Route reliability record

BOS→ATL

Boston to Atlanta

Flights: 4,931
Period: July 2025 to June 2026
Distance: 946 mi
Carriers: 4

This route lands a B, about a point better than the national rate of 77.6%. About one flight in five arrive 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 4,931 flights, of which Delta Air Lines flew 3,662 at 82.1% on time.

Delta Air Lines is the most reliable of the three carriers covered here at 82.1% on time across 3,662 flights.

On time

78.5%

Arrivals under 15 minutes late, of 4,822 completed flights

Avg delay

69 min

Across delayed arrivals only, not all flights

Cancelled

1.99%

National rate is 1.81%

Best carrier

Delta

82.1% on time across 3,662 flights

These figures cover 4,931 flights between July 2025 and June 2026. The median arrival is 7 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.

Carrier by carrier

Which airline is most reliable on BOS to ATL

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 82.1% of the time; Frontier Airlines manages 65.2%. Sample sizes sit next to every figure, because a two-point gap across 399 flights means less than a ten-point one.

On-time performance by carrier on BOS to ATL
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	3,662	82.1%	75 min	1.77%	B
Spirit Airlinesthin sample	20	70.0%	61 min	0.00%	C+
JetBlue Airways	850	69.6%	63 min	2.35%	C
Frontier Airlines	399	65.2%	52 min	3.26%	C−

Frontier Airlines cancels 3.3% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.

Departure window

The best time of day to leave

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 22 points, against 17 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am971 flights82.5%
8am–11am1,178 flights86.5%
11am–2pm851 flights80.6%
2pm–5pm734 flights75.2%
5pm–8pm908 flights69.0%
8pm–5am289 flights64.6%

Scale runs 55% to 90%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 64.6% on time, against 86.5% for the 8am–11am 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 8am–11am window is the busiest, with 1,178 flights scheduled in it.

Across the year

When delays peak on this route

This route's year swings by 14 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.

Darker means more delays. Figures are on-time percentages.June best, December worst

December is the weak month at 69.0% on time, against 83.0% in June. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. June was the busiest month here, with 465 flights.

Across the week, Wednesday is the strongest day at 85.7% on time and Sunday the weakest at 71.5%. 14 points is a smaller lever than departure hour, but it is free.

Delay causes

Why this route gets delayed

One category carries most of the weight here. Late-arriving aircraft accounts for 43% of the 72,000 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
43%
Carrier
34%
National Airspace System
22%
Extreme weather
1%

43% 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 72,000 reported delay minutes here, that single category outweighs weather by 43 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 71,670 reported delay minutes.

The largest share of delay minutes, 34%, 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 25,000 of the 72,000 delay minutes reported here.

Cancellations sit at 1.99% against a national 1.81%, which is ordinary. Diversions add another 0.22%.

Connections and stage length

What a delay here actually costs

7.9% 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 are the a little over an hour kind, 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. 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 is a different operation and performs like one: it runs 74.5% on time across 4,935 flights, 4 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 4 points of difference.

The sample behind these figures is 4,931 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.

What to do with this

Booking this route

Put together: the calendar is the biggest lever here, not the carrier or the hour. June runs 83.0% on time and December 69.0%, a swing of 14 points. If the dates move at all, move them out of December before you think about anything else. 4,822 completed flights over 12 months sit behind that.

Common questions

BOS to ATL questions

How often is BOS to ATL delayed?

About one flight in five arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 21.5% of the 4,931 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.

Which airline is most reliable on BOS to ATL?

Delta Air Lines leads at 82.1% on time across 3,662 flights. Frontier Airlines is at the other end on 65.2%, a gap of 17 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.

What time of day has the fewest delays on BOS to ATL?

The 8am–11am departure window is the strongest at 86.5% on time. The 8pm–5am window is the weakest at 64.6%, 22 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.

How bad are December delays on BOS to ATL?

December is the weakest month at 69.0% on time, compared with 83.0% in June. Across the year that is 14 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.

Where to go next

Direction matters. BOS to ATL and ATL to BOS are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.

Key figures