Route reliability record
BOS→MKE
Boston to Milwaukee
- Flights
- 737
- Period
- September 2025 to August 2026
- Distance
- 860 mi
- Carriers
- 3
This route carries a cancellation problem, not just a delay problem: 3.5% of scheduled flights never operate, against 1.9% nationally. Of the ones that do fly, more than 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 737 BOS to MKE flights, with a median arrival 9 minutes early.
Best time to fly BOS to MKE: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 90.1% of the time and Wednesday flights 87.4%, against 82.7% for the route overall.
Set against the rest of the country, this route's record is 5 points better than the US average of 77.3%. That gap is worth roughly 54 fewer late arrivals for every thousand flights.
Key figures
On time
82.7%
Arrivals under 15 minutes late, of 710 completed flights
Avg delay
58 min
Across delayed arrivals only, not all flights
Cancelled
3.53%
National rate is 1.89%
Best carrier
Republic
82.2% on time across 540 flights
These figures cover 737 flights between September 2025 and August 2026. The median arrival is 9 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.
Fare search by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
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 | 87.6% | 58 min | 1.16% | A |
| Republic Airways | 540 | 82.2% | 54 min | 4.26% | B− |
| Delta Air Linesthin sample | 25 | 58.3% | 92 min | 4.00% | D− |
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.
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
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 29 points, against half a point between the best and worst carrier.
- 5am–8am103 flights90.1%
- 8am–11am234 flights88.6%
- 11am–2pm27 flights—
- 2pm–5pm229 flights80.6%
- 5pm–8pm94 flights61.5%
- 8pm–5am50 flights88.9%
Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 61.5% on time, against 90.1% 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 234 flights scheduled in it.
Explore
Filter BOS 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 BOS to MKE, the best departure window is 5am–8am at 90.1% on time and the worst is 5pm–8pm at 61.5%, a wide gap of 28.6 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am90.1%
- 8–11am88.6%
- 11am–2pm—
- 2–5pm80.6%
- 5–8pm61.5%
- 8pm–5am88.9%
best all US flightsScale 55% to 95%. Cells under 30 flights show a dash.
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. July was the busiest month here, with 84 flights.
Across the week, Wednesday is the strongest day at 87.4% on time and Friday the weakest at 78.7%, a spread of 9 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 43% of the 7,107 delay minutes carriers reported here, and the remaining four split what is left.
- 43%Late-arriving aircraft
- 36%Carrier
- 20%National Airspace System
- 1%Extreme weather
43% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 7,107 reported delay minutes here, that single category outweighs weather by 39 to one. The split is drawn from 7,107 reported delay minutes.
The largest share of delay minutes, 36%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 2,550 of the 7,107 delay minutes reported here.
Cancellations run at 3.53%, 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
6.1% of arrivals land an hour or more late, close to the national 8.3%, so 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.
The return leg is a different operation and performs like one: it runs 72.1% on time across 736 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. 737 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 3.53% 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. 710 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 six arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 17.3% of the 737 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
How reliable is BOS to MKE compared with the rest of the country?
82.7% of flights arrive on time here against a national 77.3%, a difference of 5 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 90.1% on time. The 5pm–8pm window is the weakest at 61.5%, 29 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
- Milwaukee Mitchell International (MKE) delay statistics
- JetBlue Airways on BOS to MKE87.6%
- Republic Airways on BOS to MKE82.2%
- BOS to DCA, a related route72.6%
- ORD to MKE, a related route64.3%
- BOS to ORD, a related route71.9%
- JetBlue Airways on-time record87.6%
- Republic Airways on-time record82.2%
- Delta Air Lines on-time record58.3%
- 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
Paste this into a web page. The badge shows the current on-time rate, cancellation rate and grade, and updates every month. Preview it, or build a badge for another route or airport.
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.