Flight profile · United Airlines
UA2123
Kansas City (MCI) to Denver (DEN) · scheduled 5:15 PM – 6:25 PM
How UA2123 performs
782 operations, March 2024 – July 2026.
UA2123 arrived on time 65.0% of the time, against 78.2% for all MCI → DEN flights, so this departure is 13.2 percentage points worse than the route as a whole. Against United Airlines’ own flights on this route it is 16.2 points worse.
Source: US DOT Bureau of Transportation Statistics · 782 operations, March 2024 – July 2026 · If UA2123 is cancelled or significantly changed, DOT’s automatic refund rule may entitle you to your money back. The refund checker walks through eligibility.
What stands out
How UA2123 compares to other flight numbers, not just to itself.
This flight runs unusually far behind the carrier's own average on this route, worse than 96% of 11,589 comparable flight numbers.
65.0% on time for this specific departure, against 81.2% for the same carrier's other flights on this route.
Source: FlyerIntel analysis of US DOT BTS data · March 2024 – July 2026 · The one thing about this specific departure that ranks most extreme against every other published flight number, out of everything FlyerIntel checks — shown only when something clears a real statistical bar, not for every flight.
Where UA2123 is right now
A live reading, only if you ask for it. It is not part of the reliability record above.
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Against the rest of the route
| Flight or route | On time | Cancelled | Median delay | Severe | Flights |
|---|---|---|---|---|---|
| UA2123 | 65.0% | 1.02% | 5 min | 14.5% | 782 |
| United Airlines on MCI → DEN | 81.2% | 0.76% | -5 min | 6.0% | 4,322 |
| All MCI → DEN flights | 78.2% | 0.89% | -3 min | 7.3% | 13,213 |
Source: FlyerIntel analysis of US DOT BTS data · March 2024 – July 2026
Why UA2123 runs late
Where US DOT attributed the delay minutes on this flight.
airspace and airport capacity, including weather-driven flow control
the inbound aircraft was late, so this flight started late
crew, maintenance, boarding and fueling, all within the carrier’s control
weather severe enough to stop this flight specifically
Share of the delay minutes US DOT attributed to each cause for UA2123 on MCI → DEN. Only delays of 15 minutes or more are attributed.
Source: US DOT Bureau of Transportation Statistics · Data covering March 2024 – July 2026
Does a late aircraft delay this flight?
How often the plane that flies UA2123 comes in late, and what that does to the departure.
When the aircraft came in 15 or more minutes late, UA2123 pushed back an average of 56 minutes late; when it came in on time or early, an average of 9 minutes late.
Each departure is matched to the flight the same aircraft flew into MCI just before it, using the tail number in the DOT file, 764 of 774 departures in all. A departure is left out when that flight is unknown, was cancelled or diverted, or the aircraft had sat for more than 12 hours. A flight the airline cancelled never left and is not in the count, and one flown by a substitute aircraft is matched to the aircraft that flew it, not to the one first planned.
Against the network at the same turn length
| Share of departures | Inbound landed 15+ late | Left 15+ late after a late inbound | Left 15+ late after an on-time inbound |
|---|---|---|---|
| UA2123 | 16% | 68% | 16% |
| Network, same turn | 17% | 68% | 9% |
The schedule leaves a normal turn: enough time to clean and board if the aircraft is on time, little to spare if it is not.
The network row is every flight with a scheduled turn of 60 to 89 minutes. How often UA2123’s aircraft landed 15 or more minutes late is about the same as the network’s and, once the aircraft was late, how often UA2123 left 15 or more minutes late is about the same as the network’s.
More: Which Flight Numbers Pay for a Late Aircraft lists the flight numbers that pass a late aircraft on.
Source: US DOT Bureau of Transportation Statistics · Data covering March 2024 – July 2026
From pushback to gate
When it leaves MCI late, does that still matter by the time it reaches DEN?
UA2123 pushes back an average of 18.2 minutes late and arrives a further 5.4 minutes behind that. This departure loses ground between the two gates rather than recovering it, so a late pushback here tends to get worse on the way, not better. It spends 25.9 minutes on the taxiways at MCI, 10.8 minutes longer than a typical MCI departure in the same hour.
On arrival at DEN, UA2123 spends 11.1 min taxiing from touchdown to the gate — ground time a connecting passenger sits through before they can even leave the aircraft, on top of however late the flight itself ran. That is 1.3 minutes longer than a typical DEN arrival (9.8 min).
