Flight number record
UA 531
United Airlines · Denver to Los Angeles
- Route
- DEN → LAX
- Departs
- 21:20
- Flights
- 316
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s UA 531, check with United Airlines.
UA 531 lands a B+, about a point worse than the national rate of 77.3%. About one flight in four arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 316 flights, with a median arrival 2 minutes early.
Key figures
On time
76.3%
Arrivals under 15 minutes late, of 316 completed flights
Avg delay
63 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.89%
1 hour+ late
8.2%
National rate is 8.3%
These figures cover 316 flights between September 2025 and August 2026. Beyond the headline rate, 8.2% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When UA 531 flies
UA 531 flies DEN to LAX without a single fixed slot. Its most common scheduled departure was 21:20, used on 103 of 316 flights, with 20:50 (37 flights) next.
- Departs 21:20103 flights32.6%
- Departs 20:5037 flights11.7%
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 21:20 departure sits in the 8pm–5am window. Across every US flight scheduled in that window the on-time rate is 70.1%, and UA 531 runs 6 points better at 76.3%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.
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Against the route
UA 531 next to DEN to LAX
Every carrier on DEN to LAX combined arrived on time 78.7% of the time across 7,708 flights, so UA 531 is 2 points behind it. United flew 3,079 flights on the same city pair under all its flight numbers, including this one, and those ran 84.0% on time. Across its whole network United Airlines managed 78.8%, which this flight trails by 3 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 531thin sample | 316 | 76.3% | 63 min | 0.00% | B+ |
| All United Airlines on DEN–LAX | 3,079 | 84.0% | 56 min | 0.00% | B+ |
| All carriers on DEN–LAX | 7,708 | 78.7% | 63 min | 0.53% | B+ |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | B |
Across the year
UA 531 quarter by quarter
UA 531 did not run the same all year. Its best quarter was Oct–Dec 2025 at 83.3% on time and its weakest Jul–Sep 2026 at 46.4%, a swing of 37 points on roughly 79 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 202523 flights—
- Oct–Dec 202566 flights83.3%
- Jan–Mar 202684 flights83.3%
- Apr–Jun 202687 flights80.5%
- Jul–Sep 202656 flights46.4%
Scale runs 40% to 90%. Rows with fewer than 30 flights show a dash.
By weekday, UA 531 did best on Saturday at 92.7% on time and worst on Monday at 66.7%. Each day rests on about 45 flights, so a gap of 26 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late UA 531 runs when it is late
The 75 late arrivals split 30 under half an hour, 19 between 30 and 60 minutes, and 26 an hour or more.
- 15+ min early66 flights20.9%
- Within 15 min175 flights55.4%
- 15–29 min late30 flights9.5%
- 30–59 min late19 flights6.0%
- 1–2 hours late20 flights6.3%
- 2+ hours late6 flights1.9%
Scale runs 0% to 100%.
Share of 316 completed flights by arrival against schedule.
15 of 67 late departures made up the time and arrived on time, 22% of them. In the other direction, 23 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 LAX.
The worst days
Worst days for UA 531
The latest arrival of the period was on 13 August 2026, 8 hours 10 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). Three of the five worst days fell in August 2026.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 13 August 2026 | 8 hours 10 minutes | Carrier |
| 14 August 2026 | 5 hours 51 minutes | Carrier |
| 28 July 2026 | 2 hours 36 minutes | Carrier |
| 3 August 2026 | 2 hours 8 minutes | Carrier |
| 17 December 2025 | 2 hours 5 minutes | Carrier |
Delay causes
Why UA 531 runs late
Late-arriving aircraft accounts for 46% of the 4,689 delay minutes carriers reported here, and the remaining four split what is left.
- 46%Late-arriving aircraft
- 38%Carrier
- 14%National Airspace System
- 2%Extreme weather
46% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 4,689 reported delay minutes here, that single category outweighs weather by 27 to one. The split is drawn from 4,689 delay minutes reported on UA 531.
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
8.2% 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 about an hour, which a normal layover absorbs.
The 862 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 JAC to DEN (87), MCO to DEN (53) and MSY to DEN (48), but none flew often enough under UA 531 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to DEN to LAX only.
One caution: this is a thin sample. 316 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 531
For a booking, read UA 531 as 76.3% on time with 0.00% cancelled over 316 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- DEN to LAX, every carrier and departure
- LAX to DEN, the return direction
- United Airlines 1638 on the same route91.8%
- United Airlines 1013 on the same route83.8%
- United Airlines 405 on the same route91.2%
- United Airlines 2240 on the same route75.3%
- United Airlines 1195 on the same route82.5%
- Frontier Airlines 4345 on the same route74.9%
- Denver International (DEN) delay statistics
- Los Angeles International (LAX) 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.