Flight number record

DL 1091

Delta Air Lines · Salt Lake City to San Francisco

Route: SLC → SFO
Departs: 22:45
Flights: 335
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 1091, check with Delta Air Lines.

DL 1091 sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 8 points worse than the national rate of 77.6%. The late ones land roughly 50 minutes behind schedule. That rests on 335 flights, with a median arrival 1 minute late.

The national on-time rate over the same period is 77.6%, so DL 1091 runs 8 points behind the country as a whole. Across a thousand flights that is about 78 extra late arrivals.

On time

69.8%

Arrivals under 15 minutes late, of 334 completed flights

Avg delay

52 min

Across delayed arrivals only, not all flights

Cancelled

0.30%

National rate is 1.81%

1 hour+ late

6.0%

National rate is 8.1%

These figures cover 335 flights between July 2025 and June 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.

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 103 of 335 flights, with 22:55 (52 flights) and 21:45 (48 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 22:45103 flights30.7%
Departs 22:5552 flights15.5%
Departs 21:4548 flights14.3%

Scale runs 0% to 100%. Rows with fewer than 30 flights show a dash.

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 70.5%, and DL 1091 runs level with that at 69.8%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.

Against the route

DL 1091 next to SLC to SFO

Every carrier on SLC to SFO combined arrived on time 69.0% of the time across 3,472 flights, so DL 1091 is about level with it. Delta flew 1,706 flights on the same city pair under all its flight numbers, including this one, and those ran 67.4% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight trails by 12 points.

DL 1091 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 1091thin sample	335	69.8%	52 min	0.30%	C+
All Delta Air Lines on SLC–SFO	1,706	67.4%	52 min	0.88%	C+
All carriers on SLC–SFO	3,472	69.0%	64 min	0.95%	C+
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	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 Apr–Jun 2026 at 50.5%, a swing of 31 points on roughly 84 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 202592 flights73.9%
Oct–Dec 202572 flights81.9%
Jan–Mar 202680 flights75.9%
Apr–Jun 202691 flights50.5%

Scale runs 40% to 85%. Rows with fewer than 30 flights show a dash.

By weekday, DL 1091 did best on Tuesday at 83.0% on time and worst on Sunday at 56.9%. Each day rests on about 48 flights, so a gap of 26 points is worth noticing but could still narrow in another year.

Delay causes

Why DL 1091 runs late

One category carries most of the weight here. Carrier accounts for 46% of the 5,291 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.

Carrier
46%
National Airspace System
43%
Late-arriving aircraft
10%
Extreme weather
1%

The largest share of delay minutes, 46%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 2,429 of the 5,291 delay minutes reported here. The split is drawn from 5,291 delay minutes reported on DL 1091.

Cancellations are rare at 0.30%, below the national 1.81% 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

6.0% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last roughly 50 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. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

Every one of the 335 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. 335 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 69.8% on time with 0.30% cancelled over 335 flights. Those are rates from the past twelve months, not a forecast for any particular day.

Where to go next

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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures