Flight number record
DL 1091
Delta Air Lines · Salt Lake City to San Francisco
- Route
- SLC → SFO
- Departs
- 22:45
- Flights
- 330
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 1091, check with Delta Air Lines.
DL 1091 draws a C+. About one flight in three arrives at least 15 minutes late, and the typical late arrival is about 55 minutes behind schedule. Build slack into anything you connect to. That rests on 330 flights, with a median arrival 3 minutes late.
The national on-time rate over the same period is 77.3%, so DL 1091 runs 12 points behind the country as a whole. Across a thousand flights that is about 120 extra late arrivals.
Key figures
On time
65.3%
Arrivals under 15 minutes late, of 329 completed flights
Avg delay
54 min
Across delayed arrivals only, not all flights
Cancelled
0.30%
National rate is 1.89%
1 hour+ late
7.0%
National rate is 8.3%
These figures cover 330 flights between September 2025 and August 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.
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Schedule
When DL 1091 flies
DL 1091 flies SLC to SFO without a single fixed slot. Its most common scheduled departure was 22:45, used on 91 of 330 flights, with 22:55 (77 flights) and 22:50 (42 flights) next.
- Departs 22:4591 flights27.6%
- Departs 22:5577 flights23.3%
- Departs 22:5042 flights12.7%
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 22:45 departure sits in the 8pm–5am window. Across every US flight scheduled in that window the on-time rate is 70.1%, and DL 1091 runs 5 points worse at 65.3%. 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 1091 next to SLC to SFO
Every carrier on SLC to SFO combined arrived on time 63.4% of the time across 3,433 flights, so DL 1091 is 2 points ahead of it. Delta flew 1,712 flights on the same city pair under all its flight numbers, including this one, and those ran 61.6% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight trails by 16 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 1091thin sample | 330 | 65.3% | 54 min | 0.30% | C+ |
| All Delta Air Lines on SLC–SFO | 1,712 | 61.6% | 52 min | 0.93% | D+ |
| All carriers on SLC–SFO | 3,433 | 63.4% | 63 min | 0.99% | D+ |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 1091 quarter by quarter
DL 1091 did not run the same all year. Its best quarter was Oct–Dec 2025 at 81.9% on time and its weakest Jul–Sep 2026 at 45.6%, a swing of 36 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 flights80.0%
- Oct–Dec 202572 flights81.9%
- Jan–Mar 202680 flights75.9%
- Apr–Jun 202691 flights50.5%
- Jul–Sep 202657 flights45.6%
Scale runs 35% to 85%.
By weekday, DL 1091 did best on Tuesday at 78.3% on time and worst on Sunday at 49.0%. Each day rests on about 47 flights, so a gap of 29 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late DL 1091 runs when it is late
The 114 late arrivals split 49 under half an hour, 42 between 30 and 60 minutes, and 23 an hour or more.
- 15+ min early56 flights17.0%
- Within 15 min159 flights48.3%
- 15–29 min late49 flights14.9%
- 30–59 min late42 flights12.8%
- 1–2 hours late16 flights4.9%
- 2+ hours late7 flights2.1%
Scale runs 0% to 100%.
Share of 329 completed flights by arrival against schedule.
Time lost at the gate mostly stays lost. Of 78 departures that left 15 minutes late or more, only 9 made it up before arrival. In the other direction, 45 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 SFO.
The worst days
Worst days for DL 1091
The latest arrival of the period was on 21 June 2026, 15 hours 34 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on four of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 21 June 2026 | 15 hours 34 minutes | Carrier |
| 22 December 2025 | 8 hours 21 minutes | Carrier |
| 24 July 2026 | 3 hours 24 minutes | Carrier |
| 28 July 2026 | 2 hours 23 minutes | Carrier |
| 17 April 2026 | 2 hours 19 minutes | Late-arriving aircraft |
Delay causes
Why DL 1091 runs late
Carrier accounts for 44% of the 6,199 delay minutes carriers reported here, and the remaining four split what is left.
- 44%Carrier
- 40%National Airspace System
- 14%Late-arriving aircraft
- 1%Extreme weather
The largest share of delay minutes, 44%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 2,757 of the 6,199 delay minutes reported here. The split is drawn from 6,199 delay minutes reported on DL 1091.
Cancellations are rare at 0.30%, 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
7.0% 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 55 minutes, which a normal layover absorbs.
The 599 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 330 flights under DL 1091 in the data flew SLC to SFO. 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. 330 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 1091
For a booking, read DL 1091 as 65.3% on time with 0.30% cancelled over 330 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- SLC to SFO, every carrier and departure
- SFO to SLC, the return direction
- Delta Air Lines 902 on the same route59.8%
- Delta Air Lines 1088 on the same route63.0%
- Delta Air Lines 920 on the same route63.9%
- Delta Air Lines 2762 on the same route53.2%
- Salt Lake City International (SLC) delay statistics
- San Francisco International (SFO) 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.