Flight number record
UA 2391
United Airlines · Denver to San Francisco
- Route
- DEN → SFO
- Departs
- 07:45
- Flights
- 341
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 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, 6 points worse than the national rate of 77.3%. The late ones land roughly 50 minutes behind schedule. That rests on 341 flights, with a median arrival 2 minutes late.
The national on-time rate over the same period is 77.3%, so UA 2391 runs 6 points behind the country as a whole. Across a thousand flights that is about 56 extra late arrivals.
Key figures
On time
71.7%
Arrivals under 15 minutes late, of 339 completed flights
Avg delay
48 min
Across delayed arrivals only, not all flights
Cancelled
0.59%
National rate is 1.89%
1 hour+ late
5.0%
National rate is 8.3%
These figures cover 341 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 UA 2391 flies
UA 2391 flies DEN to SFO without a single fixed slot. Its most common scheduled departure was 07:45, used on 124 of 341 flights, with 07:40 (82 flights) and 07:47 (56 flights) next.
- Departs 07:45124 flights36.4%
- Departs 07:4082 flights24.0%
- Departs 07:4756 flights16.4%
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 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 18 points worse at 71.7%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
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Against the route
UA 2391 next to DEN to SFO
Every carrier on DEN to SFO combined arrived on time 63.2% of the time across 5,488 flights, so UA 2391 is 9 points ahead of it. United flew 3,429 flights on the same city pair under all its flight numbers, including this one, and those ran 69.0% on time. Across its whole network United Airlines managed 78.8%, which this flight trails by 7 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 2391thin sample | 341 | 71.7% | 48 min | 0.59% | C+ |
| All United Airlines on DEN–SFO | 3,429 | 69.0% | 63 min | 0.23% | C+ |
| All carriers on DEN–SFO | 5,488 | 63.2% | 62 min | 0.40% | D+ |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | 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 85 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%
- Jul–Sep 202662 flights75.8%
Scale runs 50% to 90%. Rows with fewer than 30 flights show a dash.
By weekday, UA 2391 did best on Wednesday at 78.7% on time and worst on Thursday at 63.3%. Each day rests on about 49 flights, so a gap of 15 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late UA 2391 runs when it is late
The 96 late arrivals split 40 under half an hour, 39 between 30 and 60 minutes, and 17 an hour or more.
- 15+ min early72 flights21.2%
- Within 15 min171 flights50.4%
- 15–29 min late40 flights11.8%
- 30–59 min late39 flights11.5%
- 1–2 hours late9 flights2.7%
- 2+ hours late8 flights2.4%
Scale runs 0% to 100%.
Share of 339 completed flights by arrival against schedule.
6 of 44 late departures made up the time and arrived on time, 14% of them. In the other direction, 58 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 UA 2391
The latest arrival of the period was on 19 June 2026, 5 hours 38 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 19 June 2026 | 5 hours 38 minutes | Late-arriving aircraft |
| 14 June 2026 | 3 hours 26 minutes | Carrier |
| 16 January 2026 | 3 hours 23 minutes | Carrier |
| 27 January 2026 | 2 hours 57 minutes | Late-arriving aircraft |
| 1 December 2025 | 2 hours 51 minutes | Late-arriving aircraft |
Delay causes
Why UA 2391 runs late
National Airspace System accounts for 54% of the 4,558 delay minutes carriers reported here, and the remaining four split what is left.
- 54%National Airspace System
- 28%Late-arriving aircraft
- 18%Carrier
54% 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 2,469 minutes out of 4,558, against a national NAS share of 21%. The split is drawn from 4,558 delay minutes reported on UA 2391.
Cancellations are rare at 0.59%, 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
5.0% 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 roughly 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.
The same number turns up on two other city pairs in the data, including SFO to SAN (125) and MCI to DEN (24), 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. 341 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 71.7% on time with 0.59% cancelled over 341 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 1812 on the same route73.4%
- United Airlines 2633 on the same route68.7%
- United Airlines 2367 on the same route95.3%
- United Airlines 1007 on the same route66.2%
- United Airlines 1561 on the same route66.8%
- United Airlines 2123 on the same route56.6%
- 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.