Flight number record

UA 597

United Airlines · Denver to Boston

Route: DEN → BOS
Departs: 14:10
Flights: 277
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s UA 597, check with United Airlines.

UA 597 sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 6 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 277 flights, with a median arrival 8 minutes early.

The national on-time rate over the same period is 77.6%, so UA 597 runs 6 points behind the country as a whole. Across a thousand flights that is about 63 extra late arrivals.

On time

71.3%

Arrivals under 15 minutes late, of 272 completed flights

Avg delay

77 min

Across delayed arrivals only, not all flights

Cancelled

1.44%

National rate is 1.81%

1 hour+ late

12.9%

National rate is 8.1%

These figures cover 277 flights between July 2025 and June 2026. Beyond the headline rate, 12.9% 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 597 flies

UA 597 flies DEN to BOS without a single fixed slot. Its most common scheduled departure was 14:10, used on 129 of 277 flights, with 14:06 (41 flights) and 14:05 (34 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 14:10129 flights46.6%
Departs 14:0641 flights14.8%
Departs 14:0534 flights12.3%

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 14:10 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 72.4%, and UA 597 runs level with that at 71.3%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

Against the route

UA 597 next to DEN to BOS

Every carrier on DEN to BOS combined arrived on time 71.4% of the time across 3,903 flights, so UA 597 is about level with it. United flew 1,911 flights on the same city pair under all its flight numbers, including this one, and those ran 77.1% on time. Across its whole network United Airlines managed 79.0%, which this flight trails by 8 points.

UA 597 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
UA 597thin sample	277	71.3%	77 min	1.44%	C
All United Airlines on DEN–BOS	1,911	77.1%	70 min	0.84%	B+
All carriers on DEN–BOS	3,903	71.4%	70 min	1.18%	C
United Airlines, whole network	821,041	79.0%	72 min	1.01%	B

Across the year

UA 597 quarter by quarter

Quarter by quarter UA 597 held fairly steady: 69.2% in Oct–Dec 2025, 73.8% in Jan–Mar 2026 and 73.6% in Apr–Jun 2026. A spread of 5 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Jul–Sep 20256 flights—
Oct–Dec 202591 flights69.2%
Jan–Mar 202689 flights73.8%
Apr–Jun 202691 flights73.6%

Scale runs 60% to 80%. Rows with fewer than 30 flights show a dash.

By weekday, UA 597 did best on Saturday at 82.5% on time and worst on Monday at 60.5%. Each day rests on about 40 flights, so a gap of 22 points is worth noticing but could still narrow in another year.

Delay causes

Why UA 597 runs late

One category carries most of the weight here. National Airspace System accounts for 61% of the 6,018 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.

National Airspace System
61%
Late-arriving aircraft
30%
Carrier
7%
Extreme weather
2%

61% 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 3,680 minutes out of 6,018, against a national NAS share of 21%. The split is drawn from 6,018 delay minutes reported on UA 597.

Cancellations sit at 1.44% against a national 1.81%, which is ordinary. Diversions add another 0.36%.

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. 12.9% 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 eight other city pairs in the data, including PHX to DEN (234), DEN to EWR (37) and CLE to EWR (31), but none flew often enough under UA 597 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to DEN to BOS only.

One caution: this is a thin sample. 277 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 597

For a booking, UA 597 is a flight to put a long connection behind. 12.9% of its completed flights arrived an hour or more late, which a short layover will not absorb. If the onward flight is on a separate ticket, the risk sits with you.

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