Flight number record
UA 519
United Airlines · San Diego to Denver
- Route
- SAN → DEN
- Departs
- 18:55
- Flights
- 259
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s UA 519, check with United Airlines.
UA 519 earns an A. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 9 points better than the national rate of 77.3%. When something does go wrong the average delay runs about an hour. That rests on 259 flights, with a median arrival 18 minutes early.
Set against the rest of the country, UA 519's record is 9 points better than the US average of 77.3%. That gap is worth roughly 90 fewer late arrivals for every thousand flights.
Key figures
On time
86.3%
Arrivals under 15 minutes late, of 256 completed flights
Avg delay
65 min
Across delayed arrivals only, not all flights
Cancelled
1.16%
National rate is 1.89%
1 hour+ late
5.5%
National rate is 8.3%
These figures cover 259 flights between September 2025 and August 2026. The median arrival is 18 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 519 flies
UA 519 flies SAN to DEN without a single fixed slot. Its most common scheduled departure was 18:55, used on 139 of 259 flights, with 19:14 (28 flights) and 18:47 (27 flights) next.
- Departs 18:55139 flights53.7%
- Departs 19:1428 flights10.8%
- Departs 18:4727 flights10.4%
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 18:55 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.0%, and UA 519 runs 18 points better at 86.3%. 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 519 next to SAN to DEN
Every carrier on SAN to DEN combined arrived on time 78.4% of the time across 6,134 flights, so UA 519 is 8 points ahead of it. United flew 2,067 flights on the same city pair under all its flight numbers, including this one, and those ran 85.7% on time. Across its whole network United Airlines managed 78.8%, which this flight beats by 8 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 519thin sample | 259 | 86.3% | 65 min | 1.16% | A |
| All United Airlines on SAN–DEN | 2,067 | 85.7% | 72 min | 0.63% | A+ |
| All carriers on SAN–DEN | 6,134 | 78.4% | 63 min | 1.03% | B |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | B |
Across the year
UA 519 quarter by quarter
UA 519 did not run the same all year. Its best quarter was Jan–Mar 2026 at 92.6% on time and its weakest Jul–Sep 2026 at 69.0%, a swing of 24 points on roughly 65 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 202521 flights—
- Oct–Dec 202568 flights91.2%
- Jan–Mar 202656 flights92.6%
- Apr–Jun 202672 flights90.3%
- Jul–Sep 202642 flights69.0%
Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.
By weekday, UA 519 did best on Monday at 92.5% on time and worst on Thursday at 77.6%. Each day rests on about 37 flights, so a gap of 15 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late UA 519 runs when it is late
UA 519 often beats the schedule: 155 of 256 completed flights, 61%, arrived 15 minutes or more early. The 35 late arrivals split 12 under half an hour, 9 between 30 and 60 minutes, and 14 an hour or more.
- 15+ min early155 flights60.5%
- Within 15 min66 flights25.8%
- 15–29 min late12 flights4.7%
- 30–59 min late9 flights3.5%
- 1–2 hours late10 flights3.9%
- 2+ hours late4 flights1.6%
Scale runs 0% to 100%.
Share of 256 completed flights by arrival against schedule.
8 of 38 late departures made up the time and arrived on time, 21% of them. Only 5 left on time and still arrived late.
The worst days
Worst days for UA 519
The latest arrival of the period was on 25 June 2026, 3 hours 38 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on four of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 25 June 2026 | 3 hours 38 minutes | Late-arriving aircraft |
| 3 June 2026 | 3 hours | Late-arriving aircraft |
| 13 August 2026 | 2 hours 41 minutes | National Airspace System |
| 2 August 2026 | 2 hours 14 minutes | Late-arriving aircraft |
| 1 May 2026 | 1 hour 53 minutes | Late-arriving aircraft |
Delay causes
Why UA 519 runs late
Late-arriving aircraft accounts for 73% of the 2,256 delay minutes carriers reported here, and the remaining four split what is left.
- 73%Late-arriving aircraft
- 25%National Airspace System
- 3%Carrier
73% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 2,256 reported delay minutes here, that single category outweighs weather by 73 to one. The split is drawn from 2,256 delay minutes reported on UA 519.
Cancellations sit at 1.16% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
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 about an hour, which a normal layover absorbs.
The 853 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 eleven other city pairs in the data, including DEN to MCO (82), DEN to FLL (11) and IAD to CLT (9), but none flew often enough under UA 519 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to SAN to DEN only.
One caution: this is a thin sample. 259 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 519
For a booking, UA 519 has one of the better records a US domestic flight can show: 86.3% on time and 1.16% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- SAN to DEN, every carrier and departure
- DEN to SAN, the return direction
- United Airlines 2476 on the same route88.7%
- United Airlines 682 on the same route73.9%
- Frontier Airlines 2818 on the same route85.9%
- United Airlines 1337 on the same route89.4%
- San Diego International (SAN) 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.