Flight profile · Frontier Airlines
F91261
Denver (DEN) to Ontario (ONT) · scheduled 10:29 PM – 11:49 PM
How F91261 performs
791 operations, November 2023 – July 2026.
F91261 arrived on time 83.2% of the time, against 74.4% for all DEN → ONT flights, so this departure is 8.8 percentage points better than the route as a whole. Against Frontier Airlines’ own flights on this route it is 5.5 points better.
Source: US DOT Bureau of Transportation Statistics · 791 operations, November 2023 – July 2026 · If F91261 is cancelled or significantly changed, DOT’s automatic refund rule may entitle you to your money back. The refund checker walks through eligibility.
Where F91261 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 |
|---|---|---|---|---|---|
| F91261 | 83.2% | 0.51% | -10 min | 5.8% | 791 |
| Frontier Airlines on DEN → ONT | 77.7% | 0.81% | -7 min | 7.8% | 1,973 |
| All DEN → ONT flights | 74.4% | 0.60% | -3 min | 8.1% | 8,691 |
Source: FlyerIntel analysis of US DOT BTS data · November 2023 – July 2026
Why F91261 runs late
Where US DOT attributed the delay minutes on this flight.
crew, maintenance, boarding and fueling, all within the carrier’s control
the inbound aircraft was late, so this flight started late
airspace and airport capacity, including weather-driven flow control
weather severe enough to stop this flight specifically
Share of the delay minutes US DOT attributed to each cause for F91261 on DEN → ONT. Only delays of 15 minutes or more are attributed.
Source: US DOT Bureau of Transportation Statistics · Data covering November 2023 – July 2026
Does a late aircraft delay this flight?
How often the plane that flies F91261 comes in late, and what that does to the departure.
When the aircraft came in 15 or more minutes late, F91261 pushed back an average of 26 minutes late; when it came in on time or early, an average of 2 minutes late.
Each departure is matched to the flight the same aircraft flew into DEN just before it, using the tail number in the DOT file, 700 of 787 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 |
|---|---|---|---|
| F91261 | 25% | 40% | 12% |
| 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 F91261’s aircraft landed 15 or more minutes late is higher than the network’s and, once the aircraft was late, how often F91261 left 15 or more minutes late is lower than 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 November 2023 – July 2026
From pushback to gate
When it leaves DEN late, does that still matter by the time it reaches ONT?
F91261 pushes back an average of 8.5 minutes late and reaches the gate at ONT an average of 0.4 minutes late. The 8.1 minutes between those two figures are slack the published schedule already carries, which is why a late pushback on this flight does not reliably become a late arrival. It spends 16.9 minutes on the taxiways at DEN, 1.3 minutes longer than a typical DEN departure in the same hour.
On arrival at ONT, F91261 spends 6.7 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 1.4 minutes longer than a typical ONT arrival (5.2 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 ONT. Taxi-out is gate to wheels up and sits inside the scheduled block rather than on top of it; the comparison is 14,120 departures from DEN scheduled in the clock hour F91261 most often leaves in. Taxi-in is landing to gate, compared against every arrival FlyerIntel has on file at ONT (79,947 flights), not just F91261’s own. More on taxi time.
Source: FlyerIntel analysis of US DOT BTS data · November 2023 – July 2026
The hour it leaves DEN
Part of any flight’s record belongs to the clock rather than to the flight. F91261 has one departure time, so this is what that time is worth.
On-time arrival rate. 14,120 departures from DEN are scheduled in the 10 PM–11 PM hour over the period, against 963,099 across the whole day.
F91261 is scheduled out of DEN at 10:29 PM, in the 10 PM–11 PM bank. Departures from DEN in that hour arrive on time 63.6% of the time against 76.0% across the airport’s whole day — the slot alone is worth 12.4 points worse before anything about this particular flight is considered.
The two airport figures cover every departure from DEN 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 · November 2023 – July 2026 · Hours below 120 departures are not scored.
Other routes F91261 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.
Because the same number has served different journeys, the statistics above describe only the route F91261 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.
35 min late
against a median of 10 min early
Percentiles over 791 operations; cancelled and diverted flights are counted separately.
Source: US DOT Bureau of Transportation Statistics · Data covering November 2023 – July 2026
Other flights on this route
Same airports, same journey, different odds of arriving on time.
| Flight | Airline | On time | Median arrival | Operations |
|---|---|---|---|---|
| UA430 | United Airlines | 85.4% | 9 min early | 1,061 |
| F91261 this flight | Frontier Airlines | 83.2% | 10 min early | 791 |
| F91499 | Frontier Airlines | 75.0% | 5 min early | 692 |
Every departure listed carries at least 600 operations, so the comparison is between figures that mean something. F91261 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 791 records of F91261 operating DEN → ONT, 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
Analysis last recomputed