Carrier route record
DLBOS→LAX
Delta Air Lines · Boston to Los Angeles
- Flights
- 1,228
- Period
- July 2025 to June 2026
- Share of route
- 26%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.
Delta on BOS to LAX 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 77.6%. The late ones land a little over an hour behind schedule. That rests on 1,228 flights. The strongest carrier on the route with a full sample, United Airlines, flew 716 at 76.8% on time.
United Airlines is the most reliable of the three carriers covered here at 76.8% on time across 716 flights.
Key figures
On time
75.2%
Arrivals under 15 minutes late, of 1,206 completed flights
Avg delay
76 min
Across delayed arrivals only, not all flights
Cancelled
1.71%
National rate is 1.81%
Whole route
74.9%
Every carrier on BOS to LAX, 4,713 flights
These figures cover 1,228 flights between July 2025 and June 2026. Beyond the headline rate, 8.0% 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
Delta against every carrier on BOS to LAX
Delta flew 1,228 of the 4,713 flights on BOS to LAX, about 26% of it. Its 75.2% on time is about level with the route as a whole at 74.9%. Ranked by on-time rate it is number two of four carriers on the route, where the range runs from United at 76.8% to American at 74.0%.
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 | 716 | 76.8% | 67 min | 1.12% | B |
| Delta Air Lines (this page) | 1,228 | 75.2% | 76 min | 1.71% | B |
| JetBlue Airways | 1,626 | 74.5% | 71 min | 1.41% | C |
| American Airlines | 1,143 | 74.0% | 91 min | 1.31% | C |
No carrier stands out. United tops the table at 76.8%, 3 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Delta flight numbers on BOS to LAX
Departure window
When Delta runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 17 points, against 3 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am361 flights79.4%
- 8am–11am94 flights79.6%
- 11am–2pm219 flights78.0%
- 2pm–5pm196 flights73.7%
- 5pm–8pm196 flights74.7%
- 8pm–5am162 flights62.1%
Scale runs 55% to 85%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 62.1% on time, against 79.6% for the 8am–11am 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 361 flights scheduled in it.
Across the year
Delta on BOS to LAX through the year
December is the weak month at 64.0% on time, against 88.2% 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. May was the busiest month here, with 119 flights.
Across the week, Tuesday is the strongest day at 78.4% on time and Monday the weakest at 71.6%. 7 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Delta runs late on this route
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 23,000 reported delay minutes.
- 41%Carrier
- 36%Late-arriving aircraft
- 21%National Airspace System
- 1%Extreme weather
36% 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 23,000 reported delay minutes here, that single category outweighs weather by 27 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 22,568 reported delay minutes.
The largest share of delay minutes, 41%, 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 9,273 of the 23,000 delay minutes reported here.
Cancellations sit at 1.71% against a national 1.81%, which is ordinary. Diversions add another 0.08%.
Connections and stage length
What a delay here costs
8.0% 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 last a little over an hour, 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 is a different operation and performs like one: it runs 78.6% on time across 1,230 flights, 3 points above 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 3 points of difference.
The sample behind these figures is 1,228 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 Delta on BOS to LAX
Put together: the calendar is the biggest lever here, not the carrier or the hour. August runs 88.2% on time and December 64.0%, a swing of 24 points. If the dates move at all, move them out of December before you think about anything else. 1,206 completed flights over 12 months sit behind that.
Related
Where to go next
- BOS to LAX, every carrier
- Delta on LAX to BOS, the return leg
- United Airlines on BOS to LAX76.8%
- JetBlue Airways on BOS to LAX74.5%
- American Airlines on BOS to LAX74.0%
- Delta Air Lines network-wide record
- Boston Logan International (BOS) delay statistics
- Los Angeles International (LAX) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
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.