Carrier performance at one airport
UA→BOS
United Airlines at Boston Logan International
- Departures
- 13,042
- Period
- September 2025 to August 2026
- Routes
- 7
- Rank here
- #4 of 11
United Airlines at Boston lands a B, level with the national rate of 77.3%. Roughly one flight in four arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That rests on 13,042 flights, of which Allegiant Air flew 586 at 82.1% on time.
Measured against the airport rather than the country, United Airlines runs 3 points ahead of the 74.6% 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
77.7%
12,762 completed departures
Avg delay
78 min
Across delayed flights only
Cancelled
1.92%
At BOS, this carrier only
Rank here
#4
Of 11 carriers clearing the floor at BOS
These figures cover 13,000 flights between September 2025 and August 2026. Beyond the headline rate, 8.8% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
Against the competition
Every carrier at BOS, ranked
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 |
|---|---|---|---|---|---|
| Allegiant Air | 586 | 82.1% | 79 min | 0.68% | B+ |
| Envoy Air | 2,055 | 79.1% | 86 min | 2.29% | B |
| American Airlines | 17,138 | 78.2% | 93 min | 2.54% | B |
| United Airlines (this page) | 13,042 | 77.7% | 78 min | 1.92% | B |
| Republic Airways | 34,798 | 77.2% | 68 min | 4.38% | B− |
| Delta Air Lines | 26,567 | 76.0% | 73 min | 2.16% | B |
| Alaska Airlines | 2,420 | 71.4% | 57 min | 1.36% | C |
| JetBlue Airways | 37,517 | 70.1% | 71 min | 3.41% | C− |
| Southwest Airlines | 7,340 | 69.3% | 62 min | 1.66% | C |
| Frontier Airlines | 926 | 68.0% | 65 min | 1.84% | C |
| Spirit Airlines | 1,737 | 61.6% | 80 min | 5.87% | D− |
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
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 ORD · Chicago | 2,791 | 74.5% | 86 min | 1.79% | C |
| BOS to EWR · Newark | 2,695 | 75.8% | 88 min | 3.53% | B− |
| BOS to SFO · San Francisco | 1,940 | 72.5% | 66 min | 1.19% | C |
| BOS to DEN · Denver | 1,884 | 82.5% | 70 min | 1.11% | B |
| BOS to IAH · Houston | 1,550 | 82.3% | 75 min | 1.29% | B |
| BOS to IAD · Washington | 1,450 | 83.3% | 78 min | 2.28% | B |
| BOS to LAX · Los Angeles | 731 | 76.8% | 71 min | 1.09% | B |
Flight by flight
United Airlines flight numbers from BOS
22 United Airlines flight numbers leaving BOS flew their main route often enough to have a record of their own. Grouped by destination.
- UA 414to DEN 12:2289.4%
- UA 647to DEN 07:4590.5%
- UA 662to DEN 09:4089.3%
- UA 800to DEN 16:5072.9%
- UA 2297to DEN 15:1085.1%
- UA 570to EWR 08:0089.4%
- UA 1833to EWR 06:0092.8%
- UA 2394to EWR 10:3087.1%
- UA 721to IAD 14:1576.6%
- UA 1734to IAD 05:4596.1%
- UA 2098to IAD 09:3089.7%
- UA 2136to IAD 19:2770.0%
- UA 226to IAH 07:2593.3%
- UA 1976to IAH 13:3788.5%
- UA 1015to ORD 18:2350.3%
- UA 1349to ORD 09:5086.0%
- UA 1414to ORD 06:0093.6%
- UA 1732to ORD 12:3083.8%
- UA 2040to ORD 16:2553.1%
- UA 1074to SFO 11:3577.8%
- UA 2400to SFO 18:1051.1%
- UA 2441to SFO 06:0084.4%
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.
- 5am–8am2,931 flights90.6%
- 8am–11am2,706 flights86.1%
- 11am–2pm2,001 flights83.0%
- 2pm–5pm2,378 flights71.3%
- 5pm–8pm2,370 flights59.6%
- 8pm–5am656 flights56.4%
Scale runs 50% to 95%.
The 8pm–5am window is where this operation falls apart: 56.4% on time, against 90.6% 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 2,931 flights scheduled in it.
Across the year
Seasonal pattern
August is the worst month at 67.4% on time, 19 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. August was the busiest month here, with 1,236 flights.
Delay causes
What holds this operation up
- 39%Late-arriving aircraft
- 39%National Airspace System
- 20%Carrier
- 2%Extreme weather
39% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 223,000 reported delay minutes here, that single category outweighs weather by 20 to one. The split is drawn from 223,112 reported delay minutes.
Cancellations sit at 1.92% against a national 1.89%, which is ordinary. Diversions add another 0.23%.
8.8% 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 a little over an hour, which a normal layover absorbs.
13,042 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 August 67.4%, a swing of 19 points. If the dates move at all, move them out of August before you think about anything else. 12,762 completed flights over 12 months sit behind that.
Common questions
United Airlines at BOS
How often is United Airlines at BOS delayed?
Roughly 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 22.3% of the 13,042 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 United Airlines at 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 United Airlines at BOS?
The 5am–8am departure window is the strongest at 90.6% on time. The 8pm–5am window is the weakest at 56.4%, 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 August delays on United Airlines at BOS?
August is the weakest month at 67.4% on time, compared with 86.5% in April. Across the year that is 19 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.