Carrier route record

DLSNA→SEA

Delta Air Lines · Santa Ana to Seattle

Flights: 954
Period: July 2025 to June 2026
Share of route: 24%
Carriers: 3

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.

Delta on SNA to SEA lands a B, 4 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 954 flights. The strongest carrier on the route with a full sample, Alaska Airlines, flew 2,606 at 87.5% on time.

The US average over the same twelve months is 77.6%, so there is little to separate Delta on SNA to SEA from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

81.2%

Arrivals under 15 minutes late, of 940 completed flights

Avg delay

73 min

Across delayed arrivals only, not all flights

Cancelled

1.26%

National rate is 1.81%

Whole route

85.7%

Every carrier on SNA to SEA, 3,965 flights

These figures cover 954 flights between July 2025 and June 2026. The median arrival is 11 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 SNA to SEA

Delta flew 954 of the 3,965 flights on SNA to SEA, about 24% of it. Its 81.2% on time is 5 points worse than the route as a whole, which runs 85.7%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from Alaska at 87.5% to Delta at 81.2%.

The two 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.

On-time performance by carrier on SNA to SEA
Airline	Flights	On time	Avg delay	Cancelled	Grade
Alaska Airlines	2,606	87.5%	50 min	1.34%	A
SkyWest Airlines	405	84.5%	40 min	0.25%	B+
Delta Air Lines (this page)	954	81.2%	73 min	1.26%	B

No carrier stands out. Alaska tops the table at 87.5%, 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 SNA to SEA

DL 210111:1587.6% · 256 flights

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 18 points, against 3 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am189 flights89.9%
8am–11am24 flights—
11am–2pm297 flights86.2%
2pm–5pm217 flights75.3%
5pm–8pm227 flights71.6%
8pm–5am—

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 89.9% of the time, against 71.6% for the evening window. That is 18 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 297 flights scheduled in it.

Across the year

Delta on SNA to SEA through the year

Darker means more delays. Figures are on-time percentages.November best, June worst

June is the worst month at 64.3% on time, 28 points below November, the best at 92.0%. 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. October was the busiest month here, with 92 flights.

Across the week, Saturday is the strongest day at 88.9% on time and Sunday the weakest at 75.9%. 13 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. Late-arriving aircraft accounts for 44% of the 13,000 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.

Late-arriving aircraft
44%
Carrier
44%
National Airspace System
12%
Extreme weather
0%

44% 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 13,000 reported delay minutes here, that single category outweighs weather by 44 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 12,841 reported delay minutes.

The largest share of delay minutes, 44%, 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 5,596 of the 13,000 delay minutes reported here.

Cancellations sit at 1.26% against a national 1.81%, which is ordinary. Diversions add another 0.21%.

Connections and stage length

What a delay here costs

6.3% 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.

The 978 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 runs 83.0% on time across 954 flights, within 2 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

One caution: this is a thin sample. 954 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 Delta on SNA to SEA

Put together: treat all of this as provisional. 954 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 81.2% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 940 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures