Boston, MA · departure reliability
BOS
Boston Logan International
- Departures
- 144,174
- Period
- September 2025 to August 2026
- Carriers
- 11
- US rank
- #12 by volume
Boston
Boston Logan International 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 a little over an hour behind schedule. That rests on 144,174 flights, of which Allegiant Air flew 586 at 82.1% on time.
Allegiant Air is the most reliable of the eleven carriers covered here at 82.1% on time across 586 flights.
Key figures
On time
74.6%
Departures arriving under 15 minutes late at their destination
Avg delay
73 min
Across delayed flights only
Cancelled
3.05%
National rate is 1.89%
Best carrier
Allegiant
82.1% on time here
These figures cover 144,000 flights between September 2025 and August 2026. Beyond the headline rate, 10.2% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
Carrier by carrier
Which airlines run best out of BOS
The choice of carrier is not cosmetic here. Allegiant Air arrives on time 82.1% of the time; Spirit Airlines manages 61.6%. Sample sizes sit next to every figure, because a two-point gap across 1,737 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| JetBlue Airways | 37,517 | 70.1% | 71 min | 3.41% | C− |
| Republic Airways | 34,798 | 77.2% | 68 min | 4.38% | B− |
| Delta Air Lines | 26,567 | 76.0% | 73 min | 2.16% | B |
| American Airlines | 17,138 | 78.2% | 93 min | 2.54% | B |
| United Airlines | 13,042 | 77.7% | 78 min | 1.92% | B |
| Southwest Airlines | 7,340 | 69.3% | 62 min | 1.66% | C |
| Alaska Airlines | 2,420 | 71.4% | 57 min | 1.36% | C |
| Envoy Air | 2,055 | 79.1% | 86 min | 2.29% | B |
| Spirit Airlines | 1,737 | 61.6% | 80 min | 5.87% | D− |
| Frontier Airlines | 926 | 68.0% | 65 min | 1.84% | C |
| Allegiant Air | 586 | 82.1% | 79 min | 0.68% | B+ |
Spirit Airlines cancels 5.9% 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.
Route by route
Busiest routes out of BOS
Route-level records vary far more than the airport average. These are the 25 busiest departures from BOS, each with its own on-time rate against the airport-wide 74.6%.
| Route | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| BOS to DCA · Washington | 9,105 | 72.6% | 72 min | 4.11% | C− |
| BOS to ORD · Chicago | 7,860 | 71.9% | 87 min | 2.98% | C |
| BOS to LGA · New York | 7,442 | 76.2% | 78 min | 6.40% | B− |
| BOS to JFK · New York | 5,614 | 74.2% | 71 min | 5.58% | C− |
| BOS to ATL · Atlanta | 5,050 | 76.8% | 72 min | 2.24% | B |
| BOS to PHL · Philadelphia | 5,036 | 76.0% | 89 min | 3.46% | B− |
| BOS to SFO · San Francisco | 4,817 | 69.2% | 66 min | 1.58% | C |
| BOS to LAX · Los Angeles | 4,794 | 73.7% | 79 min | 1.81% | C |
| BOS to MCO · Orlando | 4,605 | 69.5% | 77 min | 3.17% | C− |
| BOS to CLT · Charlotte | 4,009 | 82.0% | 81 min | 2.64% | B |
| BOS to EWR · Newark | 3,860 | 75.7% | 82 min | 4.51% | B− |
| BOS to DEN · Denver | 3,847 | 75.7% | 62 min | 1.38% | B |
| BOS to DFW · Dallas-Fort Worth | 3,692 | 77.4% | 88 min | 3.09% | B− |
| BOS to BWI · Baltimore | 3,536 | 78.3% | 67 min | 2.91% | B |
| BOS to MIA · Miami | 3,368 | 78.0% | 78 min | 2.17% | B |
| BOS to FLL · Fort Lauderdale | 3,306 | 66.8% | 72 min | 3.78% | C− |
| BOS to BNA · Nashville | 2,939 | 68.8% | 70 min | 2.55% | C |
| BOS to RDU · Raleigh | 2,848 | 75.5% | 78 min | 2.95% | B |
| BOS to TPA · Tampa | 2,780 | 74.4% | 70 min | 3.13% | C− |
| BOS to DTW · Detroit | 2,575 | 75.7% | 78 min | 2.80% | B |
| BOS to SEA · Seattle | 2,555 | 70.1% | 55 min | 1.49% | C |
| BOS to RSW · Fort Myers | 2,167 | 70.4% | 66 min | 2.77% | C |
| BOS to PIT · Pittsburgh | 2,163 | 75.6% | 70 min | 3.79% | B− |
| BOS to CVG · Cincinnati | 2,060 | 78.9% | 64 min | 2.91% | B |
| BOS to PBI · West Palm Beach | 2,039 | 65.6% | 72 min | 3.48% | C− |
Departure window
The best time of day to leave BOS
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 30 points, against 20 points between the best and worst carrier.
