Carrier route record
UALAX→BOS
United Airlines · Los Angeles to Boston
- Flights
- 716
- Period
- July 2025 to June 2026
- Share of route
- 15%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on LAX to BOS earns an A. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 9 points better than the national rate of 77.6%. When something does go wrong the average delay runs a little over an hour. That rests on 716 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 1,230 at 78.6% on time.
Set against the rest of the country, United's LAX to BOS record is 9 points better than the US average of 77.6%. That gap is worth roughly 94 fewer late arrivals for every thousand flights.
Key figures
On time
87.0%
Arrivals under 15 minutes late, of 707 completed flights
Avg delay
70 min
Across delayed arrivals only, not all flights
Cancelled
1.12%
National rate is 1.81%
Whole route
78.4%
Every carrier on LAX to BOS, 4,718 flights
These figures cover 716 flights between July 2025 and June 2026. The median arrival is 13 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
Carrier by carrier
United against every carrier on LAX to BOS
United flew 716 of the 4,718 flights on LAX to BOS, about 15% of it. Its 87.0% on time is 9 points better than the route as a whole, which runs 78.4%. Ranked by on-time rate it is first of four carriers on the route, where the range runs from United at 87.0% to JetBlue at 75.8%.
The three carriers here are closely matched: 3 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines (this page) | 716 | 87.0% | 70 min | 1.12% | A |
| Delta Air Lines | 1,230 | 78.6% | 86 min | 1.71% | B |
| American Airlines | 1,146 | 76.5% | 91 min | 1.31% | B |
| JetBlue Airways | 1,626 | 75.8% | 73 min | 1.41% | B |
No carrier stands out. Delta tops the table at 78.6%, 3 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
United flight numbers on LAX to BOS
Departure window
When United runs best on this route
Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 716 flights.
- 5am–8am—
- 8am–11am365 flights83.4%
- 11am–2pm—
- 2pm–5pm—
- 5pm–8pm—
- 8pm–5am351 flights90.8%
Scale runs 75% to 95%. Rows with fewer than 30 flights show a dash.
The overnight block holds up unusually well at 90.8% on time across 351 flights. Red-eyes fly into empty airspace and empty gates, and they are the first rotation of the aircraft's day rather than the last. The 8am–11am window is the busiest, with 365 flights scheduled in it.
Across the year
United on LAX to BOS through the year
Delays peak in March, when the on-time rate falls to 76.3%. January is the strongest month at 94.5%. Moving a flexible trip across that boundary buys 18 points. November was the busiest month here, with 63 flights.
Across the week, Tuesday is the strongest day at 92.3% on time and Friday the weakest at 82.9%. 9 points is a smaller lever than departure hour, but it is free.
Delay causes
Why United runs late on this route
One category carries most of the weight here. National Airspace System accounts for 52% of the 6,467 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 52%National Airspace System
- 34%Late-arriving aircraft
- 14%Carrier
- 1%Extreme weather
52% 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 3,338 minutes out of 6,467, against a national NAS share of 21%. The split is drawn from 6,467 reported delay minutes.
Cancellations sit at 1.12% against a national 1.81%, which is ordinary. Diversions add another 0.14%.
Connections and stage length
What a delay here costs
Badly late arrivals are rare here: only 4.4% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
At 2,611 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg is a different operation and performs like one: it runs 76.8% on time across 716 flights, 10 points below 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 10 points of difference.
One caution: this is a thin sample. 716 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking United on LAX to BOS
Put together: treat all of this as provisional. 716 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 87.0% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 707 completed flights over 12 months sit behind that.
Related
Where to go next
- LAX to BOS, every carrier
- United on BOS to LAX, the return leg
- Delta Air Lines on LAX to BOS78.6%
- American Airlines on LAX to BOS76.5%
- JetBlue Airways on LAX to BOS75.8%
- United Airlines network-wide record
- Los Angeles International (LAX) delay statistics
- Boston Logan International (BOS) delay statistics
- Why the first flight of the morning is statistically safest
- Worst months to fly in the US, ranked by the data
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.