Flight number record

UA 800

United Airlines · Boston to Denver

Route: BOS → DEN
Departs: 16:57
Flights: 275
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 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, 5 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 275 flights, with a median arrival 2 minutes early.

The national on-time rate over the same period is 77.6%, so UA 800 runs 5 points behind the country as a whole. Across a thousand flights that is about 48 extra late arrivals.

On time

72.8%

Arrivals under 15 minutes late, of 272 completed flights

Avg delay

64 min

Across delayed arrivals only, not all flights

Cancelled

1.09%

National rate is 1.81%

1 hour+ late

9.2%

National rate is 8.1%

These figures cover 275 flights between July 2025 and June 2026. Beyond the headline rate, 9.2% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.

Schedule

When UA 800 flies

UA 800 flies BOS to DEN without a single fixed slot. Its most common scheduled departure was 16:57, used on 90 of 275 flights, with 16:50 (86 flights) and 16:49 (40 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 16:5790 flights32.7%
Departs 16:5086 flights31.3%
Departs 16:4940 flights14.5%

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 16:57 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 72.4%, and UA 800 runs level with that at 72.8%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

Against the route

UA 800 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 800 is 4 points behind 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 trails by 6 points.

UA 800 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
UA 800thin sample	275	72.8%	64 min	1.09%	C
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 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 2025 at 51.0%, a swing of 32 points on roughly 69 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 202549 flights51.0%
Oct–Dec 202556 flights76.8%
Jan–Mar 202679 flights82.9%
Apr–Jun 202691 flights73.6%

Scale runs 45% to 90%. Rows with fewer than 30 flights show a dash.

By weekday, UA 800 did best on Saturday at 83.3% on time and worst on Thursday at 56.1%. Each day rests on about 39 flights, so a gap of 27 points is worth noticing but could still narrow in another year.

Delay causes

Why UA 800 runs late

One category carries most of the weight here. Late-arriving aircraft accounts for 47% of the 4,761 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.

Late-arriving aircraft
47%
National Airspace System
33%
Carrier
12%
Extreme weather
8%

47% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 4,761 reported delay minutes here, that single category outweighs weather by 6 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 4,761 delay minutes reported on UA 800.

Cancellations sit at 1.09% against a national 1.81%, which is ordinary. Diversions add another 0.00%.

Connections and routes

What a delay on this flight costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.2% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum 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 (68), 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. 275 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 72.8% on time with 1.09% cancelled over 275 flights. Those are rates from the past twelve months, not a forecast for any particular day.

Where to go next

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.

Key figures