8%
- Republic Airways on-time record72.7%
- JetBlue Airways on-time record71.8%
- Delta Air Lines on-time record60.9%
- The US routes with the most cancellations
- The best time of day to fly, according to 7.05 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.