Departure delay is averaged over every pushback and arrival delay over every completed arrival, so the two counts differ by the flights that never reached DEN. Taxi-out is gate to wheels up and sits inside the scheduled block rather than on top of it; the comparison is 12,459 departures from MCI scheduled in the clock hour UA2123 most often leaves in. Taxi-in is landing to gate, compared against every arrival FlyerIntel has on file at DEN (963,027 flights), not just UA2123’s own. More on taxi time.
Source: FlyerIntel analysis of US DOT BTS data · March 2024 – July 2026
The hour it leaves MCI
Part of any flight’s record belongs to the clock rather than to the flight. UA2123 has one departure time, so this is what that time is worth.
On-time arrival rate. 12,459 departures from MCI are scheduled in the 5 PM–6 PM hour over the period, against 152,682 across the whole day.
UA2123 is scheduled out of MCI at 5:15 PM, in the 5 PM–6 PM bank. Departures from MCI in that hour arrive on time 71.1% of the time against 81.0% across the airport’s whole day — the slot alone is worth 9.9 points worse before anything about this particular flight is considered.
The two airport figures cover every departure from MCI to every destination, so they describe the slot rather than this journey — the like-for-like comparison against the route is above. Hours are scheduled local, and a number whose schedule moved between banks inside the period has no single hour and is not described here at all. Why the hour matters.
Source: FlyerIntel analysis of US DOT BTS data · March 2024 – July 2026 · Hours below 120 departures are not scored.
Other routes UA2123 has flown
A flight number is a slot in a schedule, and carriers reassign it. These are the other city pairs this number served in the analysis period.
| Route | Operated | Flights | On time |
|---|---|---|---|
| DEN→SFO Denver to San Francisco | October 26, 2025 – July 31, 2026 | 275 | 57.7% |
| SJC→DEN San Jose to Denver | February 12, 2026 – March 4, 2026 | 21 | — |
| MFR→SFO Medford to San Francisco | February 15, 2024 – March 6, 2024 | 21 | — |
| AUS→SFO Austin to San Francisco | July 1, 2023 – February 14, 2024 | 229 | 90.8% |
| SFO→JAC San Francisco to Jackson | January 9, 2024 – February 13, 2024 | 34 | — |
| SFO→LAX San Francisco to Los Angeles | September 5–28, 2023 | 24 | — |
| SFO→SAN San Francisco to San Diego | July 1, 2023 – September 4, 2023 | 66 | — |
Because the same number has served different journeys, the statistics above describe only the route UA2123 currently operates. Blending them would produce an average of two different flights.
When it goes wrong
The average describes a usual day. This is the day that ruins a connection.
88 min late
against a median of 5 min late
UA2123 has an average that understates its risk: a typical arrival is 5 min late, but the worst tenth are 83 minutes worse than that. If the trip has something unmissable at the end of it, the median is the wrong number to plan against.
Percentiles over 782 operations; cancelled and diverted flights are counted separately.
Source: US DOT Bureau of Transportation Statistics · Data covering March 2024 – July 2026
Other flights on this route
Same airports, same journey, different odds of arriving on time.
| Flight | Airline | On time | Median arrival | Operations |
|---|---|---|---|---|
| UA2391 | United Airlines | 94.1% | 11 min early | 720 |
| UA708 | United Airlines | 88.5% | 11 min early | 947 |
| UA2123 this flight | United Airlines | 65.0% | 5 min late | 782 |
Every departure listed carries at least 600 operations, so the comparison is between figures that mean something. UA2123 is placed in the same ordering rather than left out of it; the rows around it are the most punctual departures on the route, not all of them, so this is a comparison and not a rank. Schedules change; confirm the departure still operates before booking around this.
Data and methodology
Calculated by FlyerIntel from 782 records of UA2123 operating MCI → DEN, published by the US DOT Bureau of Transportation Statistics. A flight counts as delayed when it arrives 15 or more minutes after schedule. Cancelled and diverted flights are excluded from the on-time rate and reported separately. Flight numbers are resolved as carrier plus number plus route, because the same number serves different routes over time.
Full methodology · Data sources · Report a problem
Related research: Most and Least Reliable Flight Numbers · The Delay You Inherit · Making Up Time in the Air
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