Flight number record
F9 3512
Frontier Airlines · Atlanta to Boston
- Route
- ATL → BOS
- Departs
- 05:05
- Flights
- 255
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s F9 3512, check with Frontier Airlines.
F9 3512 sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.3%. The late ones land roughly 55 minutes behind schedule. That rests on 255 flights, with a median arrival 6 minutes early.
The national on-time rate over the same period is 77.3%, so F9 3512 runs 4 points behind the country as a whole. Across a thousand flights that is about 42 extra late arrivals.
Key figures
On time
73.1%
Arrivals under 15 minutes late, of 249 completed flights
Avg delay
53 min
Across delayed arrivals only, not all flights
Cancelled
2.35%
National rate is 1.89%
1 hour+ late
7.6%
National rate is 8.3%
These figures cover 255 flights between September 2025 and August 2026. The median arrival is 6 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
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Schedule
When F9 3512 flies
F9 3512 flies ATL to BOS without a single fixed slot. Its most common scheduled departure was 05:05, used on 65 of 255 flights, with 09:00 (33 flights) next.
- Departs 05:0565 flights25.5%
- Departs 09:0033 flights12.9%
Scale runs 0% to 100%.
Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.
A 05:05 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and F9 3512 runs 16 points worse at 73.1%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
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Against the route
F9 3512 next to ATL to BOS
Every carrier on ATL to BOS combined arrived on time 72.8% of the time across 5,054 flights, so F9 3512 is about level with it. Frontier flew 453 flights on the same city pair under all its flight numbers, including this one, and those ran 67.3% on time. Across its whole network Frontier Airlines managed 72.7%, close to this flight's figure.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| F9 3512thin sample | 255 | 73.1% | 53 min | 2.35% | C |
| All Frontier Airlines on ATL–BOS | 453 | 67.3% | 54 min | 2.87% | C |
| All carriers on ATL–BOS | 5,054 | 72.8% | 66 min | 2.30% | C |
| Frontier Airlines, whole network | 213,022 | 72.7% | 84 min | 2.05% | C |
Across the year
F9 3512 quarter by quarter
F9 3512 did not run the same all year. Its best quarter was Apr–Jun 2026 at 80.0% on time and its weakest Jan–Mar 2026 at 53.1%, a swing of 27 points on roughly 64 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.
- Jul–Sep 202521 flights—
- Oct–Dec 202554 flights71.7%
- Jan–Mar 202633 flights53.1%
- Apr–Jun 202691 flights80.0%
- Jul–Sep 202656 flights71.7%
Scale runs 45% to 85%. Rows with fewer than 30 flights show a dash.
By weekday, F9 3512 did best on Friday at 85.4% on time and worst on Monday at 62.8%. Each day rests on about 36 flights, so a gap of 23 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late F9 3512 runs when it is late
F9 3512 often beats the schedule: 74 of 249 completed flights, 30%, arrived 15 minutes or more early. The 67 late arrivals split 24 under half an hour, 24 between 30 and 60 minutes, and 19 an hour or more.
- 15+ min early74 flights29.7%
- Within 15 min108 flights43.4%
- 15–29 min late24 flights9.6%
- 30–59 min late24 flights9.6%
- 1–2 hours late13 flights5.2%
- 2+ hours late6 flights2.4%
Scale runs 0% to 100%.
Share of 249 completed flights by arrival against schedule.
16 of 68 late departures made up the time and arrived on time, 24% of them. In the other direction, 15 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at BOS.
The worst days
Worst days for F9 3512
The latest arrival of the period was on 4 January 2026, 4 hours 16 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on four of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 4 January 2026 | 4 hours 16 minutes | Late-arriving aircraft |
| 7 June 2026 | 3 hours 27 minutes | Carrier |
| 16 March 2026 | 2 hours 30 minutes | Late-arriving aircraft |
| 8 November 2025 | 2 hours 17 minutes | Late-arriving aircraft |
| 18 July 2026 | 2 hours 11 minutes | Late-arriving aircraft |
Delay causes
Why F9 3512 runs late
Carrier accounts for 56% of the 3,552 delay minutes carriers reported here, and the remaining four split what is left.
- 56%Carrier
- 28%Late-arriving aircraft
- 17%National Airspace System
The largest share of delay minutes, 56%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,973 of the 3,552 delay minutes reported here. The split is drawn from 3,552 delay minutes reported on F9 3512.
Cancellations sit at 2.35% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
7.6% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last roughly 55 minutes, which a normal layover absorbs.
The 946 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.
Every one of the 255 flights under F9 3512 in the data flew ATL to BOS. 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. 255 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 3512
For a booking, read F9 3512 as 73.1% on time with 2.35% cancelled over 255 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- ATL to BOS, every carrier and departure
- BOS to ATL, the return direction
- Delta Air Lines 855 on the same route85.2%
- Delta Air Lines 865 on the same route80.2%
- Delta Air Lines 726 on the same route66.3%
- Delta Air Lines 821 on the same route69.2%
- Delta Air Lines 987 on the same route89.9%
- Delta Air Lines 350 on the same route74.6%
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Boston Logan International (BOS) 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
- The best time of day to fly, according to 7.05 million flight records
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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.