Flight number record
UA 647
United Airlines · Boston to Denver
- Route
- BOS → DEN
- Departs
- 07:30
- Flights
- 364
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 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 14 points better than the national rate of 77.6%. When something does go wrong the average delay runs roughly 45 minutes. That rests on 364 flights, with a median arrival 9 minutes early.
Set against the rest of the country, UA 647's record is 14 points better than the US average of 77.6%. That gap is worth roughly 135 fewer late arrivals for every thousand flights.
Key figures
On time
91.1%
Arrivals under 15 minutes late, of 358 completed flights
Avg delay
44 min
Across delayed arrivals only, not all flights
Cancelled
1.65%
National rate is 1.81%
1 hour+ late
2.0%
National rate is 8.1%
These figures cover 364 flights between July 2025 and June 2026. The median arrival is 9 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 647 flies
UA 647 flies BOS to DEN without a single fixed slot. Its most common scheduled departure was 07:30, used on 117 of 364 flights, with 07:25 (73 flights) and 07:09 (53 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 07:30117 flights32.1%
- Departs 07:2573 flights20.1%
- Departs 07:0953 flights14.6%
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 07:30 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 91.1%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
Against the route
UA 647 next to BOS to DEN
Every carrier on BOS to DEN combined arrived on time 76.5% of the time across 3,899 flights, so UA 647 is 15 points ahead of it. United flew 1,908 flights on the same city pair under all its flight numbers, including this one, and those ran 83.0% on time. Across its whole network United Airlines managed 79.0%, which this flight beats by 12 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 647thin sample | 364 | 91.1% | 44 min | 1.65% | A |
| All United Airlines on BOS–DEN | 1,908 | 83.0% | 64 min | 1.00% | B |
| All carriers on BOS–DEN | 3,899 | 76.5% | 58 min | 1.18% | B |
| United Airlines, whole network | 821,041 | 79.0% | 72 min | 1.01% | 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 91 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 flights92.4%
- Oct–Dec 202592 flights89.0%
- Jan–Mar 202689 flights85.7%
- Apr–Jun 202691 flights96.7%
Scale runs 75% to 100%. Rows with fewer than 30 flights show a dash.
By weekday, UA 647 ranged from 86.5% on Saturday to 93.9% on Wednesday. With about 52 flights behind each day, a spread of 7 points is inside normal variation, so the day you fly is not worth changing for this flight.
Delay causes
Why UA 647 runs late
One category carries most of the weight here. Carrier accounts for 62% of the 1,397 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 62%Carrier
- 33%National Airspace System
- 3%Extreme weather
- 2%Late-arriving aircraft
33% 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 461 minutes out of 1,397, against a national NAS share of 21%. The split is drawn from 1,397 delay minutes reported on UA 647.
Cancellations sit at 1.65% against a national 1.81%, 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 2.0% 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.
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 91.1% on time with 1.65% 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 route84.7%
- United Airlines 2297 on the same route84.3%
- United Airlines 414 on the same route90.0%
- JetBlue Airways 393 on the same route79.6%
- United Airlines 662 on the same route92.0%
- JetBlue Airways 993 on the same route59.3%
- 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.