Flight profile · Frontier Airlines
F91230
San Francisco (SFO) to Denver (DEN) · scheduled 6:00 AM – 9:46 AM
How F91230 performs
765 operations, November 2023 – July 2026.
F91230 arrived on time 83.4% of the time, against 76.4% for all SFO → DEN flights, so this departure is 7.0 percentage points better than the route as a whole. Against Frontier Airlines’ own flights on this route it is 15.1 points better.
F91230’s scheduled departure has moved during the period FlyerIntel has on file: it typically left around 6:00 AM earlier on, and around 6:30 AM more recently — a 30-minute shift, not the few minutes of day-to-day rounding every published schedule carries. Confirm the current departure time before booking around an older listing.
Source: US DOT Bureau of Transportation Statistics · 765 operations, November 2023 – July 2026 · If F91230 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 F91230 compares to other flight numbers, not just to itself.
This flight runs unusually far ahead of the carrier's own average on this route, better than 98% of 11,589 comparable flight numbers.
83.4% on time for this specific departure, against 68.3% for the same carrier's other flights on this route.
Source: FlyerIntel analysis of US DOT BTS data · November 2023 – 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 F91230 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 |
|---|---|---|---|---|---|
| F91230 | 83.4% | 0.78% | -8 min | 5.7% | 765 |
| Frontier Airlines on SFO → DEN | 68.3% | 1.10% | -1 min | 12.8% | 2,009 |
| All SFO → DEN flights | 76.4% | 0.62% | -5 min | 7.9% | 17,119 |
Source: FlyerIntel analysis of US DOT BTS data · November 2023 – July 2026
Why F91230 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 F91230 on SFO → DEN. 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 F91230 comes in late, and what that does to the departure.
When the aircraft came in 15 or more minutes late, F91230 pushed back an average of 13 minutes late; when it came in on time or early, an average of 3 minutes late.
Each departure is matched to the flight the same aircraft flew into SFO just before it, using the tail number in the DOT file, 748 of 759 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 |
|---|---|---|---|
| F91230 | 31% | 20% | 9% |
| Network, same turn | 33% | 24% | 11% |
The schedule leaves a long gap on the ground, which gives a late aircraft room to catch up before this flight pushes back.
The network row is every flight with a scheduled turn of 3 to 6 hours. How often F91230’s aircraft landed 15 or more minutes late is about the same as the network’s and, once the aircraft was late, how often F91230 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 SFO late, does that still matter by the time it reaches DEN?
F91230 pushes back an average of 8.4 minutes late and reaches the gate at DEN an average of 4.2 minutes late. The 4.2 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. Its 17.9 minutes on the taxiways at SFO is about what any departure from the airport in that hour spends.
On arrival at DEN, F91230 spends 17.3 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 7.5 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 20,979 departures from SFO scheduled in the clock hour F91230 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 F91230’s own. More on taxi time.
Source: FlyerIntel analysis of US DOT BTS data · November 2023 – July 2026
The hour it leaves SFO
Part of any flight’s record belongs to the clock rather than to the flight. F91230 has one departure time, so this is what that time is worth.
On-time arrival rate. 20,979 departures from SFO are scheduled in the 6 AM–7 AM hour over the period, against 435,779 across the whole day.
F91230 is scheduled out of SFO at 6:00 AM, in the 6 AM–7 AM bank. Departures from SFO in that hour arrive on time 92.3% of the time against 78.7% across the airport’s whole day — the slot alone is worth 13.6 points better before anything about this particular flight is considered.
The two airport figures cover every departure from SFO 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.
When it goes wrong
The average describes a usual day. This is the day that ruins a connection.
32 min late
against a median of 8 min early
Percentiles over 765 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 |
|---|---|---|---|---|
| F91230 this flight | Frontier Airlines | 83.4% | 8 min early | 765 |
| UA566 | United Airlines | 77.3% | 4 min early | 705 |
Every departure listed carries at least 600 operations, so the comparison is between figures that mean something. F91230 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 765 records of F91230 operating SFO → 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
Analysis last recomputed