Carrier route record
DLATL→BOS
Delta Air Lines · Atlanta to Boston
- Flights
- 3,666
- Period
- July 2025 to June 2026
- Share of route
- 74%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.
Delta on ATL to BOS lands a B, about a point worse than the national rate of 77.6%. About one flight in four arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 3,666 flights. The strongest carrier on the route with a full sample, JetBlue Airways, flew 848 at 71.2% on time.
The US average over the same twelve months is 77.6%, so there is little to separate Delta on ATL to BOS from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
76.2%
Arrivals under 15 minutes late, of 3,600 completed flights
Avg delay
59 min
Across delayed arrivals only, not all flights
Cancelled
1.72%
National rate is 1.81%
Whole route
74.5%
Every carrier on ATL to BOS, 4,935 flights
These figures cover 3,666 flights between July 2025 and June 2026. The median arrival is 5 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
Delta against every carrier on ATL to BOS
Delta flew 3,666 of the 4,935 flights on ATL to BOS, most of the route. Its 76.2% on time is 2 points better than the route as a whole, which runs 74.5%. Ranked by on-time rate it is first 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.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines (this page) | 3,666 | 76.2% | 59 min | 1.72% | B |
| JetBlue Airways | 848 | 71.2% | 83 min | 2.71% | C |
| Frontier Airlines | 400 | 66.4% | 57 min | 2.50% | C |
| Spirit Airlinesthin sample | 21 | 61.9% | 57 min | 0.00% | D+ |
No carrier stands out. JetBlue tops the table at 71.2%, 5 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Delta flight numbers on ATL to BOS
- DL 85509:1088.1% · 365 flights
- DL 86522:4079.8% · 360 flights
- DL 72613:5969.5% · 353 flights
- DL 35012:4075.5% · 348 flights
- DL 30019:5968.5% · 333 flights
- DL 98707:0089.8% · 329 flights
- DL 82117:5568.4% · 325 flights
- DL 259514:5966.0% · 322 flights
- DL 86211:1084.3% · 286 flights
- DL 51816:2058.1% · 275 flights
Departure window
When Delta runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 27 points, against 5 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am345 flights90.2%
- 8am–11am654 flights89.6%
- 11am–2pm716 flights79.1%
- 2pm–5pm785 flights63.5%
- 5pm–8pm432 flights68.1%
- 8pm–5am734 flights73.0%
Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 90.2% of the time, against 63.5% for the afternoon window. That is 27 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 2pm–5pm window is the busiest, with 785 flights scheduled in it.
Across the year
Delta on ATL to BOS through the year
July is the worst month at 66.6% on time, 18 points below August, the best at 84.4%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. May was the busiest month here, with 329 flights.
Across the week, Saturday is the strongest day at 83.5% on time and Sunday the weakest at 70.2%. 13 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Delta runs late on this route
One category carries most of the weight here. National Airspace System accounts for 42% of the 51,000 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.
- 42%National Airspace System
- 37%Carrier
- 15%Late-arriving aircraft
- 5%Extreme weather
- 0%Security
The largest share of delay minutes, 37%, 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 19,000 of the 51,000 delay minutes reported here. The split is drawn from 50,601 reported delay minutes.
42% 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 21,000 minutes out of 51,000, against a national NAS share of 21%.
Cancellations sit at 1.72% against a national 1.81%, which is ordinary. Diversions add another 0.08%.
Connections and stage length
What a delay here costs
7.7% 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 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 82.1% on time across 3,662 flights, 6 points above 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 6 points of difference.
The sample behind these figures is 3,666 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 Delta on ATL to BOS
Put together: the calendar is the biggest lever here, not the carrier or the hour. August runs 84.4% on time and July 66.6%, a swing of 18 points. If the dates move at all, move them out of July before you think about anything else. 3,600 completed flights over 12 months sit behind that.
Related
Where to go next
- ATL to BOS, every carrier
- Delta on BOS to ATL, the return leg
- JetBlue Airways on ATL to BOS71.2%
- Frontier Airlines on ATL to BOS66.4%
- Delta Air Lines network-wide record
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Boston Logan International (BOS) delay statistics
- The best time of day to fly, according to 7.04 million flight records
- Worst months to fly in the US, ranked by the data
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.