Flight number record
UA 2348
United Airlines · San Francisco to Denver
- Route
- SFO → DEN
- Departs
- 08:35
- Flights
- 289
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s UA 2348, check with United Airlines.
UA 2348 lands a B+, 5 points better than the national rate of 77.3%. About one flight in six arrives 15 minutes late or worse, and those flights are late by roughly 50 minutes on average. That rests on 289 flights, with a median arrival 3 minutes early.
Set against the rest of the country, UA 2348's record is 5 points better than the US average of 77.3%. That gap is worth roughly 46 fewer late arrivals for every thousand flights.
Key figures
On time
81.9%
Arrivals under 15 minutes late, of 288 completed flights
Avg delay
52 min
Across delayed arrivals only, not all flights
Cancelled
0.35%
National rate is 1.89%
1 hour+ late
4.2%
National rate is 8.3%
These figures cover 289 flights between September 2025 and August 2026. The median arrival is 3 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.
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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 101 of 289 flights, with 08:31 (82 flights) and 08:30 (75 flights) next.
- Departs 08:35101 flights34.9%
- Departs 08:3182 flights28.4%
- Departs 08:3075 flights26.0%
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 08:35 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 83.9%, and UA 2348 runs 2 points worse at 81.9%. 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 2348 next to SFO to DEN
Every carrier on SFO to DEN combined arrived on time 74.7% of the time across 5,486 flights, so UA 2348 is 7 points ahead of it. United flew 3,427 flights on the same city pair under all its flight numbers, including this one, and those ran 82.1% on time. Across its whole network United Airlines managed 78.8%, which this flight beats by 3 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 2348thin sample | 289 | 81.9% | 52 min | 0.35% | B+ |
| All United Airlines on SFO–DEN | 3,427 | 82.1% | 58 min | 0.18% | B+ |
| All carriers on SFO–DEN | 5,486 | 74.7% | 61 min | 0.46% | C+ |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | B |
Across the year
UA 2348 quarter by quarter
UA 2348 did not run the same all year. Its best quarter was Jan–Mar 2026 at 93.8% on time and its weakest Jul–Sep 2026 at 70.7%, a swing of 23 points on roughly 72 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 202524 flights—
- Oct–Dec 202567 flights74.6%
- Jan–Mar 202666 flights93.8%
- Apr–Jun 202691 flights82.4%
- Jul–Sep 202641 flights70.7%
Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.
By weekday, UA 2348 did best on Thursday at 87.5% on time and worst on Friday at 75.0%. Each day rests on about 41 flights, so a gap of 13 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late UA 2348 runs when it is late
Most of the lateness is short. 29 of the 52 late arrivals were under half an hour behind, and 12 reached an hour or more.
- 15+ min early49 flights17.0%
- Within 15 min187 flights64.9%
- 15–29 min late29 flights10.1%
- 30–59 min late11 flights3.8%
- 1–2 hours late4 flights1.4%
- 2+ hours late8 flights2.8%
Scale runs 0% to 100%.
Share of 288 completed flights by arrival against schedule.
9 of 47 late departures made up the time and arrived on time, 19% of them. 14 flights left on time and still arrived late.
The worst days
Worst days for UA 2348
The latest arrival of the period was on 17 February 2026, 3 hours 33 minutes behind schedule; most of its delay minutes were filed as national airspace system delay. The five worst days are spread across February, December, April, November and May, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 17 February 2026 | 3 hours 33 minutes | National Airspace System |
| 19 December 2025 | 3 hours 23 minutes | National Airspace System |
| 14 April 2026 | 2 hours 55 minutes | Carrier |
| 21 November 2025 | 2 hours 50 minutes | Late-arriving aircraft |
| 28 May 2026 | 2 hours 38 minutes | Late-arriving aircraft |
Delay causes
Why UA 2348 runs late
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 2,725 reported delay minutes.
- 41%Late-arriving aircraft
- 31%Carrier
- 28%National Airspace System
41% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 2,725 reported delay minutes here, that single category outweighs weather by 41 to one. The split is drawn from 2,725 delay minutes reported on UA 2348.
Cancellations are rare at 0.35%, 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
Badly late arrivals are rare here: only 4.2% land an hour or more behind schedule, against 8.3% 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.
The same number turns up on four other city pairs in the data, including DEN to SLC (129), DEN to RSW (61) 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. 289 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, read UA 2348 as 81.9% on time with 0.35% cancelled over 289 flights. Those are rates from the past twelve months, not a forecast for any particular 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 route89.1%
- United Airlines 1430 on the same route76.4%
- United Airlines 1596 on the same route67.7%
- 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.