Flight number record
UA 800
United Airlines · Boston to Denver
- Route
- BOS → DEN
- Departs
- 16:50
- Flights
- 284
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s UA 800, check with United Airlines.
UA 800 sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 4 points worse than the national rate of 77.3%. The late ones land about an hour behind schedule. That rests on 284 flights, with a median arrival 2 minutes early.
The national on-time rate over the same period is 77.3%, so UA 800 runs 4 points behind the country as a whole. Across a thousand flights that is about 44 extra late arrivals.
Key figures
On time
72.9%
Arrivals under 15 minutes late, of 280 completed flights
Avg delay
64 min
Across delayed arrivals only, not all flights
Cancelled
1.06%
National rate is 1.89%
1 hour+ late
9.6%
National rate is 8.3%
These figures cover 284 flights between September 2025 and August 2026. Beyond the headline rate, 9.6% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When UA 800 flies
UA 800 flies BOS to DEN without a single fixed slot. Its most common scheduled departure was 16:50, used on 86 of 284 flights, with 16:57 (81 flights) and 16:49 (40 flights) next.
- Departs 16:5086 flights30.3%
- Departs 16:5781 flights28.5%
- Departs 16:4940 flights14.1%
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 16:50 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 71.9%, and UA 800 runs level with that at 72.9%. 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 800 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 800 is 3 points behind 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 trails by 6 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 800thin sample | 284 | 72.9% | 64 min | 1.06% | C |
| 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 800 quarter by quarter
UA 800 did not run the same all year. Its best quarter was Jan–Mar 2026 at 82.9% on time and its weakest Jul–Sep 2026 at 54.4%, a swing of 29 points on roughly 71 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.
- Oct–Dec 202556 flights76.8%
- Jan–Mar 202679 flights82.9%
- Apr–Jun 202691 flights73.6%
- Jul–Sep 202658 flights54.4%
Scale runs 45% to 90%.
By weekday, UA 800 did best on Tuesday at 81.6% on time and worst on Thursday at 61.9%. Each day rests on about 41 flights, so a gap of 20 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late UA 800 runs when it is late
The 76 late arrivals split 25 under half an hour, 24 between 30 and 60 minutes, and 27 an hour or more.
- 15+ min early59 flights21.1%
- Within 15 min145 flights51.8%
- 15–29 min late25 flights8.9%
- 30–59 min late24 flights8.6%
- 1–2 hours late20 flights7.1%
- 2+ hours late7 flights2.5%
Scale runs 0% to 100%.
Share of 280 completed flights by arrival against schedule.
Time lost at the gate mostly stays lost. Of 56 departures that left 15 minutes late or more, only 4 made it up before arrival. In the other direction, 24 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 800
The latest arrival of the period was on 28 November 2025, 6 hours 49 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on four of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 28 November 2025 | 6 hours 49 minutes | Late-arriving aircraft |
| 19 December 2025 | 5 hours 40 minutes | Late-arriving aircraft |
| 28 July 2026 | 3 hours 39 minutes | National Airspace System |
| 30 October 2025 | 2 hours 47 minutes | Late-arriving aircraft |
| 10 November 2025 | 2 hours 37 minutes | Late-arriving aircraft |
Delay causes
Why UA 800 runs late
Late-arriving aircraft accounts for 48% of the 4,831 delay minutes carriers reported here, and the remaining four split what is left.
- 48%Late-arriving aircraft
- 40%National Airspace System
- 11%Carrier
- 1%Extreme weather
48% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 4,831 reported delay minutes here, that single category outweighs weather by 48 to one. The split is drawn from 4,831 delay minutes reported on UA 800.
Cancellations sit at 1.06% against a national 1.89%, which is ordinary. Diversions add another 0.35%.
Connections and routes
What a delay on this flight costs
9.6% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
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 three other city pairs in the data, including IAH to BOS (55), OMA to IAH (23) and DEN to TPA (2), but none flew often enough under UA 800 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. 284 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 800
For a booking, read UA 800 as 72.9% on time with 1.06% cancelled over 284 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 647 on the same route90.5%
- United Airlines 2297 on the same route85.1%
- 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
- 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.