Flight number record
UA 644
United Airlines · Denver to Portland
- Route
- DEN → PDX
- Departs
- 11:50
- Flights
- 312
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s UA 644, check with United Airlines.
UA 644 earns a B+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 points better than the national rate of 77.3%. When something does go wrong the average delay runs roughly 45 minutes. That rests on 312 flights, with a median arrival 5 minutes early.
Set against the rest of the country, UA 644's record is 7 points better than the US average of 77.3%. That gap is worth roughly 70 fewer late arrivals for every thousand flights.
Key figures
On time
84.3%
Arrivals under 15 minutes late, of 312 completed flights
Avg delay
47 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.89%
1 hour+ late
3.2%
National rate is 8.3%
These figures cover 312 flights between September 2025 and August 2026. The median arrival is 5 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 644 flies
UA 644 flies DEN to PDX without a single fixed slot. Its most common scheduled departure was 11:50, used on 82 of 312 flights, with 11:27 (59 flights) and 11:20 (55 flights) next.
- Departs 11:5082 flights26.3%
- Departs 11:2759 flights18.9%
- Departs 11:2055 flights17.6%
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 11:50 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.3%, and UA 644 runs 6 points better at 84.3%. 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 644 next to DEN to PDX
Every carrier on DEN to PDX combined arrived on time 74.8% of the time across 4,280 flights, so UA 644 is 10 points ahead of it. United flew 1,822 flights on the same city pair under all its flight numbers, including this one, and those ran 82.3% on time. Across its whole network United Airlines managed 78.8%, which this flight beats by 6 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 644thin sample | 312 | 84.3% | 47 min | 0.00% | B+ |
| All United Airlines on DEN–PDX | 1,822 | 82.3% | 59 min | 0.38% | B+ |
| All carriers on DEN–PDX | 4,280 | 74.8% | 55 min | 0.33% | C+ |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | B |
Across the year
UA 644 quarter by quarter
Quarter by quarter UA 644 held fairly steady: 90.0% in Jul–Sep 2025, 84.6% in Oct–Dec 2025, 83.3% in Jan–Mar 2026, 82.4% in Apr–Jun 2026 and 85.5% in Jul–Sep 2026. A spread of 8 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.
- Jul–Sep 202530 flights90.0%
- Oct–Dec 202539 flights84.6%
- Jan–Mar 202690 flights83.3%
- Apr–Jun 202691 flights82.4%
- Jul–Sep 202662 flights85.5%
Scale runs 75% to 95%.
By weekday, UA 644 did best on Monday at 91.1% on time and worst on Wednesday at 77.3%. Each day rests on about 45 flights, so a gap of 14 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late UA 644 runs when it is late
The 49 late arrivals split 19 under half an hour, 20 between 30 and 60 minutes, and 10 an hour or more.
- 15+ min early48 flights15.4%
- Within 15 min215 flights68.9%
- 15–29 min late19 flights6.1%
- 30–59 min late20 flights6.4%
- 1–2 hours late6 flights1.9%
- 2+ hours late4 flights1.3%
Scale runs 0% to 100%.
Share of 312 completed flights by arrival against schedule.
6 of 37 late departures made up the time and arrived on time, 16% of them. In the other direction, 18 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 PDX.
The worst days
Worst days for UA 644
The latest arrival of the period was on 25 January 2026, 3 hours 50 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on four of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 25 January 2026 | 3 hours 50 minutes | Carrier |
| 13 September 2025 | 2 hours 30 minutes | Late-arriving aircraft |
| 31 January 2026 | 2 hours 12 minutes | Carrier |
| 18 June 2026 | 2 hours 11 minutes | Carrier |
| 1 August 2026 | 1 hour 38 minutes | Carrier |
Delay causes
Why UA 644 runs late
Carrier accounts for 51% of the 2,317 delay minutes carriers reported here, and the remaining four split what is left.
- 51%Carrier
- 25%National Airspace System
- 22%Late-arriving aircraft
- 2%Extreme weather
The largest share of delay minutes, 51%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,178 of the 2,317 delay minutes reported here. The split is drawn from 2,317 delay minutes reported on UA 644.
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 3.2% 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 991 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 nine other city pairs in the data, including DFW to DEN (124), BNA to IAH (52) and PDX to SFO (27), but none flew often enough under UA 644 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to DEN to PDX only.
One caution: this is a thin sample. 312 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 644
For a booking, read UA 644 as 84.3% on time with 0.00% cancelled over 312 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- DEN to PDX, every carrier and departure
- PDX to DEN, the return direction
- United Airlines 498 on the same route77.4%
- United Airlines 1247 on the same route87.8%
- United Airlines 1337 on the same route83.4%
- Denver International (DEN) delay statistics
- Portland International (PDX) 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
- Worst months to fly in the US, ranked by the data
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.