Flight number record
UA 1023
United Airlines · Denver to Chicago
- Route
- DEN → ORD
- Departs
- 15:20
- Flights
- 364
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s UA 1023, check with United Airlines.
UA 1023 draws a D+. Roughly one flight in two arrives at least 15 minutes late, and the typical late arrival is a little over an hour behind schedule. Build slack into anything you connect to. That rests on 364 flights, with a median arrival 7 minutes late.
The national on-time rate over the same period is 77.3%, so UA 1023 runs 18 points behind the country as a whole. Across a thousand flights that is about 175 extra late arrivals.
Key figures
On time
59.8%
Arrivals under 15 minutes late, of 361 completed flights
Avg delay
70 min
Across delayed arrivals only, not all flights
Cancelled
0.27%
National rate is 1.89%
1 hour+ late
10.8%
National rate is 8.3%
These figures cover 364 flights between September 2025 and August 2026. Beyond the headline rate, 10.8% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When UA 1023 flies
UA 1023 flies DEN to ORD without a single fixed slot. Its most common scheduled departure was 15:20, used on 74 of 364 flights, with 14:45 (55 flights) and 15:01 (47 flights) next.
- Departs 15:2074 flights20.3%
- Departs 14:4555 flights15.1%
- Departs 15:0147 flights12.9%
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 15:20 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 71.9%, and UA 1023 runs 12 points worse at 59.8%. 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 1023 next to DEN to ORD
Every carrier on DEN to ORD combined arrived on time 71.8% of the time across 6,109 flights, so UA 1023 is 12 points behind it. United flew 3,885 flights on the same city pair under all its flight numbers, including this one, and those ran 71.9% on time. Across its whole network United Airlines managed 78.8%, which this flight trails by 19 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 1023thin sample | 364 | 59.8% | 70 min | 0.27% | D+ |
| All United Airlines on DEN–ORD | 3,885 | 71.9% | 82 min | 0.82% | C+ |
| All carriers on DEN–ORD | 6,109 | 71.8% | 88 min | 1.11% | C |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | B |
Across the year
UA 1023 quarter by quarter
UA 1023 did not run the same all year. Its best quarter was Apr–Jun 2026 at 73.0% on time and its weakest Oct–Dec 2025 at 50.5%, a swing of 23 points on roughly 73 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 202530 flights70.0%
- Oct–Dec 202591 flights50.5%
- Jan–Mar 202690 flights55.1%
- Apr–Jun 202691 flights73.0%
- Jul–Sep 202662 flights56.5%
Scale runs 40% to 80%.
By weekday, UA 1023 did best on Tuesday at 71.2% on time and worst on Thursday at 48.0%. Each day rests on about 52 flights, so a gap of 23 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late UA 1023 runs when it is late
The 145 late arrivals split 61 under half an hour, 45 between 30 and 60 minutes, and 39 an hour or more.
- 15+ min early38 flights10.5%
- Within 15 min178 flights49.3%
- 15–29 min late61 flights16.9%
- 30–59 min late45 flights12.5%
- 1–2 hours late18 flights5.0%
- 2+ hours late21 flights5.8%
Scale runs 0% to 100%.
Share of 361 completed flights by arrival against schedule.
Time lost at the gate mostly stays lost. Of 74 departures that left 15 minutes late or more, only 8 made it up before arrival. In the other direction, 79 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 ORD.
The worst days
Worst days for UA 1023
The latest arrival of the period was on 3 July 2026, 10 hours 26 minutes behind schedule; most of its delay minutes were filed as national airspace system delay. The same cause led on four of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 3 July 2026 | 10 hours 26 minutes | National Airspace System |
| 27 April 2026 | 8 hours 19 minutes | National Airspace System |
| 10 March 2026 | 7 hours 57 minutes | Extreme weather |
| 27 July 2026 | 6 hours 4 minutes | National Airspace System |
| 10 June 2026 | 6 hours 1 minute | National Airspace System |
Delay causes
Why UA 1023 runs late
National Airspace System accounts for 71% of the 10,000 delay minutes carriers reported here, and the remaining four split what is left.
- 71%National Airspace System
- 16%Late-arriving aircraft
- 8%Carrier
- 5%Extreme weather
71% 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 7,172 minutes out of 10,000, against a national NAS share of 21%. The split is drawn from 10,093 delay minutes reported on UA 1023.
Cancellations are rare at 0.27%, below the national 1.89% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and routes
What a delay on this flight costs
10.8% 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.
The 888 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.
The same number turns up on seven other city pairs in the data, including SMF to DEN (103), ORD to IAD (55) and AUS to DEN (31), but none flew often enough under UA 1023 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to DEN to ORD 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 1023
For a booking, UA 1023 is one of the weaker ways to fly DEN to ORD: 12 points below the route as a whole. If the schedule allows, compare it with the other departures listed on the route page before settling on this one.
Related
Where to go next
- DEN to ORD, every carrier and departure
- ORD to DEN, the return direction
- United Airlines 2865 on the same route79.2%
- United Airlines 2329 on the same route84.1%
- United Airlines 617 on the same route68.8%
- United Airlines 1377 on the same route90.0%
- American Airlines 2771 on the same route87.9%
- United Airlines 2258 on the same route71.2%
- Denver International (DEN) delay statistics
- Chicago O'Hare International (ORD) 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.