Flight number record
UA 1587
United Airlines · Washington to Denver
- Route
- IAD → DEN
- Departs
- 12:35
- Flights
- 291
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s UA 1587, check with United Airlines.
UA 1587 earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 14 points better than the national rate of 77.6%. When something does go wrong the average delay runs an hour and a half. That rests on 291 flights, with a median arrival 11 minutes early.
Set against the rest of the country, UA 1587's record is 14 points better than the US average of 77.6%. That gap is worth roughly 144 fewer late arrivals for every thousand flights.
Key figures
On time
92.0%
Arrivals under 15 minutes late, of 288 completed flights
Avg delay
91 min
Across delayed arrivals only, not all flights
Cancelled
0.34%
National rate is 1.81%
1 hour+ late
3.1%
National rate is 8.1%
These figures cover 291 flights between July 2025 and June 2026. The median arrival is 11 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 1587 flies
UA 1587 flies IAD to DEN without a single fixed slot. Its most common scheduled departure was 12:35, used on 69 of 291 flights, with 12:40 (56 flights) and 12:50 (49 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 12:3569 flights23.7%
- Departs 12:4056 flights19.2%
- Departs 12:5049 flights16.8%
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 12:35 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.8%, and UA 1587 runs 13 points better at 92.0%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.
Against the route
UA 1587 next to IAD to DEN
Every carrier on IAD to DEN combined arrived on time 81.7% of the time across 3,560 flights, so UA 1587 is 10 points ahead of it. United flew 2,798 flights on the same city pair under all its flight numbers, including this one, and those ran 83.2% on time. Across its whole network United Airlines managed 79.0%, which this flight beats by 13 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 1587thin sample | 291 | 92.0% | 91 min | 0.34% | A+ |
| All United Airlines on IAD–DEN | 2,798 | 83.2% | 71 min | 0.46% | B+ |
| All carriers on IAD–DEN | 3,560 | 81.7% | 66 min | 0.62% | B+ |
| United Airlines, whole network | 821,041 | 79.0% | 72 min | 1.01% | B |
Across the year
UA 1587 quarter by quarter
UA 1587 did not run the same all year. Its best quarter was Oct–Dec 2025 at 94.7% on time and its weakest Jan–Mar 2026 at 81.2%, a swing of 14 points on roughly 73 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 flights92.1%
- Oct–Dec 202576 flights94.7%
- Jan–Mar 202632 flights81.2%
- Apr–Jun 202691 flights93.4%
Scale runs 75% to 100%. Rows with fewer than 30 flights show a dash.
By weekday, UA 1587 ranged from 85.4% on Tuesday to 95.1% on Sunday. With about 42 flights behind each day, a spread of 10 points is inside normal variation, so the day you fly is not worth changing for this flight.
Delay causes
Why UA 1587 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 2,085 reported delay minutes.
- 38%Late-arriving aircraft
- 30%National Airspace System
- 17%Carrier
- 15%Extreme weather
Extreme weather accounts for 15% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the quarterly figures above are the more useful view of the risk. The national share is 6%, so this operation carries roughly 2.4 times the usual weather exposure. The split is drawn from 2,085 delay minutes reported on UA 1587.
Cancellations are rare at 0.34%, 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
Badly late arrivals are rare here: only 3.1% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
The 1,452 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 five other city pairs in the data, including DEN to IAH (125), DEN to BOS (52) and DEN to OMA (23), but none flew often enough under UA 1587 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to IAD to DEN only.
One caution: this is a thin sample. 291 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 1587
For a booking, UA 1587 has one of the better records a US domestic flight can show: 92.0% on time and 0.34% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- IAD to DEN, every carrier and departure
- DEN to IAD, the return direction
- United Airlines 495 on the same route82.5%
- Washington Dulles International (IAD) 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.