Carrier performance at one airport
UA→BOS
United Airlines at Boston Logan International
- Departures
- 12,811
- Period
- June 2025 to May 2026
- Routes
- 7
- Rank here
- #3 of 11
United Airlines at Boston lands a B, about a point better than the national rate of 77.4%. About one flight in five 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 12,811 flights, of which Allegiant Air flew 663 at 85.9% on time.
Measured against the airport rather than the country, United Airlines runs 3 points ahead of the 75.4% 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
78.6%
12,544 completed departures
Avg delay
76 min
Across delayed flights only
Cancelled
1.85%
At BOS, this carrier only
Rank here
#3
Of 11 carriers clearing the floor at BOS
These figures cover 13,000 flights between June 2025 and May 2026. Beyond the headline rate, 8.1% 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 85.9% of the time; Spirit Airlines manages 66.0%. Sample sizes sit next to every figure, because a two-point gap across 2,654 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Allegiant Air | 663 | 85.9% | 85 min | 0.45% | A+ |
| Envoy Air | 1,992 | 79.2% | 75 min | 2.06% | B |
| United Airlines (this page) | 12,811 | 78.6% | 76 min | 1.85% | B |
| American Airlines | 16,729 | 77.7% | 92 min | 2.58% | B |
| Republic Airways | 33,245 | 77.5% | 67 min | 3.94% | B− |
| Delta Air Lines | 26,395 | 76.5% | 73 min | 1.97% | B |
| JetBlue Airways | 37,535 | 72.1% | 69 min | 2.40% | C |
| Southwest Airlines | 7,153 | 71.7% | 62 min | 1.54% | C |
| Frontier Airlines | 935 | 70.6% | 62 min | 1.71% | C |
| Alaska Airlines | 2,546 | 70.2% | 54 min | 1.10% | C |
| Spirit Airlines | 2,654 | 66.0% | 78 min | 4.37% | C− |
Spirit Airlines cancels 4.4% 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 United Airlines flies from BOS
United Airlines operates 7 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 EWR · Newark | 2,671 | 75.5% | 85 min | 3.37% | B− |
| BOS to ORD · Chicago | 2,631 | 74.3% | 82 min | 1.79% | C |
| BOS to DEN · Denver | 1,913 | 82.4% | 63 min | 1.05% | B |
| BOS to SFO · San Francisco | 1,816 | 79.4% | 67 min | 1.05% | B |
| BOS to IAH · Houston | 1,576 | 82.5% | 68 min | 1.59% | B |
| BOS to IAD · Washington | 1,487 | 82.4% | 76 min | 1.88% | B |
| BOS to LAX · Los Angeles | 716 | 77.8% | 67 min | 1.12% | 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 34 points, against 20 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am2,904 flights91.2%
- 8am–11am2,708 flights88.5%
- 11am–2pm1,978 flights83.2%
- 2pm–5pm2,427 flights70.3%
- 5pm–8pm2,264 flights60.4%
- 8pm–5am530 flights56.9%
Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 56.9% on time, against 91.2% 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.
Across the year
Seasonal pattern
July is the worst month at 71.9% on time, 15 points below April, the best at 86.5%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck.
Delay causes
What holds this operation up
- 41%Late-arriving aircraft
- 38%National Airspace System
- 19%Carrier
- 3%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 203,000 reported delay minutes here, that single category outweighs weather by 16 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.
Cancellations sit at 1.85% against a national 1.80%, which is ordinary. Diversions add another 0.23%.
8.1% of arrivals land an hour or more late, close to the national 8.2%. 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.
12,811 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. April runs 86.5% on time and July 71.9%, a swing of 15 points. If the dates move at all, move them out of July before you think about anything else.
Common questions
United Airlines at BOS
How often is United Airlines at BOS delayed?
About one flight in five arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 21.4% of the 12,811 flights in this analysis, against 22.6% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on United Airlines at BOS?
Allegiant Air leads at 85.9% on time across 663 flights. Spirit Airlines is at the other end on 66.0%, 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 United Airlines at BOS?
The 5am–8am departure window is the strongest at 91.2% on time. The 8pm–5am window is the weakest at 56.9%, 34 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 July delays on United Airlines at BOS?
July is the weakest month at 71.9% on time, compared with 86.5% in April. Across the year that is 15 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, June 2025 to May 2026. Updated monthly. How this data is collected.