Flight number record
DL 871
Delta Air Lines · Salt Lake City to Seattle
- Route
- SLC → SEA
- Departs
- 17:10
- Flights
- 332
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 871, check with Delta Air Lines.
DL 871 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 about 50 minutes on average. That rests on 332 flights, with a median arrival 7 minutes early.
Key figures
On time
80.3%
Arrivals under 15 minutes late, of 330 completed flights
Avg delay
49 min
Across delayed arrivals only, not all flights
Cancelled
0.60%
National rate is 1.89%
1 hour+ late
4.2%
National rate is 8.3%
These figures cover 332 flights between September 2025 and August 2026. The median arrival is 7 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 871 flies
DL 871 flies SLC to SEA without a single fixed slot. Its most common scheduled departure was 17:10, used on 168 of 332 flights, with 17:20 (67 flights) and 17:31 (60 flights) next.
- Departs 17:10168 flights50.6%
- Departs 17:2067 flights20.2%
- Departs 17:3160 flights18.1%
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 17:10 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.0%, and DL 871 runs 12 points better at 80.3%. 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 871 next to SLC to SEA
Every carrier on SLC to SEA combined arrived on time 79.9% of the time across 4,098 flights, so DL 871 is about level with it. Delta flew 2,234 flights on the same city pair under all its flight numbers, including this one, and those ran 82.7% 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 871thin sample | 332 | 80.3% | 49 min | 0.60% | B+ |
| All Delta Air Lines on SLC–SEA | 2,234 | 82.7% | 53 min | 0.49% | B+ |
| All carriers on SLC–SEA | 4,098 | 79.9% | 55 min | 0.81% | B+ |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 871 quarter by quarter
DL 871 did not run the same all year. Its best quarter was Jul–Sep 2025 at 90.0% on time and its weakest Jul–Sep 2026 at 72.6%, a swing of 17 points on roughly 66 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 202576 flights77.3%
- Jan–Mar 202675 flights86.5%
- Apr–Jun 202689 flights79.8%
- Jul–Sep 202662 flights72.6%
Scale runs 65% to 95%.
By weekday, DL 871 did best on Tuesday at 87.2% on time and worst on Friday at 74.0%. Each day rests on about 47 flights, so a gap of 13 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late DL 871 runs when it is late
DL 871 often beats the schedule: 104 of 330 completed flights, 32%, arrived 15 minutes or more early. The 65 late arrivals split 26 under half an hour, 25 between 30 and 60 minutes, and 14 an hour or more.
- 15+ min early104 flights31.5%
- Within 15 min161 flights48.8%
- 15–29 min late26 flights7.9%
- 30–59 min late25 flights7.6%
- 1–2 hours late8 flights2.4%
- 2+ hours late6 flights1.8%
Scale runs 0% to 100%.
Share of 330 completed flights by arrival against schedule.
17 of 72 late departures made up the time and arrived on time, 24% of them. 10 flights left on time and still arrived late.
The worst days
Worst days for DL 871
The latest arrival of the period was on 30 November 2025, 3 hours 53 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 |
|---|---|---|
| 30 November 2025 | 3 hours 53 minutes | Carrier |
| 5 July 2026 | 3 hours 21 minutes | Carrier |
| 27 June 2026 | 3 hours 5 minutes | Extreme weather |
| 12 April 2026 | 3 hours 1 minute | Late-arriving aircraft |
| 27 December 2025 | 2 hours 15 minutes | Carrier |
Delay causes
Why DL 871 runs late
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 3,203 reported delay minutes.
- 41%Carrier
- 37%Late-arriving aircraft
- 13%National Airspace System
- 8%Extreme weather
37% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 3,203 reported delay minutes here, that single category outweighs weather by 4 to one. The split is drawn from 3,203 delay minutes reported on DL 871.
Cancellations are rare at 0.60%, 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 4.2% 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 689 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 332 flights under DL 871 in the data flew SLC 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. 332 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 871
For a booking, read DL 871 as 80.3% on time with 0.60% cancelled over 332 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- SLC to SEA, every carrier and departure
- SEA to SLC, the return direction
- Delta Air Lines 2874 on the same route92.6%
- Delta Air Lines 2995 on the same route87.1%
- Delta Air Lines 2817 on the same route77.3%
- Alaska Airlines 796 on the same route83.9%
- Delta Air Lines 2921 on the same route84.0%
- Alaska Airlines 734 on the same route65.9%
- Salt Lake City International (SLC) 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
- Why the first flight of the morning is statistically safest
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.