Route reliability record
BOS→LAX
Boston to Los Angeles
- Flights
- 4,655
- Period
- June 2025 to May 2026
- Distance
- 2,611 mi
- Carriers
- 4
This route sits in the middle of the pack with a B. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.4%. The late ones land a little over an hour behind schedule. That rests on 4,655 flights, of which United Airlines flew 716 at 77.8% on time.
United Airlines is the most reliable of the four carriers covered here at 77.8% on time across 716 flights.
Key figures
On time
75.9%
Arrivals under 15 minutes late, of 4,581 completed flights
Avg delay
80 min
Across delayed arrivals only, not all flights
Cancelled
1.40%
National rate is 1.80%
Best carrier
United
77.8% on time across 716 flights
These figures cover 4,655 flights between June 2025 and May 2026. Beyond the headline rate, 8.8% 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.
Carrier by carrier
Which airline is most reliable on BOS to LAX
The four carriers here are closely matched: 5 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 | 716 | 77.8% | 67 min | 1.12% | B |
| JetBlue Airways | 1,622 | 76.8% | 71 min | 1.42% | B |
| Delta Air Lines | 1,224 | 76.1% | 77 min | 1.63% | B |
| American Airlines | 1,093 | 73.3% | 102 min | 1.28% | C |
No carrier stands out. United tops the table at 77.8%, 5 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 23 points, against 5 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am1,014 flights85.3%
- 8am–11am1,024 flights80.4%
- 11am–2pm509 flights79.8%
- 2pm–5pm522 flights76.1%
- 5pm–8pm1,119 flights67.2%
- 8pm–5am467 flights62.4%
Scale runs 55% to 90%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 62.4% on time, against 85.3% 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
When delays peak on this route
This route's year swings by 23 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
December is the weak month at 62.1% on time, against 85.2% 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.
Across the week, Wednesday is the strongest day at 79.2% on time and Monday the weakest at 71.9%. 7 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Late-arriving aircraft accounts for 43% of the 88,000 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.
- 43%Late-arriving aircraft
- 35%Carrier
- 20%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. That is a cascade, and cascades start small and grow through the day. Across 88,000 reported delay minutes here, that single category outweighs weather by 19 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 largest share of delay minutes, 35%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 31,000 of the 88,000 delay minutes reported here.
Cancellations sit at 1.40% against a national 1.80%, which is ordinary. Diversions add another 0.19%.
Connections and stage length
What a delay here actually costs
8.8% 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.
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 runs 78.5% on time across 4,659 flights, within 3 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 4,655 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. August runs 85.2% on time and December 62.1%, a swing of 23 points. If the dates move at all, move them out of December before you think about anything else.
Common questions
BOS to LAX questions
How often is BOS to LAX 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 24.1% of the 4,655 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 BOS to LAX?
United Airlines leads at 77.8% on time across 716 flights. American Airlines is at the other end on 73.3%, a gap of 5 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 BOS to LAX?
The 5am–8am departure window is the strongest at 85.3% on time. The 8pm–5am window is the weakest at 62.4%, 23 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 BOS to LAX?
December is the weakest month at 62.1% on time, compared with 85.2% in August. Across the year that is 23 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
- LAX to BOS — the return legseparate record
- Boston Logan International (BOS) delay statistics
- Los Angeles International (LAX) delay statistics
- United Airlines on-time record77.8%
- JetBlue Airways on-time record76.8%
- Delta Air Lines on-time record76.1%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Direction matters. BOS to LAX and LAX to BOS are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, June 2025 to May 2026. Updated monthly. How this data is collected.