Route reliability record
BWI→BOS
Baltimore to Boston
- Flights
- 3,540
- Period
- September 2025 to August 2026
- Distance
- 369 mi
- Carriers
- 3
This route sits in the middle of the pack with a C−. Close to three flights in four arrive on time by the DOT's definition, 3 points worse than the national rate of 77.3%. The late ones land about an hour behind schedule. That rests on 3,540 BWI to BOS flights, of which Republic Airways flew 1,099 at 80.5% on time.
Best time to fly BWI to BOS: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 94.3% of the time and Saturday flights 81.2%, against 74.1% for the route overall.
The US average over the same twelve months is 77.3%, 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
74.1%
Arrivals under 15 minutes late, of 3,421 completed flights
Avg delay
67 min
Across delayed arrivals only, not all flights
Cancelled
3.16%
National rate is 1.89%
Best carrier
Republic
80.5% on time across 1,099 flights
These figures cover 3,540 flights between September 2025 and August 2026. Beyond the headline rate, 9.5% 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 BWI to BOS
The choice of carrier is not cosmetic here. Republic Airways arrives on time 80.5% of the time; Southwest Airlines manages 71.1%. Sample sizes sit next to every figure, because a two-point gap across 2,415 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Spirit Airlinesthin sample | 26 | 80.8% | 35 min | 0.00% | B+ |
| Republic Airways | 1,099 | 80.5% | 85 min | 4.09% | B− |
| Southwest Airlines | 2,415 | 71.1% | 61 min | 2.77% | C |
Republic Airways cancels 4.1% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.
Flight by flight
Flights on BWI to BOS
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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Best ways to make this trip
The most reliable ways to fly Baltimore to Boston
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 4 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. BWI → MHTBaltimore to Manchester | Southwest Airlines | 83.0% | 84.2% | 1.39% | 5am–8am, Wed | — |
| 2. BWI → PVDBaltimore to Providence | Southwest Airlines | 77.8% | 79.6% | 2.28% | 5am–8am, Wed | — |
| 3. BWI → BOSBaltimore to Boston | Republic Airways | 77.2% | 80.5% | 4.09% | 5am–8am, Sat | YX 5703 10:54 |
| 4. IAD → BOSWashington to Boston | United Airlines | 75.5% | 77.1% | 2.07% | 8am–11am, Sat (route) | UA 641 08:35 |
| 5. DCA → PVDWashington to Providence | American Airlines | 74.4% | 77.0% | 3.33% | 8am–11am, Tue | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
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 41 points, against 9 points between the best and worst carrier.
- 5am–8am523 flights94.3%
- 8am–11am714 flights90.0%
- 11am–2pm588 flights73.0%
- 2pm–5pm649 flights62.1%
- 5pm–8pm462 flights53.8%
- 8pm–5am604 flights66.3%
Scale runs 45% to 100%.
The 5pm–8pm window is where this operation falls apart: 53.8% on time, against 94.3% 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 714 flights scheduled in it.
Explore
Filter BWI 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 BWI to BOS, the best departure window is 5am–8am at 94.3% on time and the worst is 5pm–8pm at 53.8%, a wide gap of 40.5 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am94.3%
- 8–11am90.0%
- 11am–2pm73.0%
- 2–5pm62.1%
- 5–8pm53.8%
- 8pm–5am66.3%
best all US flightsScale 45% to 100%.
Across the year
When delays peak on this route
This route's year swings by 25 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.
November is the best month on the calendar at 85.1% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. August was the busiest month here, with 341 flights.
Across the week, Saturday is the strongest day at 81.2% on time and Sunday the weakest at 67.1%, a spread of 14 points.
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 59,000 reported delay minutes.
- 40%National Airspace System
- 30%Carrier
- 26%Late-arriving aircraft
- 4%Extreme weather
- 0%Security
40% 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 23,000 minutes out of 59,000, against a national NAS share of 21%. The split is drawn from 59,029 reported delay minutes.
Cancellations run at 3.16%, 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
9.5% 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.
At 369 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 5am–8am window matters as much as it does.
The return leg is a different operation and performs like one: it runs 78.3% on time across 3,536 flights, 4 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 4 points of difference.
The sample behind these figures is 3,540 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 BOS after this flight
What to do with this
Booking this route
Put together: the delay figures matter less here than the 3.16% 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. 3,421 completed flights over 12 months sit behind that.
Common questions
BWI to BOS questions
How often is BWI to BOS delayed?
About 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 25.9% of the 3,540 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on BWI to BOS?
Republic Airways leads at 80.5% on time across 1,099 flights. Southwest Airlines is at the other end on 71.1%, a gap of 9 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on BWI to BOS?
The 5am–8am departure window is the strongest at 94.3% on time. The 5pm–8pm window is the weakest at 53.8%, 41 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 BWI to BOS?
September is the weakest month at 60.2% on time, compared with 85.1% in November. Across the year that is 25 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 BWI — the return legseparate record
- Baltimore/Washington International Thurgood Marshall (BWI) delay statistics
- Boston Logan International (BOS) delay statistics
- Republic Airways on BWI to BOS80.5%
- Southwest Airlines on BWI to BOS71.1%
- BWI to ATL, a related route79.9%
- DCA to BOS, a related route70.1%
- BWI to MCO, a related route75.5%
- Spirit Airlines on-time record80.8%
- Republic Airways on-time record80.5%
- Southwest Airlines on-time record71.1%
- The US routes with the most cancellations
- What a cancellation rate actually tells you (and what it hides)
Direction matters. BWI to BOS and BOS to BWI 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.