Flight number record
UA 597
United Airlines · Denver to Boston
- Route
- DEN → BOS
- Departs
- 14:10
- Flights
- 339
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 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, 9 points worse than the national rate of 77.3%. The late ones land an hour and a half behind schedule. That rests on 339 flights, with a median arrival 6 minutes early.
The national on-time rate over the same period is 77.3%, so UA 597 runs 9 points behind the country as a whole. Across a thousand flights that is about 88 extra late arrivals.
Key figures
On time
68.5%
Arrivals under 15 minutes late, of 333 completed flights
Avg delay
86 min
Across delayed arrivals only, not all flights
Cancelled
1.18%
National rate is 1.89%
1 hour+ late
15.3%
National rate is 8.3%
These figures cover 339 flights between September 2025 and August 2026. Beyond the headline rate, 15.3% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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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 339 flights, with 14:06 (82 flights) and 14:05 (34 flights) next.
- Departs 14:10129 flights38.1%
- Departs 14:0682 flights24.2%
- Departs 14:0534 flights10.0%
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 14:10 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 71.9%, and UA 597 runs 3 points worse at 68.5%. 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 597 next to DEN to BOS
Every carrier on DEN to BOS combined arrived on time 69.6% of the time across 3,851 flights, so UA 597 is about level with it. United flew 1,887 flights on the same city pair under all its flight numbers, including this one, and those ran 76.8% on time. Across its whole network United Airlines managed 78.8%, which this flight trails by 10 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 597thin sample | 339 | 68.5% | 86 min | 1.18% | C |
| All United Airlines on DEN–BOS | 1,887 | 76.8% | 75 min | 0.95% | B+ |
| All carriers on DEN–BOS | 3,851 | 69.6% | 73 min | 1.45% | C |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | B |
Across the year
UA 597 quarter by quarter
UA 597 did not run the same all year. Its best quarter was Jan–Mar 2026 at 73.8% on time and its weakest Jul–Sep 2026 at 55.7%, a swing of 18 points on roughly 85 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 20256 flights—
- Oct–Dec 202591 flights69.2%
- Jan–Mar 202689 flights73.8%
- Apr–Jun 202691 flights73.6%
- Jul–Sep 202662 flights55.7%
Scale runs 45% to 80%. Rows with fewer than 30 flights show a dash.
By weekday, UA 597 did best on Tuesday at 76.6% on time and worst on Monday at 54.3%. Each day rests on about 48 flights, so a gap of 22 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late UA 597 runs when it is late
UA 597 often beats the schedule: 105 of 333 completed flights, 32%, arrived 15 minutes or more early. The 105 late arrivals split 28 under half an hour, 26 between 30 and 60 minutes, and 51 an hour or more.
- 15+ min early105 flights31.5%
- Within 15 min123 flights36.9%
- 15–29 min late28 flights8.4%
- 30–59 min late26 flights7.8%
- 1–2 hours late25 flights7.5%
- 2+ hours late26 flights7.8%
Scale runs 0% to 100%.
Share of 333 completed flights by arrival against schedule.
17 of 108 late departures made up the time and arrived on time, 16% of them. 14 flights left on time and still arrived late.
The worst days
Worst days for UA 597
The latest arrival of the period was on 30 October 2025, 5 hours 56 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. Three of the five worst days fell in October 2025.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 30 October 2025 | 5 hours 56 minutes | Late-arriving aircraft |
| 6 July 2026 | 5 hours 41 minutes | Carrier |
| 25 September 2025 | 5 hours 27 minutes | National Airspace System |
| 14 October 2025 | 4 hours 53 minutes | National Airspace System |
| 13 October 2025 | 4 hours 24 minutes | Late-arriving aircraft |
Delay causes
Why UA 597 runs late
National Airspace System accounts for 60% of the 8,992 delay minutes carriers reported here, and the remaining four split what is left.
- 60%National Airspace System
- 26%Late-arriving aircraft
- 12%Carrier
- 1%Extreme weather
60% 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 5,428 minutes out of 8,992, against a national NAS share of 21%. The split is drawn from 8,992 delay minutes reported on UA 597.
Cancellations sit at 1.18% against a national 1.89%, which is ordinary. Diversions add another 0.59%.
Connections and routes
What a delay on this flight costs
15.3% 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.
UA 597 is not only a DEN to BOS flight. It also flew PHX to DEN (262 flights, 86.2% on time) often enough to be scored on its own. Airlines attach one number to several legs of an aircraft's day, and each leg keeps its own record here, so check which city pair is on your booking before reading a rate.
One caution: this is a thin sample. 339 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.
| Also flown as | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| PHX to DENthin sample | 262 | 86.2% | 70 min | 0.38% | A+ |
What to do with this
Booking UA 597
For a booking, UA 597 is a flight to put a long connection behind. 15.3% 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.
Related
Where to go next
- DEN to BOS, every carrier and departure
- BOS to DEN, the return direction
- Delta Air Lines 499 on the same route71.5%
- United Airlines 558 on the same route91.9%
- JetBlue Airways 394 on the same route61.8%
- JetBlue Airways 994 on the same route67.2%
- Denver International (DEN) delay statistics
- Boston Logan International (BOS) 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
- How often a connection fails at the major US hubs
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.