Carrier route record

DLSEA→ATL

Delta Air Lines · Seattle to Atlanta

Flights: 2,371
Period: July 2025 to June 2026
Share of route: 72%
Carriers: 2

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

Delta on SEA to ATL lands a B+, 6 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 an hour and a half on average. That is a workable record, not a spotless one. That rests on 2,371 flights, with a median arrival 8 minutes early.

Set against the rest of the country, Delta's SEA to ATL record is 6 points better than the US average of 77.6%. That gap is worth roughly 62 fewer late arrivals for every thousand flights.

On time

83.8%

Arrivals under 15 minutes late, of 2,351 completed flights

Avg delay

86 min

Across delayed arrivals only, not all flights

Cancelled

0.51%

National rate is 1.81%

Whole route

82.8%

Every carrier on SEA to ATL, 3,276 flights

These figures cover 2,371 flights between July 2025 and June 2026. The median arrival is 8 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 ATL

Delta flew 2,371 of the 3,276 flights on SEA to ATL, most of the route. Its 83.8% on time is about level with the route as a whole at 82.8%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from Delta at 83.8% to Alaska at 80.3%.

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.

On-time performance by carrier on SEA to ATL
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines (this page)	2,371	83.8%	86 min	0.51%	B+
Alaska Airlines	905	80.3%	46 min	0.66%	B+

Flight by flight

Delta flight numbers on SEA to ATL

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 13 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–8am647 flights89.9%
8am–11am127 flights84.1%
11am–2pm570 flights79.8%
2pm–5pm380 flights82.4%
5pm–8pm52 flights76.9%
8pm–5am595 flights82.2%

Scale runs 70% 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 76.9% for the evening window. That is 13 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 647 flights scheduled in it.

Across the year

Delta on SEA to ATL through the year

Darker means more delays. Figures are on-time percentages.September best, July worst

July is the worst month at 76.8% on time, 11 points below September, the best at 88.2%. 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. July was the busiest month here, with 255 flights.

Across the week, Wednesday is the strongest day at 88.4% on time and Sunday the weakest at 79.1%. 9 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 61% of the 33,000 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.

Carrier
61%
Late-arriving aircraft
19%
National Airspace System
14%
Extreme weather
6%

The largest share of delay minutes, 61%, 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 20,000 of the 33,000 delay minutes reported here. The split is drawn from 32,717 reported delay minutes.

Cancellations are rare at 0.51%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.

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 an hour and a half, which a normal layover absorbs.

At 2,182 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 79.1% on time across 2,371 flights, 5 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 5 points of difference.

The sample behind these figures is 2,371 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 ATL

Put together: avoid the 5pm–8pm departure. It runs 76.9% on time against 89.9% for the 5am–8am slot, and that 13 points is the largest single thing you control here. Alaska Airlines is the strongest operator if the fares are close. 2,351 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