Flight number record
UA 531
United Airlines · Denver to Los Angeles
- Route
- DEN → LAX
- Departs
- 21:20
- Flights
- 286
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s UA 531, check with United Airlines.
UA 531 lands a B+, 3 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 286 flights, with a median arrival 4 minutes early.
Key figures
On time
80.1%
Arrivals under 15 minutes late, of 286 completed flights
Avg delay
62 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.81%
1 hour+ late
6.3%
National rate is 8.1%
These figures cover 286 flights between July 2025 and June 2026. The median arrival is 4 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 531 flies
UA 531 flies DEN to LAX without a single fixed slot. Its most common scheduled departure was 21:20, used on 62 of 286 flights, with 20:50 (37 flights) and 21:28 (31 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 21:2062 flights21.7%
- Departs 20:5037 flights12.9%
- Departs 21:2831 flights10.8%
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 21:20 departure sits in the 8pm–5am window. Across every US flight scheduled in that window the on-time rate is 70.5%, and UA 531 runs 10 points better at 80.1%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.
Against the route
UA 531 next to DEN to LAX
Every carrier on DEN to LAX combined arrived on time 79.0% of the time across 7,721 flights, so UA 531 is about level with it. United flew 3,064 flights on the same city pair under all its flight numbers, including this one, and those ran 84.5% on time. Across its whole network United Airlines managed 79.0%, close to this flight's figure.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 531thin sample | 286 | 80.1% | 62 min | 0.00% | B+ |
| All United Airlines on DEN–LAX | 3,064 | 84.5% | 58 min | 0.00% | B+ |
| All carriers on DEN–LAX | 7,721 | 79.0% | 62 min | 0.51% | B+ |
| United Airlines, whole network | 821,041 | 79.0% | 72 min | 1.01% | 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 2025 at 69.4%, a swing of 14 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 202549 flights69.4%
- Oct–Dec 202566 flights83.3%
- Jan–Mar 202684 flights83.3%
- Apr–Jun 202687 flights80.5%
Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.
By weekday, UA 531 did best on Saturday at 92.1% on time and worst on Friday at 71.1%. Each day rests on about 41 flights, so a gap of 21 points is worth noticing but could still narrow in another year.
Delay causes
Why UA 531 runs late
One category carries most of the weight here. Late-arriving aircraft accounts for 42% of the 3,518 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.
- 42%Late-arriving aircraft
- 40%Carrier
- 15%National Airspace System
- 2%Extreme weather
42% 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 3,518 reported delay minutes here, that single category outweighs weather by 19 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 3,518 delay minutes reported on UA 531.
Cancellations are rare at 0.00%, below the national 1.81% 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
6.3% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says 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. 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 eight other city pairs in the data, including MCO to DEN (102), MSY to DEN (48) and JAC to DEN (47), 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. 286 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 80.1% on time with 0.00% cancelled over 286 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 route91.2%
- United Airlines 1013 on the same route86.3%
- United Airlines 405 on the same route91.0%
- United Airlines 2240 on the same route75.9%
- Frontier Airlines 4345 on the same route71.3%
- Frontier Airlines 2341 on the same route89.3%
- 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.