Flight number record
DL 629
Delta Air Lines · Atlanta to Seattle
- Route
- ATL → SEA
- Departs
- 11:30
- Flights
- 365
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 629, check with Delta Air Lines.
DL 629 lands a B+, 3 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by roughly 45 minutes on average. That rests on 365 flights, with a median arrival 4 minutes early.
Key figures
On time
80.4%
Arrivals under 15 minutes late, of 362 completed flights
Avg delay
47 min
Across delayed arrivals only, not all flights
Cancelled
0.55%
National rate is 1.89%
1 hour+ late
3.0%
National rate is 8.3%
These figures cover 365 flights between September 2025 and August 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.
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Schedule
When DL 629 flies
DL 629 flies ATL to SEA without a single fixed slot. Its most common scheduled departure was 11:30, used on 50 of 365 flights, with 12:00 (47 flights) and 11:45 (38 flights) next.
- Departs 11:3050 flights13.7%
- Departs 12:0047 flights12.9%
- Departs 11:4538 flights10.4%
Scale runs 0% to 100%.
Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.
A 11:30 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.3%, and DL 629 runs 2 points better at 80.4%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.
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Against the route
DL 629 next to ATL to SEA
Every carrier on ATL to SEA combined arrived on time 76.7% of the time across 3,297 flights, so DL 629 is 4 points ahead of it. Delta flew 2,404 flights on the same city pair under all its flight numbers, including this one, and those ran 76.8% on time. Across its whole network Delta Air Lines managed 81.1%, close to this flight's figure.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 629 | 365 | 80.4% | 47 min | 0.55% | B+ |
| All Delta Air Lines on ATL–SEA | 2,404 | 76.8% | 58 min | 0.62% | B+ |
| All carriers on ATL–SEA | 3,297 | 76.7% | 57 min | 0.73% | B+ |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 629 quarter by quarter
DL 629 did not run the same all year. Its best quarter was Jul–Sep 2025 at 90.0% on time and its weakest Jan–Mar 2026 at 72.7%, a swing of 17 points on roughly 73 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.
- Jul–Sep 202530 flights90.0%
- Oct–Dec 202592 flights76.1%
- Jan–Mar 202690 flights72.7%
- Apr–Jun 202691 flights84.6%
- Jul–Sep 202662 flights86.9%
Scale runs 65% to 95%.
By weekday, DL 629 did best on Sunday at 90.4% on time and worst on Wednesday at 75.0%. Each day rests on about 52 flights, so a gap of 15 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late DL 629 runs when it is late
The 71 late arrivals split 34 under half an hour, 26 between 30 and 60 minutes, and 11 an hour or more.
- 15+ min early77 flights21.3%
- Within 15 min214 flights59.1%
- 15–29 min late34 flights9.4%
- 30–59 min late26 flights7.2%
- 1–2 hours late3 flights0.8%
- 2+ hours late8 flights2.2%
Scale runs 0% to 100%.
Share of 362 completed flights by arrival against schedule.
15 of 60 late departures made up the time and arrived on time, 25% of them. In the other direction, 26 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at SEA.
The worst days
Worst days for DL 629
The latest arrival of the period was on 7 December 2025, 4 hours 9 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). Three of the five worst days fell in December 2025.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 7 December 2025 | 4 hours 9 minutes | Carrier |
| 8 January 2026 | 3 hours 39 minutes | Carrier |
| 18 December 2025 | 2 hours 46 minutes | Carrier |
| 6 December 2025 | 2 hours 37 minutes | Carrier |
| 9 January 2026 | 2 hours 22 minutes | Carrier |
Delay causes
Why DL 629 runs late
Carrier accounts for 59% of the 3,340 delay minutes carriers reported here, and the remaining four split what is left.
- 59%Carrier
- 25%National Airspace System
- 13%Late-arriving aircraft
- 2%Extreme weather
The largest share of delay minutes, 59%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,974 of the 3,340 delay minutes reported here. The split is drawn from 3,340 delay minutes reported on DL 629.
Cancellations are rare at 0.55%, 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 routes
What a delay on this flight costs
Badly late arrivals are rare here: only 3.0% 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.
Every one of the 365 flights under DL 629 in the data flew ATL to SEA. The number was not reused on any other city pair, which makes this a clean record of one route.
One caution: this is a thin sample. 365 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 DL 629
For a booking, read DL 629 as 80.4% on time with 0.55% cancelled over 365 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- ATL to SEA, every carrier and departure
- SEA to ATL, the return direction
- Delta Air Lines 774 on the same route84.6%
- Delta Air Lines 444 on the same route78.3%
- Delta Air Lines 481 on the same route78.4%
- Delta Air Lines 714 on the same route65.0%
- Alaska Airlines 377 on the same route85.3%
- Delta Air Lines 903 on the same route77.7%
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Seattle-Tacoma International (SEA) delay statistics
- Delta Air Lines on-time record
- Every Delta Air Lines flight number with a record
- The most and least reliable flight numbers in the US
- The best time of day to fly, according to 7.05 million flight records
A flight number here means Delta Air Lines’s own number as it reports to the DOT. How the figures are computed is on the methodology page.
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.