Carrier performance at one airport
DL→BOS
Delta Air Lines at Boston Logan International
- Departures
- 26,419
- Period
- July 2025 to June 2026
- Routes
- 25
- Rank here
- #6 of 11
Delta Air Lines at Boston lands a B, about a point worse than the national rate of 77.6%. About one flight in four arrive 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 26,419 flights, of which Allegiant Air flew 633 at 84.9% on time.
Measured against the airport rather than the country, Delta Air Lines runs about a point ahead of the 75.7% weighted average across all carriers at BOS. That is the comparison worth making: every operator here works the same runways, the same airspace and the same weather.
Key figures
On time
76.8%
25,807 completed departures
Avg delay
73 min
Across delayed flights only
Cancelled
2.03%
At BOS, this carrier only
Rank here
#6
Of 11 carriers clearing the floor at BOS
These figures cover 26,000 flights between July 2025 and June 2026. Beyond the headline rate, 8.7% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Against the competition
Every carrier at BOS, ranked
The choice of carrier is not cosmetic here. Allegiant Air arrives on time 84.9% of the time; Spirit Airlines manages 65.3%. Sample sizes sit next to every figure, because a two-point gap across 2,325 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Allegiant Air | 633 | 84.9% | 86 min | 0.47% | B+ |
| Envoy Air | 2,013 | 79.9% | 74 min | 2.24% | B |
| United Airlines | 12,917 | 78.6% | 76 min | 1.90% | B |
| American Airlines | 16,933 | 78.3% | 91 min | 2.56% | B |
| Republic Airways | 33,650 | 78.1% | 67 min | 3.88% | B− |
| Delta Air Lines (this page) | 26,419 | 76.8% | 73 min | 2.03% | B |
| JetBlue Airways | 37,487 | 72.0% | 70 min | 2.51% | C |
| Southwest Airlines | 7,197 | 71.3% | 63 min | 1.53% | C |
| Alaska Airlines | 2,486 | 71.2% | 53 min | 1.17% | C |
| Frontier Airlines | 931 | 70.3% | 60 min | 1.83% | C |
| Spirit Airlines | 2,325 | 65.3% | 79 min | 4.82% | C− |
Spirit Airlines cancels 4.8% 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
Where Delta Air Lines flies from BOS
Delta Air Lines operates 25 routes out of BOS with enough volume to report. Route records inside one carrier at one airport still spread widely, because a short shuttle and a transcontinental have very different exposure to a late inbound.
| Route | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| BOS to ATL · Atlanta | 3,662 | 82.1% | 75 min | 1.77% | B |
| BOS to MSP · Minneapolis | 1,851 | 83.1% | 63 min | 1.19% | B |
| BOS to DTW · Detroit | 1,712 | 79.6% | 77 min | 2.04% | B |
| BOS to RDU · Raleigh | 1,437 | 77.6% | 86 min | 2.44% | B |
| BOS to MCO · Orlando | 1,257 | 75.4% | 80 min | 2.15% | B |
| BOS to LAX · Los Angeles | 1,228 | 75.2% | 76 min | 1.71% | B |
| BOS to TPA · Tampa | 1,168 | 75.7% | 78 min | 1.97% | B |
| BOS to SLC · Salt Lake City | 1,083 | 77.8% | 68 min | 1.20% | B |
| BOS to SEA · Seattle | 1,006 | 71.6% | 55 min | 1.59% | C |
| BOS to AUS · Austin | 988 | 74.9% | 93 min | 2.63% | C |
| BOS to ORD · Chicago | 962 | 65.2% | 75 min | 3.12% | C− |
| BOS to SFO · San Francisco | 898 | 71.8% | 63 min | 1.45% | C |
| BOS to MIA · Miami | 890 | 72.1% | 76 min | 2.70% | C |
| BOS to FLL · Fort Lauderdale | 885 | 69.5% | 78 min | 3.05% | C− |
| BOS to DFW · Dallas-Fort Worth | 861 | 70.0% | 79 min | 2.21% | C |
| BOS to LAS · Las Vegas | 593 | 77.9% | 58 min | 1.35% | B |
| BOS to PBI · West Palm Beach | 591 | 70.7% | 74 min | 2.37% | C |
| BOS to RSW · Fort Myers | 582 | 77.5% | 64 min | 1.55% | B |
| BOS to LGA · New York | 543 | 90.2% | 126 min | 4.24% | A− |
| BOS to BNA · Nashville | 533 | 71.6% | 88 min | 0.75% | C+ |
| BOS to PHX · Phoenix | 428 | 69.1% | 57 min | 1.87% | C |
| BOS to DEN · Denver | 400 | 81.4% | 46 min | 1.75% | B |
| BOS to SJU · San Juan | 398 | 76.0% | 57 min | 1.51% | B |
| BOS to CHS · Charleston | 390 | 78.0% | 73 min | 2.31% | B |
| BOS to MSY · New Orleans | 374 | 84.1% | 59 min | 2.14% | B |
Departure window
Best time of day for this operation
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 26 points, against 20 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am7,270 flights86.6%
- 8am–11am4,390 flights82.4%
- 11am–2pm4,021 flights80.2%
- 2pm–5pm4,149 flights68.2%
- 5pm–8pm4,649 flights67.7%
- 8pm–5am1,940 flights60.1%
Scale runs 50% to 90%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 60.1% on time, against 86.6% 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 5am–8am window is the busiest, with 7,270 flights scheduled in it.
Across the year
Seasonal pattern
December is the weak month at 66.9% on time, against 84.0% in August. 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. May was the busiest month here, with 2,392 flights.
Delay causes
What holds this operation up
- 38%Late-arriving aircraft
- 37%Carrier
- 24%National Airspace System
- 1%Extreme weather
- 0%Security
38% 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 438,000 reported delay minutes here, that single category outweighs weather by 25 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 438,047 reported delay minutes.
Cancellations sit at 2.03% against a national 1.81%, which is ordinary. Diversions add another 0.29%.
8.7% 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 are the a little over an hour kind, which a normal layover absorbs.
26,419 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.
Put together: the calendar is the biggest lever here, not the carrier or the hour. August runs 84.0% on time and December 66.9%, a swing of 17 points. If the dates move at all, move them out of December before you think about anything else. 25,807 completed flights over 12 months sit behind that.
Common questions
Delta Air Lines at BOS
How often is Delta Air Lines at BOS delayed?
About one flight in four arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 23.2% of the 26,419 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on Delta Air Lines at BOS?
Allegiant Air leads at 84.9% on time across 633 flights. Spirit Airlines is at the other end on 65.3%, 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 Delta Air Lines at BOS?
The 5am–8am departure window is the strongest at 86.6% on time. The 8pm–5am window is the weakest at 60.1%, 26 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 Delta Air Lines at BOS?
December is the weakest month at 66.9% on time, compared with 84.0% in August. Across the year that is 17 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
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.