Flight number record
UA 1587
United Airlines · Washington to Denver
- Route
- IAD → DEN
- Departs
- 12:48
- Flights
- 291
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 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 77.3%. When something does go wrong the average delay runs a little over an hour. That rests on 291 flights, with a median arrival 12 minutes early.
Set against the rest of the country, UA 1587's record is 14 points better than the US average of 77.3%. That gap is worth roughly 144 fewer late arrivals for every thousand flights.
Key figures
On time
91.7%
Arrivals under 15 minutes late, of 290 completed flights
Avg delay
80 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.89%
1 hour+ late
3.4%
National rate is 8.3%
These figures cover 291 flights between September 2025 and August 2026. The median arrival is 12 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 1587 flies
UA 1587 flies IAD to DEN without a single fixed slot. Its most common scheduled departure was 12:48, used on 82 of 291 flights, with 12:40 (56 flights) and 12:35 (56 flights) next.
- Departs 12:4882 flights28.2%
- Departs 12:4056 flights19.2%
- Departs 12:3556 flights19.2%
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 12:48 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.3%, and UA 1587 runs 13 points better at 91.7%. 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 1587 next to IAD to DEN
Every carrier on IAD to DEN combined arrived on time 83.1% of the time across 3,387 flights, so UA 1587 is 9 points ahead of it. United flew 2,791 flights on the same city pair under all its flight numbers, including this one, and those ran 84.1% on time. Across its whole network United Airlines managed 78.8%, which this flight beats by 13 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 1587thin sample | 291 | 91.7% | 80 min | 0.00% | A+ |
| All United Airlines on IAD–DEN | 2,791 | 84.1% | 68 min | 0.50% | B+ |
| All carriers on IAD–DEN | 3,387 | 83.1% | 63 min | 0.59% | B+ |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | B |
Across the year
UA 1587 quarter by quarter
UA 1587 did not run the same all year. Its best quarter was Jul–Sep 2025 at 96.7% on time and its weakest Jan–Mar 2026 at 81.2%, a swing of 16 points on roughly 58 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 202530 flights96.7%
- Oct–Dec 202576 flights94.7%
- Jan–Mar 202632 flights81.2%
- Apr–Jun 202691 flights93.4%
- Jul–Sep 202662 flights88.5%
Scale runs 75% to 100%.
By weekday, UA 1587 ranged from 90.0% on Wednesday to 95.1% on Saturday. With about 42 flights behind each day, a spread of 5 points is inside normal variation, so the day you fly is not worth changing for this flight.
Arrival by arrival
How late UA 1587 runs when it is late
UA 1587 often beats the schedule: 125 of 290 completed flights, 43%, arrived 15 minutes or more early. The 24 late arrivals split 8 under half an hour, 6 between 30 and 60 minutes, and 10 an hour or more.
- 15+ min early125 flights43.1%
- Within 15 min141 flights48.6%
- 15–29 min late8 flights2.8%
- 30–59 min late6 flights2.1%
- 1–2 hours late7 flights2.4%
- 2+ hours late3 flights1.0%
Scale runs 0% to 100%.
Share of 290 completed flights by arrival against schedule.
A late pushback is often recovered here: of 25 departures that left 15 minutes late or more, 12 still arrived on time. 11 flights left on time and still arrived late.
The worst days
Worst days for UA 1587
The latest arrival of the period was on 31 December 2025, 8 hours 54 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. Three of the five worst days fell in March 2026.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 31 December 2025 | 8 hours 54 minutes | Late-arriving aircraft |
| 28 March 2026 | 3 hours 2 minutes | Late-arriving aircraft |
| 14 March 2026 | 2 hours 29 minutes | Carrier |
| 3 July 2026 | 1 hour 57 minutes | Carrier |
| 12 March 2026 | 1 hour 56 minutes | National Airspace System |
Delay causes
Why UA 1587 runs late
Late-arriving aircraft accounts for 46% of the 1,912 delay minutes carriers reported here, and the remaining four split what is left.
- 46%Late-arriving aircraft
- 33%National Airspace System
- 21%Carrier
46% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 1,912 reported delay minutes here, that single category outweighs weather by 46 to one. The split is drawn from 1,912 delay minutes reported on UA 1587.
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
Badly late arrivals are rare here: only 3.4% land an hour or more behind schedule, against 8.3% 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.
The same number turns up on five other city pairs in the data, including DEN to IAH (146), 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: 91.7% on time and 0.00% 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 route85.4%
- United Airlines 599 on the same route69.4%
- 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.