Carrier route record
DLSEA→SAN
Delta Air Lines · Seattle to San Diego
- Flights
- 1,700
- Period
- July 2025 to June 2026
- Share of route
- 37%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.
Delta on SEA to SAN lands a B+, 5 points better than the national rate of 77.6%. About one flight in six arrives 15 minutes late or worse, and those flights are late by roughly 55 minutes on average. That is a workable record, not a spotless one. That rests on 1,700 flights, with a median arrival 7 minutes early.
Set against the rest of the country, Delta's SEA to SAN record is 5 points better than the US average of 77.6%. That gap is worth roughly 50 fewer late arrivals for every thousand flights.
Key figures
On time
82.6%
Arrivals under 15 minutes late, of 1,676 completed flights
Avg delay
53 min
Across delayed arrivals only, not all flights
Cancelled
0.94%
National rate is 1.81%
Whole route
77.3%
Every carrier on SEA to SAN, 4,584 flights
These figures cover 1,700 flights between July 2025 and June 2026. The median arrival is 7 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
Delta against every carrier on SEA to SAN
Delta flew 1,700 of the 4,584 flights on SEA to SAN, about 37% of it. Its 82.6% on time is 5 points better than the route as a whole, which runs 77.3%. Ranked by on-time rate it is number two of four carriers on the route, where the range runs from SkyWest at 100.0% to Southwest at 55.9%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlinesthin sample | 1 | 100.0% | — | 0.00% | A+ |
| Delta Air Lines (this page) | 1,700 | 82.6% | 53 min | 0.94% | B+ |
| Alaska Airlines | 2,765 | 75.0% | 44 min | 1.45% | B |
| Southwest Airlinesthin sample | 118 | 55.9% | 41 min | 0.00% | D+ |
Flight by flight
Delta flight numbers on SEA to SAN
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 16 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am353 flights91.7%
- 8am–11am339 flights82.7%
- 11am–2pm346 flights83.0%
- 2pm–5pm303 flights78.8%
- 5pm–8pm247 flights75.8%
- 8pm–5am112 flights77.3%
Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 91.7% of the time, against 75.8% for the evening window. That is 16 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 353 flights scheduled in it.
Across the year
Delta on SEA to SAN through the year
September is the best month on the calendar at 91.0% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. May was the busiest month here, with 150 flights.
Across the week, Tuesday is the strongest day at 87.0% on time and Thursday the weakest at 77.5%. 10 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Delta runs late on this route
One category carries most of the weight here. Carrier accounts for 47% of the 16,000 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.
- 47%Carrier
- 28%National Airspace System
- 21%Late-arriving aircraft
- 4%Extreme weather
The largest share of delay minutes, 47%, 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 7,278 of the 16,000 delay minutes reported here. The split is drawn from 15,584 reported delay minutes.
Cancellations sit at 0.94% against a national 1.81%, which is ordinary. Diversions add another 0.47%.
Connections and stage length
What a delay here costs
5.0% 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 roughly 55 minutes, which a normal layover absorbs.
The 1,050 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The return leg is a different operation and performs like one: it runs 87.3% on time across 1,700 flights, 5 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 5 points of difference.
The sample behind these figures is 1,700 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 SEA to SAN
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 91.0% on time and November 70.0%, a swing of 21 points. If the dates move at all, move them out of November before you think about anything else. 1,676 completed flights over 12 months sit behind that.
Related
Where to go next
- SEA to SAN, every carrier
- Delta on SAN to SEA, the return leg
- Alaska Airlines on SEA to SAN75.0%
- Southwest Airlines on SEA to SAN55.9%
- Delta Air Lines network-wide record
- Seattle-Tacoma International (SEA) delay statistics
- San Diego International (SAN) delay statistics
- The best time of day to fly, according to 7.04 million flight records
- 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.