Flight number record
F9 2551
Frontier Airlines · Philadelphia to Atlanta
- Route
- PHL → ATL
- Departs
- 05:30
- Flights
- 293
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s F9 2551, check with Frontier Airlines.
F9 2551 sits in the middle of the pack with a C−. About seven flights in ten arrive on time by the DOT's definition, 7 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 293 flights, with a median arrival 5 minutes early.
The national on-time rate over the same period is 77.6%, so F9 2551 runs 7 points behind the country as a whole. Across a thousand flights that is about 70 extra late arrivals.
Key figures
On time
70.6%
Arrivals under 15 minutes late, of 279 completed flights
Avg delay
64 min
Across delayed arrivals only, not all flights
Cancelled
4.44%
National rate is 1.81%
1 hour+ late
8.2%
National rate is 8.1%
These figures cover 293 flights between July 2025 and June 2026. Beyond the headline rate, 8.2% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Schedule
When F9 2551 flies
F9 2551 flies PHL to ATL without a single fixed slot. Its most common scheduled departure was 05:30, used on 79 of 293 flights, with 06:30 (48 flights) and 05:05 (34 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 05:3079 flights27.0%
- Departs 06:3048 flights16.4%
- Departs 05:0534 flights11.6%
Scale runs 0% to 100%. Rows with fewer than 30 flights show a dash.
Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.
A 05:30 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and F9 2551 runs 19 points worse at 70.6%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
Against the route
F9 2551 next to PHL to ATL
Every carrier on PHL to ATL combined arrived on time 79.2% of the time across 5,713 flights, so F9 2551 is 9 points behind it. Frontier flew 1,008 flights on the same city pair under all its flight numbers, including this one, and those ran 66.4% on time. Across its whole network Frontier Airlines managed 73.2%, which this flight trails by 3 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| F9 2551thin sample | 293 | 70.6% | 64 min | 4.44% | C− |
| All Frontier Airlines on PHL–ATL | 1,008 | 66.4% | 71 min | 2.78% | C |
| All carriers on PHL–ATL | 5,713 | 79.2% | 66 min | 2.73% | B |
| Frontier Airlines, whole network | 205,332 | 73.2% | 84 min | 1.85% | C |
Across the year
F9 2551 quarter by quarter
Quarter by quarter F9 2551 held fairly steady: 75.0% in Jul–Sep 2025, 72.1% in Oct–Dec 2025, 65.8% in Jan–Mar 2026 and 70.7% in Apr–Jun 2026. A spread of 9 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.
- Jul–Sep 202558 flights75.0%
- Oct–Dec 202575 flights72.1%
- Jan–Mar 202676 flights65.8%
- Apr–Jun 202684 flights70.7%
Scale runs 55% to 80%. Rows with fewer than 30 flights show a dash.
By weekday, F9 2551 ranged from 65.2% on Monday to 73.9% on Thursday. With about 42 flights behind each day, a spread of 9 points is inside normal variation, so the day you fly is not worth changing for this flight.
Delay causes
Why F9 2551 runs late
One category carries most of the weight here. National Airspace System accounts for 44% of the 5,255 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 44%National Airspace System
- 33%Carrier
- 21%Late-arriving aircraft
- 2%Extreme weather
44% 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 2,300 minutes out of 5,255, against a national NAS share of 21%. The split is drawn from 5,255 delay minutes reported on F9 2551.
Cancellations run at 4.44%, against 1.81% nationally. That is roughly one flight in 25 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.
Connections and routes
What a delay on this flight costs
8.2% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
The 666 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. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
Every one of the 293 flights under F9 2551 in the data flew PHL to ATL. The number was not reused on any other city pair, which makes this a clean record of one route.
One caution: this is a thin sample. 293 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 F9 2551
For a booking, the cancellation rate is the figure to plan around on F9 2551: 4.44% of its 293 scheduled flights did not operate. A late arrival costs about an hour, but a cancellation costs the day, so leave a later option open.
Related
Where to go next
- PHL to ATL, every carrier and departure
- ATL to PHL, the return direction
- Delta Air Lines 1152 on the same route89.9%
- Delta Air Lines 2270 on the same route88.2%
- Delta Air Lines 1180 on the same route88.0%
- Delta Air Lines 1269 on the same route91.4%
- Delta Air Lines 1169 on the same route75.4%
- Delta Air Lines 1100 on the same route87.6%
- Philadelphia International (PHL) delay statistics
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Frontier Airlines on-time record
- Every Frontier Airlines flight number with a record
- The most and least reliable flight numbers in the US
- What a cancellation rate actually tells you (and what it hides)
A flight number here means Frontier 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.