Flight number record
DL 2851
Delta Air Lines · Seattle to Denver
- Route
- SEA → DEN
- Departs
- 19:40
- Flights
- 255
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 2851, check with Delta Air Lines.
DL 2851 lands a B, about a point worse than the national rate of 77.3%. About one flight in four arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 255 flights, with a median arrival 8 minutes early.
Key figures
On time
76.1%
Arrivals under 15 minutes late, of 251 completed flights
Avg delay
56 min
Across delayed arrivals only, not all flights
Cancelled
1.57%
National rate is 1.89%
1 hour+ late
7.6%
National rate is 8.3%
These figures cover 255 flights between September 2025 and August 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.
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Schedule
When DL 2851 flies
DL 2851 flies SEA to DEN without a single fixed slot. Its most common scheduled departure was 19:40, used on 62 of 255 flights, with 19:59 (58 flights) and 19:56 (30 flights) next.
- Departs 19:4062 flights24.3%
- Departs 19:5958 flights22.7%
- Departs 19:5630 flights11.8%
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 19:40 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.0%, and DL 2851 runs 8 points better at 76.1%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.
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Against the route
DL 2851 next to SEA to DEN
Every carrier on SEA to DEN combined arrived on time 78.3% of the time across 6,333 flights, so DL 2851 is 2 points behind it. Delta flew 869 flights on the same city pair under all its flight numbers, including this one, and those ran 72.9% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight trails by 5 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 2851thin sample | 255 | 76.1% | 56 min | 1.57% | B |
| All Delta Air Lines on SEA–DEN | 869 | 72.9% | 57 min | 0.92% | C+ |
| All carriers on SEA–DEN | 6,333 | 78.3% | 58 min | 0.68% | B+ |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 2851 quarter by quarter
Quarter by quarter DL 2851 held fairly steady: 79.8% in Jan–Mar 2026, 73.3% in Apr–Jun 2026 and 73.8% in Jul–Sep 2026. A spread of 7 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.
- Oct–Dec 202512 flights—
- Jan–Mar 202690 flights79.8%
- Apr–Jun 202691 flights73.3%
- Jul–Sep 202662 flights73.8%
Scale runs 65% to 85%. Rows with fewer than 30 flights show a dash.
By weekday, DL 2851 did best on Saturday at 86.5% on time and worst on Friday at 65.7%. Each day rests on about 36 flights, so a gap of 21 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late DL 2851 runs when it is late
DL 2851 often beats the schedule: 93 of 251 completed flights, 37%, arrived 15 minutes or more early. The 60 late arrivals split 21 under half an hour, 20 between 30 and 60 minutes, and 19 an hour or more.
- 15+ min early93 flights37.1%
- Within 15 min98 flights39.0%
- 15–29 min late21 flights8.4%
- 30–59 min late20 flights8.0%
- 1–2 hours late12 flights4.8%
- 2+ hours late7 flights2.8%
Scale runs 0% to 100%.
Share of 251 completed flights by arrival against schedule.
11 of 58 late departures made up the time and arrived on time, 19% of them. In the other direction, 13 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 DEN.
The worst days
Worst days for DL 2851
The latest arrival of the period was on 13 August 2026, 2 hours 55 minutes behind schedule; most of its delay minutes were filed as national airspace system delay. The five worst days are spread across August, July, January and June, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 13 August 2026 | 2 hours 55 minutes | National Airspace System |
| 31 July 2026 | 2 hours 23 minutes | Carrier |
| 12 July 2026 | 2 hours 12 minutes | Late-arriving aircraft |
| 26 January 2026 | 2 hours 11 minutes | Late-arriving aircraft |
| 18 June 2026 | 2 hours 4 minutes | Carrier |
Delay causes
Why DL 2851 runs late
Carrier accounts for 52% of the 3,351 delay minutes carriers reported here, and the remaining four split what is left.
- 52%Carrier
- 27%Late-arriving aircraft
- 19%National Airspace System
- 2%Extreme weather
The largest share of delay minutes, 52%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,745 of the 3,351 delay minutes reported here. The split is drawn from 3,351 delay minutes reported on DL 2851.
Cancellations sit at 1.57% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
7.6% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
The 1,024 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.
Every one of the 255 flights under DL 2851 in the data flew SEA to DEN. 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. 255 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 2851
For a booking, read DL 2851 as 76.1% on time with 1.57% cancelled over 255 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- SEA to DEN, every carrier and departure
- DEN to SEA, the return direction
- United Airlines 757 on the same route85.4%
- United Airlines 1505 on the same route91.1%
- Alaska Airlines 602 on the same route74.7%
- Frontier Airlines 3406 on the same route75.0%
- Alaska Airlines 682 on the same route86.1%
- Seattle-Tacoma International (SEA) delay statistics
- Denver International (DEN) 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.