Flight number record
UA 647
United Airlines · Boston to Denver
- Route
- BOS → DEN
- Departs
- 07:45
- Flights
- 364
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s UA 647, check with United Airlines.
UA 647 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 13 points better than the national rate of 77.3%. When something does go wrong the average delay runs about 40 minutes. That rests on 364 flights, with a median arrival 10 minutes early.
Set against the rest of the country, UA 647's record is 13 points better than the US average of 77.3%. That gap is worth roughly 132 fewer late arrivals for every thousand flights.
Key figures
On time
90.5%
Arrivals under 15 minutes late, of 357 completed flights
Avg delay
39 min
Across delayed arrivals only, not all flights
Cancelled
1.92%
National rate is 1.89%
1 hour+ late
1.7%
National rate is 8.3%
These figures cover 364 flights between September 2025 and August 2026. The median arrival is 10 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 647 flies
UA 647 flies BOS to DEN without a single fixed slot. Its most common scheduled departure was 07:45, used on 99 of 364 flights, with 07:25 (73 flights) and 07:30 (55 flights) next.
- Departs 07:4599 flights27.2%
- Departs 07:2573 flights20.1%
- Departs 07:3055 flights15.1%
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 07:45 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and UA 647 runs level with that at 90.5%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
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Against the route
UA 647 next to BOS to DEN
Every carrier on BOS to DEN combined arrived on time 75.7% of the time across 3,847 flights, so UA 647 is 15 points ahead of it. United flew 1,884 flights on the same city pair under all its flight numbers, including this one, and those ran 82.5% on time. Across its whole network United Airlines managed 78.8%, which this flight beats by 12 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 647thin sample | 364 | 90.5% | 39 min | 1.92% | A |
| All United Airlines on BOS–DEN | 1,884 | 82.5% | 70 min | 1.11% | B |
| All carriers on BOS–DEN | 3,847 | 75.7% | 62 min | 1.38% | B |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | B |
Across the year
UA 647 quarter by quarter
UA 647 did not run the same all year. Its best quarter was Apr–Jun 2026 at 96.7% on time and its weakest Jan–Mar 2026 at 85.7%, a swing of 11 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 202530 flights90.0%
- Oct–Dec 202592 flights89.0%
- Jan–Mar 202689 flights85.7%
- Apr–Jun 202691 flights96.7%
- Jul–Sep 202662 flights90.2%
Scale runs 75% to 100%.
By weekday, UA 647 ranged from 88.2% on Saturday to 93.9% on Wednesday. With about 52 flights behind each day, a spread of 6 points is inside normal variation, so the day you fly is not worth changing for this flight.
Arrival by arrival
How late UA 647 runs when it is late
UA 647 often beats the schedule: 125 of 357 completed flights, 35%, arrived 15 minutes or more early. The 34 late arrivals split 14 under half an hour, 14 between 30 and 60 minutes, and 6 an hour or more.
- 15+ min early125 flights35.0%
- Within 15 min198 flights55.5%
- 15–29 min late14 flights3.9%
- 30–59 min late14 flights3.9%
- 1–2 hours late5 flights1.4%
- 2+ hours late1 flights0.3%
Scale runs 0% to 100%.
Share of 357 completed flights by arrival against schedule.
5 of 21 late departures made up the time and arrived on time, 24% 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 DEN.
The worst days
Worst days for UA 647
The latest arrival of the period was on 27 January 2026, 2 hours 21 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 |
|---|---|---|
| 27 January 2026 | 2 hours 21 minutes | Carrier |
| 26 September 2025 | 1 hour 50 minutes | Carrier |
| 18 June 2026 | 1 hour 34 minutes | Carrier |
| 11 November 2025 | 1 hour 17 minutes | Carrier |
| 28 December 2025 | 1 hour 7 minutes | National Airspace System |
Delay causes
Why UA 647 runs late
Carrier accounts for 54% of the 1,337 delay minutes carriers reported here, and the remaining four split what is left.
- 54%Carrier
- 41%National Airspace System
- 4%Extreme weather
- 2%Late-arriving aircraft
41% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 542 minutes out of 1,337, against a national NAS share of 21%. The split is drawn from 1,337 delay minutes reported on UA 647.
Cancellations sit at 1.92% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
Badly late arrivals are rare here: only 1.7% 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.
At 1,754 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The same number turns up on one other city pair in the data, including TYS to DEN (1), but none flew often enough under UA 647 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to BOS to DEN only.
One caution: this is a thin sample. 364 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 647
For a booking, read UA 647 as 90.5% on time with 1.92% cancelled over 364 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- BOS to DEN, every carrier and departure
- DEN to BOS, the return direction
- Delta Air Lines 499 on the same route83.6%
- United Airlines 414 on the same route89.4%
- United Airlines 2297 on the same route85.1%
- United Airlines 800 on the same route72.9%
- JetBlue Airways 993 on the same route57.2%
- United Airlines 662 on the same route89.3%
- Boston Logan International (BOS) 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
- 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.