Flight number record
DL 2721
Delta Air Lines · San Francisco to Seattle
- Route
- SFO → SEA
- Departs
- 05:55
- Flights
- 349
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 2721, check with Delta Air Lines.
DL 2721 earns an A. Nearly every flight arrives inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 18 points better than the national rate of 77.3%. When something does go wrong the average delay runs close to two hours. That rests on 349 flights, with a median arrival 20 minutes early.
Set against the rest of the country, DL 2721's record is 18 points better than the US average of 77.3%. That gap is worth roughly 180 fewer late arrivals for every thousand flights.
Key figures
On time
95.3%
Arrivals under 15 minutes late, of 344 completed flights
Avg delay
116 min
Across delayed arrivals only, not all flights
Cancelled
1.43%
National rate is 1.89%
1 hour+ late
2.3%
National rate is 8.3%
These figures cover 349 flights between September 2025 and August 2026. The median arrival is 20 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 2721 flies
DL 2721 flies SFO to SEA without a single fixed slot. Its most common scheduled departure was 05:55, used on 146 of 349 flights, with 06:00 (134 flights) next.
- Departs 05:55146 flights41.8%
- Departs 06:00134 flights38.4%
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 05:55 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and DL 2721 runs 6 points better at 95.3%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
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Against the route
DL 2721 next to SFO to SEA
Every carrier on SFO to SEA combined arrived on time 72.3% of the time across 6,821 flights, so DL 2721 is 23 points ahead of it. Delta flew 986 flights on the same city pair under all its flight numbers, including this one, and those ran 79.5% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight beats by 14 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 2721thin sample | 349 | 95.3% | 116 min | 1.43% | A |
| All Delta Air Lines on SFO–SEA | 986 | 79.5% | 70 min | 1.83% | B |
| All carriers on SFO–SEA | 6,821 | 72.3% | 56 min | 1.08% | C |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 2721 quarter by quarter
Quarter by quarter DL 2721 held fairly steady: 100.0% in Jul–Sep 2025, 95.0% in Oct–Dec 2025, 95.2% in Jan–Mar 2026, 96.7% in Apr–Jun 2026 and 91.7% in Jul–Sep 2026. A spread of 8 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.
- Jul–Sep 202530 flights100.0%
- Oct–Dec 202580 flights95.0%
- Jan–Mar 202686 flights95.2%
- Apr–Jun 202691 flights96.7%
- Jul–Sep 202662 flights91.7%
Scale runs 85% to 100%.
By weekday, DL 2721 ranged from 90.0% on Tuesday to 100.0% on Friday. With about 50 flights behind each day, a spread of 10 points is inside normal variation, so the day you fly is not worth changing for this flight.
Arrival by arrival
How late DL 2721 runs when it is late
DL 2721 often beats the schedule: 234 of 344 completed flights, 68%, arrived 15 minutes or more early. The 16 late arrivals split 7 under half an hour, 1 between 30 and 60 minutes, and 8 an hour or more.
- 15+ min early234 flights68.0%
- Within 15 min94 flights27.3%
- 15–29 min late7 flights2.0%
- 30–59 min late1 flights0.3%
- 1–2 hours late3 flights0.9%
- 2+ hours late5 flights1.5%
Scale runs 0% to 100%.
Share of 344 completed flights by arrival against schedule.
Only 19 of 344 completed flights left 15 minutes late or more, too few to say how often the time is made up.
The worst days
Worst days for DL 2721
The latest arrival of the period was on 27 July 2026, 9 hours 41 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 27 July 2026 | 9 hours 41 minutes | Carrier |
| 23 July 2026 | 5 hours 46 minutes | Late-arriving aircraft |
| 24 January 2026 | 3 hours 41 minutes | Late-arriving aircraft |
| 21 April 2026 | 3 hours 19 minutes | Carrier |
| 12 February 2026 | 2 hours | Carrier |
Delay causes
Why DL 2721 runs late
Carrier accounts for 66% of the 1,849 delay minutes carriers reported here, and the remaining four split what is left.
- 66%Carrier
- 30%Late-arriving aircraft
- 4%National Airspace System
The largest share of delay minutes, 66%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,228 of the 1,849 delay minutes reported here. The split is drawn from 1,849 delay minutes reported on DL 2721.
Cancellations sit at 1.43% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
Badly late arrivals are rare here: only 2.3% 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.
The 679 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.
The same number turns up on one other city pair in the data, including BNA to DTW (9), but none flew often enough under DL 2721 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to SFO to SEA only.
One caution: this is a thin sample. 349 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 2721
For a booking, DL 2721 has one of the better records a US domestic flight can show: 95.3% on time and 1.43% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- SFO to SEA, every carrier and departure
- SEA to SFO, the return direction
- Delta Air Lines 1412 on the same route74.1%
- SkyWest Airlines 3707 on the same route65.1%
- Alaska Airlines 758 on the same route67.2%
- SkyWest Airlines 3991 on the same route64.3%
- United Airlines 2279 on the same route75.7%
- Alaska Airlines 1327 on the same route67.9%
- San Francisco International (SFO) 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
- Worst months to fly in the US, ranked by the data
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.