Flight number record
UA 2633
United Airlines · Denver to San Francisco
- Route
- DEN → SFO
- Departs
- 15:55
- Flights
- 364
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s UA 2633, check with United Airlines.
UA 2633 sits in the middle of the pack with a B+. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 364 flights, with a median arrival 3 minutes early.
Key figures
On time
75.4%
Arrivals under 15 minutes late, of 362 completed flights
Avg delay
77 min
Across delayed arrivals only, not all flights
Cancelled
0.55%
National rate is 1.81%
1 hour+ late
10.5%
National rate is 8.1%
These figures cover 364 flights between July 2025 and June 2026. Beyond the headline rate, 10.5% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Schedule
When UA 2633 flies
UA 2633 flies DEN to SFO without a single fixed slot. Its most common scheduled departure was 15:55, used on 84 of 364 flights, with 15:59 (52 flights) and 15:47 (41 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 15:5584 flights23.1%
- Departs 15:5952 flights14.3%
- Departs 15:4741 flights11.3%
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 15:55 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 72.4%, and UA 2633 runs 3 points better at 75.4%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.
Against the route
UA 2633 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 2633 is 10 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 4 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 2633thin sample | 364 | 75.4% | 77 min | 0.55% | B+ |
| 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 2633 quarter by quarter
UA 2633 did not run the same all year. Its best quarter was Jan–Mar 2026 at 82.2% on time and its weakest Apr–Jun 2026 at 60.4%, a swing of 22 points on roughly 91 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 202592 flights80.0%
- Oct–Dec 202591 flights79.1%
- Jan–Mar 202690 flights82.2%
- Apr–Jun 202691 flights60.4%
Scale runs 50% to 90%. Rows with fewer than 30 flights show a dash.
By weekday, UA 2633 ranged from 72.5% on Sunday to 80.8% on Wednesday. With about 52 flights behind each day, a spread of 8 points is inside normal variation, so the day you fly is not worth changing for this flight.
Delay causes
Why UA 2633 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 6,823 reported delay minutes.
- 41%National Airspace System
- 36%Late-arriving aircraft
- 22%Carrier
- 2%Extreme weather
36% 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 6,823 reported delay minutes here, that single category outweighs weather by 21 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 6,823 delay minutes reported on UA 2633.
Cancellations are rare at 0.55%, 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
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.5% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
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 SFO to SAN (112), SAN to ORD (30) and CLE to DEN (26), but none flew often enough under UA 2633 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. 364 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 2633
For a booking, read UA 2633 as 75.4% on time with 0.55% cancelled over 364 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 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%
- United Airlines 2391 on the same route70.8%
- 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
- 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.