Route reliability record
SEA→ATL
Seattle to Atlanta
- Flights
- 3,294
- Period
- September 2025 to August 2026
- Distance
- 2,182 mi
- Carriers
- 2
This route earns a B+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 points better than the national rate of 77.3%. When something does go wrong the average delay runs a little over an hour. That rests on 3,294 SEA to ATL flights, of which Delta Air Lines flew 2,402 at 84.2% on time.
Best time to fly SEA to ATL: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 88.8% of the time and Wednesday flights 90.7%, against 84.0% for the route overall.
Set against the rest of the country, this route's record is 7 points better than the US average of 77.3%. That gap is worth roughly 67 fewer late arrivals for every thousand flights.
Key figures
On time
84.0%
Arrivals under 15 minutes late, of 3,255 completed flights
Avg delay
74 min
Across delayed arrivals only, not all flights
Cancelled
0.70%
National rate is 1.89%
Best carrier
Delta
84.2% on time across 2,402 flights
These figures cover 3,294 flights between September 2025 and August 2026. The median arrival is 9 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.
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Carrier by carrier
Which airline is most reliable on SEA to ATL
The two carriers here are closely matched: about a point 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 |
|---|---|---|---|---|---|
| Delta Air Lines | 2,402 | 84.2% | 84 min | 0.75% | B+ |
| Alaska Airlines | 892 | 83.2% | 49 min | 0.56% | B+ |
No carrier stands out. Delta tops the table at 84.2%, about a point clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Flights on SEA to ATL
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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Best ways to make this trip
The most reliable ways to fly Seattle to Atlanta
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. SEA → ATLSeattle to Atlanta | Delta Air Lines | 83.6% | 84.2% | 0.75% | 5am–8am, Wed | DL 569 06:00 |
| 2. SEA → ATLSeattle to Atlanta | Alaska Airlines | 82.7% | 83.2% | 0.56% | 8pm–5am, Wed | AS 334 09:05 |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 11 points, against about a point between the best and worst carrier.
- 5am–8am647 flights88.8%
- 8am–11am554 flights80.3%
- 11am–2pm571 flights78.3%
- 2pm–5pm616 flights82.7%
- 5pm–8pm31 flights83.9%
- 8pm–5am875 flights87.3%
Scale runs 70% to 95%.
The weak window here is the middle of the day, not the evening: 11am–2pm runs 78.3% on time against 88.8% for 5am–8am. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 8pm–5am window is the busiest, with 875 flights scheduled in it.
Explore
Filter SEA to ATL by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On SEA to ATL, the best departure window is 5am–8am at 88.8% on time and the worst is 11am–2pm at 78.3%, a wide gap of 10.5 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am88.8%
- 8–11am80.3%
- 11am–2pm78.3%
- 2–5pm82.7%
- 5–8pm83.9%
- 8pm–5am87.3%
best all US flightsScale 60% to 95%.
Across the year
When delays peak on this route
This route's year swings by 15 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
July is the worst month at 76.0% on time, 15 points below February, the best at 91.1%. 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 348 flights.
Across the week, Wednesday is the strongest day at 90.7% on time and Sunday the weakest at 79.5%, a spread of 11 points.
Delay causes
Why this route gets delayed
Carrier accounts for 59% of the 39,000 delay minutes carriers reported here, and the remaining four split what is left.
- 59%Carrier
- 21%Late-arriving aircraft
- 16%National Airspace System
- 4%Extreme weather
The largest share of delay minutes, 59%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 23,000 of the 39,000 delay minutes reported here. The split is drawn from 38,539 reported delay minutes.
Cancellations are rare at 0.70%, below the national 1.89% 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 actually costs
Badly late arrivals are rare here: only 4.6% land an hour or more behind schedule, against 8.3% 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 76.7% on time across 3,297 flights, 7 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 7 points of difference.
The sample behind these figures is 3,294 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.
Work out the risk of missing a connection in ATL after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 91.1% on time and July 76.0%, a swing of 15 points. If the dates move at all, move them out of July before you think about anything else. 3,255 completed flights over 12 months sit behind that.
Common questions
SEA to ATL questions
How often is SEA to ATL delayed?
About one flight in six arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 16.0% of the 3,294 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on SEA to ATL?
Delta Air Lines leads at 84.2% on time across 2,402 flights. Alaska Airlines is at the other end on 83.2%, a gap of about a point. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on SEA to ATL?
The 5am–8am departure window is the strongest at 88.8% on time. The 11am–2pm window is the weakest at 78.3%, 11 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are July delays on SEA to ATL?
July is the weakest month at 76.0% on time, compared with 91.1% in February. Across the year that is 15 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- ATL to SEA — the return legseparate record
- Seattle-Tacoma International (SEA) delay statistics
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Delta Air Lines on SEA to ATL84.2%
- Alaska Airlines on SEA to ATL83.2%
- SEA to LAX, a related route82.0%
- LGA to ATL, a related route75.5%
- SEA to PHX, a related route78.2%
- Delta Air Lines on-time record84.2%
- Alaska Airlines on-time record83.2%
- The best time of day to fly, according to 7.05 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. SEA to ATL and ATL to SEA are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.