Flight number record
UA 1561
United Airlines · Denver to San Francisco
- Route
- DEN → SFO
- Departs
- 11:21
- Flights
- 310
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s UA 1561, check with United Airlines.
UA 1561 draws a C+. About one flight in three arrives at least 15 minutes late, and the typical late arrival is roughly 45 minutes behind schedule. Build slack into anything you connect to. That rests on 310 flights, with a median arrival 1 minute early.
The national on-time rate over the same period is 77.3%, so UA 1561 runs 11 points behind the country as a whole. Across a thousand flights that is about 105 extra late arrivals.
Key figures
On time
66.8%
Arrivals under 15 minutes late, of 310 completed flights
Avg delay
43 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.89%
1 hour+ late
5.5%
National rate is 8.3%
These figures cover 310 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 1561 flies
UA 1561 flies DEN to SFO without a single fixed slot. Its most common scheduled departure was 11:21, used on 93 of 310 flights, with 11:35 (80 flights) and 11:20 (42 flights) next.
- Departs 11:2193 flights30.0%
- Departs 11:3580 flights25.8%
- Departs 11:2042 flights13.5%
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 11:21 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.3%, and UA 1561 runs 12 points worse at 66.8%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.
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Against the route
UA 1561 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 1561 is 4 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 12 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 1561thin sample | 310 | 66.8% | 43 min | 0.00% | 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 1561 quarter by quarter
UA 1561 did not run the same all year. Its best quarter was Jan–Mar 2026 at 81.1% on time and its weakest Apr–Jun 2026 at 54.9%, a swing of 26 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.
- Oct–Dec 202567 flights73.1%
- Jan–Mar 202690 flights81.1%
- Apr–Jun 202691 flights54.9%
- Jul–Sep 202662 flights56.5%
Scale runs 45% to 85%.
By weekday, UA 1561 did best on Saturday at 75.0% on time and worst on Monday at 57.8%. Each day rests on about 44 flights, so a gap of 17 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late UA 1561 runs when it is late
The 103 late arrivals split 50 under half an hour, 36 between 30 and 60 minutes, and 17 an hour or more.
- 15+ min early76 flights24.5%
- Within 15 min131 flights42.3%
- 15–29 min late50 flights16.1%
- 30–59 min late36 flights11.6%
- 1–2 hours late12 flights3.9%
- 2+ hours late5 flights1.6%
Scale runs 0% to 100%.
Share of 310 completed flights by arrival against schedule.
12 of 71 late departures made up the time and arrived on time, 17% of them. In the other direction, 44 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 1561
The latest arrival of the period was on 2 August 2026, 3 hours 26 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 2 August 2026 | 3 hours 26 minutes | Carrier |
| 30 May 2026 | 3 hours 24 minutes | Carrier |
| 19 December 2025 | 3 hours 15 minutes | Carrier |
| 20 April 2026 | 2 hours 42 minutes | National Airspace System |
| 28 May 2026 | 2 hours 10 minutes | National Airspace System |
Delay causes
Why UA 1561 runs late
National Airspace System accounts for 63% of the 4,419 delay minutes carriers reported here, and the remaining four split what is left.
- 63%National Airspace System
- 20%Carrier
- 17%Late-arriving aircraft
63% 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 2,804 minutes out of 4,419, against a national NAS share of 21%. The split is drawn from 4,419 delay minutes reported on UA 1561.
Cancellations are rare at 0.00%, below the national 1.89% and low enough to earn the plus on the grade. Almost no flights are called off; the risk here is arriving late, not not arriving.
Connections and routes
What a delay on this flight costs
5.5% 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 45 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 eight other city pairs in the data, including SFO to PHX (164), SFO to SAN (102) and SFO to ONT (76), but none flew often enough under UA 1561 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. 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 1561
For a booking, read UA 1561 as 66.8% on time with 0.00% cancelled over 310 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 2391 on the same route71.7%
- United Airlines 2367 on the same route95.3%
- United Airlines 1007 on the same route66.2%
- 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.