Flight profile · Frontier Airlines
F91204
Miami (MIA) to Philadelphia (PHL) · scheduled 5:30 AM – 12:27 AM
How F91204 performs
621 operations, January 2024 – August 2026.
Between its first and last recorded date on MIA → PHL, F91204 averaged about 5 operations a week (621 in 964 days, cancelled ones included).
F91204 arrived on time 76.1% of the time, against 74.1% for all MIA → PHL flights, so this departure is 2.0 percentage points better than the route as a whole. Against Frontier Airlines’ own flights on this route it is 3.6 points better.
Source: US DOT Bureau of Transportation Statistics · 621 operations, January 2024 – August 2026 · If F91204 is cancelled or significantly changed, DOT’s automatic refund rule may entitle you to your money back. The refund checker walks through eligibility.
Where F91204 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 |
|---|---|---|---|---|---|
| F91204 | 76.1% | 2.42% | -10 min | 11.2% | 621 |
| Frontier Airlines on MIA → PHL | 72.5% | 2.23% | -6 min | 13.4% | 1,257 |
| All MIA → PHL flights | 74.1% | 2.18% | -5 min | 10.6% | 10,191 |
F91204 cancelled 15 of 621 operations (2.42%), close to the 2.18% for MIA → PHL.
Source: FlyerIntel analysis of US DOT BTS data · January 2024 – August 2026
Why F91204 runs late
Where US DOT attributed the delay minutes on this flight.
the inbound aircraft was late, so this flight started late
crew, maintenance, boarding and fueling, all within the carrier’s control
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 F91204 on MIA → PHL. Only delays of 15 minutes or more are attributed. What the five causes mean
Source: US DOT Bureau of Transportation Statistics · Data covering January 2024 – August 2026
Does a late aircraft delay this flight?
How often the plane that flies F91204 comes in late, and what that does to the departure.
When the aircraft came in 15 or more minutes late, F91204 pushed back an average of 48 minutes late; when it came in on time or early, an average of 0 minutes late.
Matched by tail number to the aircraft’s previous flight into MIA: 522 of 607 departures. Unknown, cancelled or diverted inbounds and gaps over 12 hours are left out.
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 |
|---|---|---|---|
| F91204 | 36% | 60% | 10% |
| Network, same turn | 17% | 69% | 9% |
70 scheduled minutes is enough to clean and board when the aircraft is on time, with little to spare when it is not.
The network row is every flight with a scheduled turn of 60 to 89 minutes. How often F91204’s aircraft landed 15 or more minutes late is higher than the network’s and, once the aircraft was late, how often F91204 left 15 or more minutes late is lower than the network’s.
Source: US DOT Bureau of Transportation Statistics · Data covering January 2024 – August 2026
From pushback to gate
When it leaves MIA late, does that still matter by the time it reaches PHL?
F91204 pushes back an average of 23.9 minutes late and reaches the gate at PHL an average of 14.1 minutes late. The 9.8 minutes between those two figures are slack the published schedule already carries, so a late pushback is partly, not fully, made up before the gate. It spends 20.7 minutes on the taxiways at MIA, 5.3 minutes longer than a typical MIA departure in the same hour.
On arrival at PHL, F91204 spends 12.3 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 4.2 minutes longer than a typical PHL arrival (8.2 min).
Taxi-out is gate to wheels up and sits inside the scheduled block; the hourly comparison is 4,031 MIA departures. Taxi-in is landing to gate, set against 315,181 arrivals at PHL. More on taxi time.
Source: FlyerIntel analysis of US DOT BTS data · January 2024 – August 2026
The hour it leaves MIA
F91204 has one departure time, 5:30 AM, so this is what that hour at MIA is worth.
On-time arrival rate. 4,031 departures from MIA are scheduled in the 5 AM–6 AM hour over the period, against 349,146 across the whole day.
F91204 is scheduled out of MIA at 5:30 AM, in the 5 AM–6 AM bank. Departures from MIA in that hour arrive on time 89.8% of the time against 73.2% across the airport’s whole day — the slot alone is worth 16.6 points better before anything about this particular flight is considered.
Both airport figures cover every destination from MIA, so they describe the slot, not this journey; the route comparison is above. Why the hour matters.
Source: FlyerIntel analysis of US DOT BTS data · January 2024 – August 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.
71 min late
against a median of 10 min early
F91204 has an average that understates its risk: a typical arrival is 10 min early, but the worst tenth are 81 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 621 operations; cancelled and diverted flights are counted separately.
Source: US DOT Bureau of Transportation Statistics · Data covering January 2024 – August 2026
Other flights on this route
Same airports, same journey, different odds of arriving on time.
| Flight | Airline | On time | Median arrival | Operations |
|---|---|---|---|---|
| AA551 | American Airlines | 86.0% | 11 min early | 748 |
| F91204 this flight | Frontier Airlines | 76.1% | 10 min early | 621 |
| AA2188 | American Airlines | 70.2% | 3 min early | 635 |
Among all 3 departures on this route with at least 600 operations, F91204 has the 2nd highest on-time rate, 9.9 points behind the best. Every departure here has at least 600 operations; the other rows are the most punctual on the route, not all of them.
Data and methodology
Calculated by FlyerIntel from 621 records of F91204 operating MIA → PHL, 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 reported separately, not in the on-time rate.
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