Carrier route record

F9ATL→BOS

Frontier Airlines · Atlanta to Boston

Flights: 400
Period: July 2025 to June 2026
Share of route: 8%
Carriers: 4

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Frontier Airlines.

Frontier on ATL to BOS draws a C. About one flight in three arrives at least 15 minutes late, and the typical late arrival is about an hour behind schedule. Build slack into anything you connect to. That rests on 400 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 3,666 at 76.2% on time.

The national on-time rate over the same period is 77.6%, so Frontier on ATL to BOS runs 11 points behind the country as a whole. Across a thousand flights that is about 112 extra late arrivals.

On time

66.4%

Arrivals under 15 minutes late, of 390 completed flights

Avg delay

57 min

Across delayed arrivals only, not all flights

Cancelled

2.50%

National rate is 1.81%

Whole route

74.5%

Every carrier on ATL to BOS, 4,935 flights

These figures cover 400 flights between July 2025 and June 2026. Beyond the headline rate, 10.8% 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.

Carrier by carrier

Frontier against every carrier on ATL to BOS

Frontier flew 400 of the 4,935 flights on ATL to BOS, about 8% of it. Its 66.4% on time is 8 points worse than the route as a whole, which runs 74.5%. Ranked by on-time rate it is number three of four carriers on the route, where the range runs from Delta at 76.2% to Spirit at 61.9%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The two carriers here are closely matched: 5 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.

On-time performance by carrier on ATL to BOS
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	3,666	76.2%	59 min	1.72%	B
JetBlue Airways	848	71.2%	83 min	2.71%	C
Frontier Airlines (this page)	400	66.4%	57 min	2.50%	C
Spirit Airlinesthin sample	21	61.9%	57 min	0.00%	D+

No carrier stands out. Delta tops the table at 76.2%, 5 points clear of the bottom, which is inside the range this kind of sample moves year to year.

Departure window

When Frontier runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 17 points, against 5 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am153 flights75.5%
8am–11am65 flights65.6%
11am–2pm—
2pm–5pm—
5pm–8pm—
8pm–5am182 flights58.9%

Scale runs 50% to 80%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 58.9% on time, against 75.5% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 8pm–5am window is the busiest, with 182 flights scheduled in it.

Across the year

Frontier on ATL to BOS through the year

Jul–Sep 202542 flights71.4%
Oct–Dec 202580 flights67.5%
Jan–Mar 202696 flights51.1%
Apr–Jun 2026182 flights72.6%

Scale runs 45% to 80%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 66.4% on time across 400 flights.

Frontier on ATL to BOS did not run the same all year. Its best quarter was Apr–Jun 2026 at 72.6% on time and its weakest Jan–Mar 2026 at 51.1%, a swing of 21 points on roughly 100 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.

Across the week, Wednesday is the strongest day at 72.1% on time and Sunday the weakest at 55.4%. 17 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Frontier runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 47% of the 7,518 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.

Late-arriving aircraft
47%
Carrier
44%
National Airspace System
9%

47% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 7,518 reported delay minutes here, that single category outweighs weather by 47 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 7,518 reported delay minutes.

The largest share of delay minutes, 44%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 3,294 of the 7,518 delay minutes reported here.

Cancellations run at 2.50%, against 1.81% nationally. That is about one flight in 40 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 stage length

What a delay here costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.8% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.

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. 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.

The return leg runs 65.2% on time across 399 flights, within about a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

One caution: this is a thin sample. 400 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 Frontier on ATL to BOS

Put together: treat all of this as provisional. 400 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 66.4% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 390 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures