Route reliability record
BOS→ATL
Boston to Atlanta
- Flights
- 4,903
- Period
- June 2025 to May 2026
- Distance
- 946 mi
- Carriers
- 4
This route lands a B, level with the national rate of 77.4%. Roughly 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 4,903 flights, of which Delta Air Lines flew 3,656 at 81.3% on time.
The US average over the same twelve months is 77.4%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
77.9%
Arrivals under 15 minutes late, of 4,794 completed flights
Avg delay
69 min
Across delayed arrivals only, not all flights
Cancelled
1.98%
National rate is 1.80%
Best carrier
Delta
81.3% on time across 3,656 flights
These figures cover 4,903 flights between June 2025 and May 2026. Beyond the headline rate, 8.3% 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
Which airline is most reliable on BOS to ATL
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 81.3% of the time; JetBlue Airways manages 68.9%. Sample sizes sit next to every figure, because a two-point gap across 849 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Spirit Airlinesthin sample | 49 | 83.7% | 98 min | 0.00% | B+ |
| Delta Air Lines | 3,656 | 81.3% | 73 min | 1.86% | B |
| JetBlue Airways | 849 | 68.9% | 65 min | 2.36% | C |
| Frontier Airlinesthin sample | 349 | 63.4% | 52 min | 2.58% | D |
The spread between Delta and JetBlue is 12 points, wide enough that it should decide the booking. On a hundred trips that is 12 more arrivals inside the on-time window.
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 23 points, against 12 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am938 flights83.0%
- 8am–11am1,202 flights86.6%
- 11am–2pm864 flights80.7%
- 2pm–5pm710 flights72.3%
- 5pm–8pm878 flights67.2%
- 8pm–5am311 flights63.8%
Scale runs 55% to 90%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 63.8% on time, against 86.6% 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.
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.
December is the weak month at 69.0% on time, against 82.8% in September. 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.
Across the week, Wednesday is the strongest day at 85.8% on time and Sunday the weakest at 71.2%. 15 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 73,000 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.
- 43%Late-arriving aircraft
- 34%Carrier
- 22%National Airspace System
- 1%Extreme weather
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 73,000 reported delay minutes here, that single category outweighs weather by 41 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 practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 86.6% on time here.
Cancellations sit at 1.98% against a national 1.80%, which is ordinary. Diversions add another 0.24%.
Connections and stage length
What a delay here actually costs
8.3% of arrivals land an hour or more late, close to the national 8.2%. 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 73.6% on time across 4,904 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 4,903 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. September runs 82.8% 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.
Common questions
BOS to ATL questions
How often is BOS to ATL delayed?
Roughly 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 22.1% of the 4,903 flights in this analysis, against 22.6% 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 81.3% on time across 3,656 flights. JetBlue Airways is at the other end on 68.9%, a gap of 12 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 86.6% on time. The 8pm–5am window is the weakest at 63.8%, 23 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 82.8% in September. 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.
Related
Where to go next
- ATL to BOS — the return legseparate record
- Boston Logan International (BOS) delay statistics
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Spirit Airlines on-time record83.7%
- Delta Air Lines on-time record81.3%
- JetBlue Airways on-time record68.9%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
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, June 2025 to May 2026. Updated monthly. How this data is collected.