Flight number record
UA 2348
United Airlines · San Francisco to Denver
- Route
- SFO → DEN
- Departs
- 08:35
- Flights
- 310
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s UA 2348, check with United Airlines.
UA 2348 earns an A+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 9 points better than the national rate of 77.6%. When something does go wrong the average delay runs about an hour. That rests on 310 flights, with a median arrival 5 minutes early.
Set against the rest of the country, UA 2348's record is 9 points better than the US average of 77.6%. That gap is worth roughly 87 fewer late arrivals for every thousand flights.
Key figures
On time
86.3%
Arrivals under 15 minutes late, of 307 completed flights
Avg delay
65 min
Across delayed arrivals only, not all flights
Cancelled
0.97%
National rate is 1.81%
1 hour+ late
3.9%
National rate is 8.1%
These figures cover 310 flights between July 2025 and June 2026. The median arrival is 5 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
Schedule
When UA 2348 flies
UA 2348 flies SFO to DEN without a single fixed slot. Its most common scheduled departure was 08:35, used on 163 of 310 flights, with 08:30 (75 flights) and 08:31 (41 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 08:35163 flights52.6%
- Departs 08:3075 flights24.2%
- Departs 08:3141 flights13.2%
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 08:35 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 84.1%, and UA 2348 runs 2 points better at 86.3%. 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 2348 next to SFO to DEN
Every carrier on SFO to DEN combined arrived on time 75.5% of the time across 5,410 flights, so UA 2348 is 11 points ahead of it. United flew 3,370 flights on the same city pair under all its flight numbers, including this one, and those ran 82.2% on time. Across its whole network United Airlines managed 79.0%, which this flight beats by 7 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 2348thin sample | 310 | 86.3% | 65 min | 0.97% | A+ |
| All United Airlines on SFO–DEN | 3,370 | 82.2% | 59 min | 0.27% | B+ |
| All carriers on SFO–DEN | 5,410 | 75.5% | 59 min | 0.46% | B+ |
| United Airlines, whole network | 821,041 | 79.0% | 72 min | 1.01% | B |
Across the year
UA 2348 quarter by quarter
UA 2348 did not run the same all year. Its best quarter was Jul–Sep 2025 at 94.0% on time and its weakest Oct–Dec 2025 at 74.6%, a swing of 19 points on roughly 78 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 202586 flights94.0%
- Oct–Dec 202567 flights74.6%
- Jan–Mar 202666 flights93.8%
- Apr–Jun 202691 flights82.4%
Scale runs 65% to 100%. Rows with fewer than 30 flights show a dash.
By weekday, UA 2348 did best on Saturday at 95.3% on time and worst on Friday at 79.1%. Each day rests on about 44 flights, so a gap of 16 points is worth noticing but could still narrow in another year.
Delay causes
Why UA 2348 runs late
One category carries most of the weight here. Late-arriving aircraft accounts for 46% of the 2,744 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.
- 46%Late-arriving aircraft
- 27%Carrier
- 27%National Airspace System
46% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 2,744 reported delay minutes here, that single category outweighs weather by 46 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 2,744 delay minutes reported on UA 2348.
Cancellations sit at 0.97% against a national 1.81%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
Badly late arrivals are rare here: only 3.9% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
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 four other city pairs in the data, including DEN to SLC (114), DEN to RSW (32) and DEN to MIA (21), but none flew often enough under UA 2348 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to SFO to DEN only.
One caution: this is a thin sample. 310 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 2348
For a booking, UA 2348 has one of the better records a US domestic flight can show: 86.3% on time and 0.97% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- SFO to DEN, every carrier and departure
- DEN to SFO, the return direction
- Frontier Airlines 1230 on the same route87.1%
- San Francisco International (SFO) delay statistics
- Denver International (DEN) 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
- Why the first flight of the morning is statistically safest
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.