Flight number record
UA 2391
United Airlines · Denver to San Francisco
- Route
- DEN → SFO
- Departs
- 07:45
- Flights
- 279
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s UA 2391, check with United Airlines.
UA 2391 sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 7 points worse than the national rate of 77.6%. The late ones land about 50 minutes behind schedule. That rests on 279 flights, with a median arrival 1 minute early.
The national on-time rate over the same period is 77.6%, so UA 2391 runs 7 points behind the country as a whole. Across a thousand flights that is about 68 extra late arrivals.
Key figures
On time
70.8%
Arrivals under 15 minutes late, of 277 completed flights
Avg delay
51 min
Across delayed arrivals only, not all flights
Cancelled
0.72%
National rate is 1.81%
1 hour+ late
5.8%
National rate is 8.1%
These figures cover 279 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 UA 2391 flies
UA 2391 flies DEN to SFO without a single fixed slot. Its most common scheduled departure was 07:45, used on 103 of 279 flights, with 07:47 (56 flights) and 07:40 (41 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 07:45103 flights36.9%
- Departs 07:4756 flights20.1%
- Departs 07:4041 flights14.7%
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 07:45 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and UA 2391 runs 19 points worse at 70.8%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
Against the route
UA 2391 next to DEN to SFO
Every carrier on DEN to SFO combined arrived on time 65.8% of the time across 5,415 flights, so UA 2391 is 5 points ahead of it. United flew 3,373 flights on the same city pair under all its flight numbers, including this one, and those ran 71.2% on time. Across its whole network United Airlines managed 79.0%, which this flight trails by 8 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 2391thin sample | 279 | 70.8% | 51 min | 0.72% | C+ |
| All United Airlines on DEN–SFO | 3,373 | 71.2% | 63 min | 0.42% | C+ |
| All carriers on DEN–SFO | 5,415 | 65.8% | 61 min | 0.48% | C+ |
| United Airlines, whole network | 821,041 | 79.0% | 72 min | 1.01% | B |
Across the year
UA 2391 quarter by quarter
UA 2391 did not run the same all year. Its best quarter was Jan–Mar 2026 at 83.3% on time and its weakest Apr–Jun 2026 at 58.9%, a swing of 24 points on roughly 93 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 20256 flights—
- Oct–Dec 202592 flights68.1%
- Jan–Mar 202690 flights83.3%
- Apr–Jun 202691 flights58.9%
Scale runs 50% to 90%. Rows with fewer than 30 flights show a dash.
By weekday, UA 2391 did best on Wednesday at 78.9% on time and worst on Thursday at 60.0%. Each day rests on about 40 flights, so a gap of 19 points is worth noticing but could still narrow in another year.
Delay causes
Why UA 2391 runs late
One category carries most of the weight here. National Airspace System accounts for 53% of the 4,122 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.
- 53%National Airspace System
- 31%Late-arriving aircraft
- 16%Carrier
53% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 2,184 minutes out of 4,122, against a national NAS share of 21%. The split is drawn from 4,122 delay minutes reported on UA 2391.
Cancellations are rare at 0.72%, 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
5.8% 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 about 50 minutes, which a normal layover absorbs.
The 967 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.
The same number turns up on two other city pairs in the data, including SFO to SAN (125) and MCI to DEN (86), but none flew often enough under UA 2391 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to DEN to SFO only.
One caution: this is a thin sample. 279 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 UA 2391
For a booking, read UA 2391 as 70.8% on time with 0.72% cancelled over 279 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- DEN to SFO, every carrier and departure
- SFO to DEN, the return direction
- United Airlines 2633 on the same route75.4%
- United Airlines 2367 on the same route95.3%
- United Airlines 1812 on the same route75.3%
- United Airlines 1007 on the same route67.6%
- United Airlines 1561 on the same route71.0%
- Frontier Airlines 3439 on the same route68.6%
- Denver International (DEN) delay statistics
- San Francisco International (SFO) delay statistics
- United Airlines on-time record
- Every United Airlines 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 United Airlines’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.