Route reliability record
BOS→MKE
Boston to Milwaukee
- Flights
- 742
- 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 four flights in five arrive on time, worth a B− overall. The punctuality figure counts only flights that actually departed, so it flatters an operation that cancels this often. That rests on 742 BOS to MKE flights, with a median arrival 8 minutes early.
Best time to fly BOS to MKE: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 92.7% of the time and Wednesday flights 85.2%, against 80.5% for the route overall.
The US average over the same twelve months is 77.6%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
80.5%
Arrivals under 15 minutes late, of 717 completed flights
Avg delay
63 min
Across delayed arrivals only, not all flights
Cancelled
3.23%
National rate is 1.81%
Best carrier
Republic
80.8% on time across 549 flights
These figures cover 742 flights between July 2025 and June 2026. The median arrival is 8 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 BOS 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 |
|---|---|---|---|---|---|
| JetBlue Airwaysthin sample | 172 | 83.0% | 68 min | 0.58% | B+ |
| Republic Airways | 549 | 80.8% | 59 min | 4.01% | B− |
| Delta Air Linesthin sample | 21 | 50.0% | 92 min | 4.76% | F− |
Flight by flight
Flights on BOS 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.
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 30 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–8am41 flights92.7%
- 8am–11am244 flights86.6%
- 11am–2pm72 flights81.7%
- 2pm–5pm198 flights80.0%
- 5pm–8pm137 flights62.6%
- 8pm–5am50 flights88.9%
Scale runs 55% to 100%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 62.6% on time, against 92.7% 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. The 8am–11am window is the busiest, with 244 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 27 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 65.6% on time, against 92.4% in June. 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. August was the busiest month here, with 87 flights.
Across the week, Wednesday is the strongest day at 85.2% on time and Friday the weakest at 76.1%. 9 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 8,852 reported delay minutes.
- 41%Late-arriving aircraft
- 38%Carrier
- 21%National Airspace System
- 0%Extreme weather
41% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 8,852 reported delay minutes here, that single category outweighs weather by 41 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 8,852 reported delay minutes.
The largest share of delay minutes, 38%, 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 3,354 of the 8,852 delay minutes reported here.
Cancellations run at 3.23%, 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
7.7% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
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 69.8% on time across 741 flights, 11 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 11 points of difference.
One caution: this is a thin sample. 742 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 MKE after this flight
What to do with this
Booking this route
Put together: the delay figures matter less here than the 3.23% cancellation rate. A late arrival costs you about an hour; 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. 717 completed flights over 12 months sit behind that.
Common questions
BOS to MKE questions
How often is BOS to MKE delayed?
About one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 19.5% of the 742 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
How reliable is BOS to MKE compared with the rest of the country?
80.5% of flights arrive on time here against a national 77.6%, a difference of 3 points in its favour. That is worth a B− on this site's grading scale.
What time of day has the fewest delays on BOS to MKE?
The 5am–8am departure window is the strongest at 92.7% on time. The 5pm–8pm window is the weakest at 62.6%, 30 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 BOS to MKE?
December is the weakest month at 65.6% on time, compared with 92.4% in June. Across the year that is 27 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 BOS — the return legseparate record
- Boston Logan International (BOS) delay statistics
- JetBlue Airways on BOS to MKE83.0%
- Republic Airways on BOS to MKE80.8%
- BOS to DCA, a related route74.0%
- ORD to MKE, a related route64.1%
- BOS to ORD, a related route72.7%
- JetBlue Airways on-time record83.0%
- Republic Airways on-time record80.8%
- Delta Air Lines on-time record50.0%
- The US routes with the most cancellations
- Why the first flight of the morning is statistically safest
Direction matters. BOS to MKE and MKE to BOS are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Embed BOS to MKE’s on-time badge on your site
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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.