Flight profile · Delta Air Lines
DL1091
Salt Lake City (SLC) to San Francisco (SFO) · scheduled 10:59 PM – 11:59 PM
How DL1091 performs
750 operations, June 2024 – July 2026.
DL1091 arrived on time 74.2% of the time, against 71.5% for all SLC → SFO flights, so this departure is 2.7 percentage points better than the route as a whole. Against Delta Air Lines’ own flights on this route it is 4.2 points better.
Source: US DOT Bureau of Transportation Statistics · 750 operations, June 2024 – July 2026 · If DL1091 is cancelled or significantly changed, DOT’s automatic refund rule may entitle you to your money back. The refund checker walks through eligibility.
Where DL1091 is right now
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Against the rest of the route
| Flight or route | On time | Cancelled | Median delay | Severe | Flights |
|---|---|---|---|---|---|
| DL1091 | 74.2% | 0.40% | -2 min | 6.6% | 750 |
| Delta Air Lines on SLC → SFO | 70.0% | 0.60% | 0 min | 8.9% | 5,196 |
| All SLC → SFO flights | 71.5% | 0.71% | -3 min | 9.6% | 10,852 |
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026
Why DL1091 runs late
Where US DOT attributed the delay minutes on this flight.
crew, maintenance, boarding and fueling, all within the carrier’s control
airspace and airport capacity, including weather-driven flow control
the inbound aircraft was late, so this flight started late
weather severe enough to stop this flight specifically
Share of the delay minutes US DOT attributed to each cause for DL1091 on SLC → SFO. Only delays of 15 minutes or more are attributed.
Source: US DOT Bureau of Transportation Statistics · Data covering June 2024 – July 2026
Does a late aircraft delay this flight?
How often the plane that flies DL1091 comes in late, and what that does to the departure.
When the aircraft came in 15 or more minutes late, DL1091 pushed back an average of 30 minutes late; when it came in on time or early, an average of 4 minutes late.
Each departure is matched to the flight the same aircraft flew into SLC just before it, using the tail number in the DOT file, 660 of 747 departures in all. A departure is left out when that flight is unknown, was cancelled or diverted, or the aircraft had sat for more than 12 hours. A flight the airline cancelled never left and is not in the count, and one flown by a substitute aircraft is matched to the aircraft that flew it, not to the one first planned.
Against the network at the same turn length
| Share of departures | Inbound landed 15+ late | Left 15+ late after a late inbound | Left 15+ late after an on-time inbound |
|---|---|---|---|
| DL1091 | 18% | 46% | 15% |
| Network, same turn | 17% | 68% | 9% |
The schedule leaves a normal turn: enough time to clean and board if the aircraft is on time, little to spare if it is not.
The network row is every flight with a scheduled turn of 60 to 89 minutes. How often DL1091’s aircraft landed 15 or more minutes late is about the same as the network’s and, once the aircraft was late, how often DL1091 left 15 or more minutes late is lower than the network’s.
More: Which Flight Numbers Pay for a Late Aircraft lists the flight numbers that pass a late aircraft on.
Source: US DOT Bureau of Transportation Statistics · Data covering June 2024 – July 2026
From pushback to gate
When it leaves SLC late, does that still matter by the time it reaches SFO?
On arrival at SFO, DL1091 spends 9.7 min taxiing from touchdown to the gate — ground time a connecting passenger sits through before they can even leave the aircraft, on top of however late the flight itself ran. That is 1.8 minutes longer than a typical SFO arrival (7.9 min).
Departure delay is averaged over every pushback and arrival delay over every completed arrival, so the two counts differ by the flights that never reached SFO. Taxi-out is gate to wheels up and sits inside the scheduled block rather than on top of it; the comparison is 16,358 departures from SLC scheduled in the clock hour DL1091 most often leaves in. Taxi-in is landing to gate, compared against every arrival FlyerIntel has on file at SFO (436,060 flights), not just DL1091’s own. More on taxi time.
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026
The hour it leaves SLC
Part of any flight’s record belongs to the clock rather than to the flight. DL1091 has one departure time, so this is what that time is worth.
On-time arrival rate. 16,358 departures from SLC are scheduled in the 10 PM–11 PM hour over the period, against 355,300 across the whole day.
DL1091 is scheduled out of SLC at 10:59 PM, in the 10 PM–11 PM bank. Departures from SLC in that hour arrive on time 83.1% of the time against 84.0% across the airport’s whole day, so the hour DL1091 leaves in is an ordinary one for SLC and explains nothing about its record either way.
The two airport figures cover every departure from SLC to every destination, so they describe the slot rather than this journey — the like-for-like comparison against the route is above. Hours are scheduled local, and a number whose schedule moved between banks inside the period has no single hour and is not described here at all. Why the hour matters.
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026 · Hours below 120 departures are not scored.
Other routes DL1091 has flown
A flight number is a slot in a schedule, and carriers reassign it. These are the other city pairs this number served in the analysis period.
| Route | Operated | Flights | On time |
|---|---|---|---|
| MEM→MSP Memphis to Minneapolis | July 1, 2023 – June 6, 2024 | 227 | 91.0% |
| DTW→IND Detroit to Indianapolis | April 9, 2024 – May 6, 2024 | 24 | — |
| IND→DTW Indianapolis to Detroit | April 9, 2024 – May 6, 2024 | 24 | — |
| STL→SLC St. Louis to Salt Lake City | January 14, 2024 – March 8, 2024 | 26 | — |
| BOS→MIA Boston to Miami | January 8, 2024 – February 14, 2024 | 17 | — |
| MSP→SFO Minneapolis to San Francisco | December 16, 2023 – January 7, 2024 | 23 | — |
| SFO→MSP San Francisco to Minneapolis | December 16, 2023 – January 7, 2024 | 19 | — |
| ATL→IAD Atlanta to Washington | November 23–24, 2023 | 2 | — |
Because the same number has served different journeys, the statistics above describe only the route DL1091 currently operates. Blending them would produce an average of two different flights.
When it goes wrong
The average describes a usual day. This is the day that ruins a connection.
41 min late
against a median of 2 min early
Percentiles over 750 operations; cancelled and diverted flights are counted separately.
Source: US DOT Bureau of Transportation Statistics · Data covering June 2024 – July 2026
Other flights on this route
Same airports, same journey, different odds of arriving on time.
| Flight | Airline | On time | Median arrival | Operations |
|---|---|---|---|---|
| OO5736 | SkyWest Airlines | 79.2% | 9 min early | 898 |
| DL1091 this flight | Delta Air Lines | 74.2% | 2 min early | 750 |
| DL1088 | Delta Air Lines | 71.8% | 1 min early | 783 |
| DL920 | Delta Air Lines | 69.7% | 2 min early | 781 |
| DL902 | Delta Air Lines | 68.9% | 1 min late | 782 |
Every departure listed carries at least 600 operations, so the comparison is between figures that mean something. DL1091 is placed in the same ordering rather than left out of it; the rows around it are the most punctual departures on the route, not all of them, so this is a comparison and not a rank. Schedules change; confirm the departure still operates before booking around this.
Data and methodology
Calculated by FlyerIntel from 750 records of DL1091 operating SLC → SFO, published by the US DOT Bureau of Transportation Statistics. A flight counts as delayed when it arrives 15 or more minutes after schedule. Cancelled and diverted flights are excluded from the on-time rate and reported separately. Flight numbers are resolved as carrier plus number plus route, because the same number serves different routes over time.
Full methodology · Data sources · Report a problem
Related research: Most and Least Reliable Flight Numbers · The Delay You Inherit · Making Up Time in the Air
Analysis last recomputed