- 5am–8am28,547 flights87.9%
- 8am–11am30,145 flights82.9%
- 11am–2pm22,383 flights77.1%
- 2pm–5pm25,401 flights68.7%
- 5pm–8pm25,550 flights61.1%
- 8pm–5am12,148 flights58.1%
Scale runs 50% to 95%.
The 8pm–5am window is where this operation falls apart: 58.1% on time, against 87.9% 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 30,145 flights scheduled in it.
Explore
Filter BOS departures 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 departures from Boston (BOS), the best departure window is 5am–8am at 87.9% on time and the worst is 8pm–5am at 58.1%, a wide gap of 29.8 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am87.9%
- 8–11am82.9%
- 11am–2pm77.1%
- 2–5pm68.7%
- 5–8pm61.1%
- 8pm–5am58.1%
best all US flightsScale 50% to 95%.
Across the year
When BOS runs late
Twelve months, one bar each, drawn from the same 144,174 flights. The strip shows how much of BOS's record is set by the calendar rather than by the operation.
December is the weak month at 68.7% on time, against 79.4% in May. 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 13,277 flights.
Across the week, Wednesday is the strongest day at 78.6% on time and Sunday the weakest at 69.0%, a spread of 10 points.
BOS month by month
From Europe
Transatlantic routes into BOS
21 European airports send scheduled passenger flights to BOS, 26,820 flights a year in both directions by the DOT's international count. The DOT keeps no delay record for international flights; the UK routes carry the CAA's departure punctuality, and every route sets its departure airport's EUROCONTROL figures beside BOS's own record above.
- LHR to BOS · London5,370 flights
- CDG to BOS · Paris2,530 flights
- DUB to BOS · Dublin2,476 flights
- AMS to BOS · Amsterdam2,230 flights
- LIS to BOS · Lisbon1,889 flights
- MAD to BOS · Madrid1,650 flights
- KEF to BOS · Reykjavík1,377 flights
- FRA to BOS · Frankfurt1,167 flights
- ZRH to BOS · Zurich1,142 flights
- FCO to BOS · Rome1,003 flights
- BCN to BOS · Barcelona917 flights
- SNN to BOS · Shannon753 flights
Delay causes
Why BOS gets delayed
Late-arriving aircraft accounts for 43% of the 2.59 million delay minutes carriers reported here, and the remaining four split what is left.
- 43%Late-arriving aircraft
- 28%Carrier
- 27%National Airspace System
- 2%Extreme weather
- 0%Security
43% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 2.59 million reported delay minutes here, that single category outweighs weather by 17 to one. The split is drawn from 2,592,469 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 87.9% on time here.
Cancellations run at 3.05%, against 1.89% nationally. That is roughly 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.
10.2% 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.
144,174 flights sit behind these numbers, which is a large enough sample that the headline rate is not moving on noise. Where a sub-group falls below 30 flights the site shows a dash instead of a percentage.
What to do with this
Flying out of BOS
Put together: the delay figures matter less here than the 3.05% cancellation rate. A late arrival costs you a little over 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. 139,387 completed flights over 12 months sit behind that.
Common questions
BOS delay questions
How often is Boston (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 25.4% of the 144,174 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on Boston (BOS)?
Allegiant Air leads at 82.1% on time across 586 flights. Spirit Airlines is at the other end on 61.6%, a gap of 20 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 Boston (BOS)?
The 5am–8am departure window is the strongest at 87.9% on time. The 8pm–5am window is the weakest at 58.1%, 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 Boston (BOS)?
December is the weakest month at 68.7% on time, compared with 79.4% in May. Across the year that is 11 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 DCA — Washington72.6%
- BOS to ORD — Chicago71.9%
- BOS to LGA — New York76.2%
- BOS to JFK — New York74.2%
- BOS to ATL — Atlanta76.8%
- BOS to PHL — Philadelphia76.0%
- JetBlue Airways on-time record70.1%
- Republic Airways on-time record77.2%
- Delta Air Lines on-time record76.0%
- American Airlines on-time record78.2%
- Why the first flight of the morning is statistically safest
- Air traffic control delays, airport by airport
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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.