Carrier route record
DLATL→SEA
Delta Air Lines · Atlanta to Seattle
- 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 ATL to SEA lands a B+, 2 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 roughly 55 minutes on average. That is a workable record, not a spotless one. That rests on 2,371 flights, with a median arrival 4 minutes early.
The US average over the same twelve months is 77.6%, so there is little to separate Delta on ATL to SEA from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
79.1%
Arrivals under 15 minutes late, of 2,352 completed flights
Avg delay
53 min
Across delayed arrivals only, not all flights
Cancelled
0.46%
National rate is 1.81%
Whole route
77.8%
Every carrier on ATL to SEA, 3,277 flights
These figures cover 2,371 flights between July 2025 and June 2026. The median arrival is 4 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 ATL to SEA
Delta flew 2,371 of the 3,277 flights on ATL to SEA, most of the route. Its 79.1% on time is about level with the route as a whole at 77.8%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from Delta at 79.1% to Alaska at 74.3%.
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.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines (this page) | 2,371 | 79.1% | 53 min | 0.46% | B+ |
| Alaska Airlines | 906 | 74.3% | 55 min | 1.10% | C |
Flight by flight
Delta flight numbers on ATL to SEA
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–8am323 flights79.7%
- 8am–11am407 flights84.9%
- 11am–2pm534 flights83.1%
- 2pm–5pm452 flights77.8%
- 5pm–8pm287 flights68.8%
- 8pm–5am368 flights76.2%
Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 84.9% of the time, against 68.8% 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 11am–2pm window is the busiest, with 534 flights scheduled in it.
Across the year
Delta on ATL to SEA through the year
December is the weak month at 63.7% on time, against 89.1% in September. 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. July was the busiest month here, with 255 flights.
Across the week, Saturday is the strongest day at 81.9% on time and Wednesday the weakest at 77.4%. 5 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 60% of the 26,000 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.
- 60%Carrier
- 25%National Airspace System
- 11%Late-arriving aircraft
- 5%Extreme weather
The largest share of delay minutes, 60%, 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 16,000 of the 26,000 delay minutes reported here. The split is drawn from 26,054 reported delay minutes.
Cancellations are rare at 0.46%, 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
Badly late arrivals are rare here: only 4.7% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
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 83.8% on time across 2,371 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 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 ATL to SEA
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 89.1% on time and December 63.7%, a swing of 25 points. If the dates move at all, move them out of December before you think about anything else. 2,352 completed flights over 12 months sit behind that.
Related
Where to go next
- ATL to SEA, every carrier
- Delta on SEA to ATL, the return leg
- Alaska Airlines on ATL to SEA74.3%
- Delta Air Lines network-wide record
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Seattle-Tacoma International (SEA) 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.