Flight number record
DL 350
Delta Air Lines · Atlanta to Boston
- Route
- ATL → BOS
- Departs
- 12:40
- Flights
- 339
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 350, check with Delta Air Lines.
DL 350 sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 3 points worse than the national rate of 77.3%. The late ones land roughly 50 minutes behind schedule. That rests on 339 flights, with a median arrival 3 minutes early.
Key figures
On time
74.6%
Arrivals under 15 minutes late, of 331 completed flights
Avg delay
52 min
Across delayed arrivals only, not all flights
Cancelled
2.36%
National rate is 1.89%
1 hour+ late
6.6%
National rate is 8.3%
These figures cover 339 flights between September 2025 and August 2026. The median arrival is 3 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 DL 350 flies
DL 350 flies ATL to BOS without a single fixed slot. Its most common scheduled departure was 12:40, used on 46 of 339 flights, with 12:15 (41 flights) and 11:50 (34 flights) next.
- Departs 12:4046 flights13.6%
- Departs 12:1541 flights12.1%
- Departs 11:5034 flights10.0%
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 12:40 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.3%, and DL 350 runs 4 points worse at 74.6%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.
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Against the route
DL 350 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 DL 350 is 2 points ahead of it. Delta flew 3,731 flights on the same city pair under all its flight numbers, including this one, and those ran 74.4% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight trails by 7 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 350thin sample | 339 | 74.6% | 52 min | 2.36% | C |
| All Delta Air Lines on ATL–BOS | 3,731 | 74.4% | 61 min | 1.82% | C |
| All carriers on ATL–BOS | 5,054 | 72.8% | 66 min | 2.30% | C |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 350 quarter by quarter
DL 350 did not run the same all year. Its best quarter was Jan–Mar 2026 at 80.8% on time and its weakest Jul–Sep 2025 at 66.7%, a swing of 14 points on roughly 68 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 202530 flights66.7%
- Oct–Dec 202590 flights74.2%
- Jan–Mar 202684 flights80.8%
- Apr–Jun 202682 flights76.5%
- Jul–Sep 202653 flights67.9%
Scale runs 60% to 85%.
By weekday, DL 350 did best on Wednesday at 80.8% on time and worst on Thursday at 67.3%. Each day rests on about 48 flights, so a gap of 14 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late DL 350 runs when it is late
The 84 late arrivals split 32 under half an hour, 30 between 30 and 60 minutes, and 22 an hour or more.
- 15+ min early68 flights20.5%
- Within 15 min179 flights54.1%
- 15–29 min late32 flights9.7%
- 30–59 min late30 flights9.1%
- 1–2 hours late18 flights5.4%
- 2+ hours late4 flights1.2%
Scale runs 0% to 100%.
Share of 331 completed flights by arrival against schedule.
17 of 87 late departures made up the time and arrived on time, 20% of them. 14 flights left on time and still arrived late.
The worst days
Worst days for DL 350
The latest arrival of the period was on 21 July 2026, 5 hours 38 minutes behind schedule; most of its delay minutes were filed as national airspace system delay. The same cause led on four of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 21 July 2026 | 5 hours 38 minutes | National Airspace System |
| 7 March 2026 | 2 hours 55 minutes | Carrier |
| 14 October 2025 | 2 hours 32 minutes | National Airspace System |
| 25 May 2026 | 2 hours 3 minutes | National Airspace System |
| 6 July 2026 | 1 hour 59 minutes | National Airspace System |
Delay causes
Why DL 350 runs late
National Airspace System accounts for 59% of the 4,354 delay minutes carriers reported here, and the remaining four split what is left.
- 59%National Airspace System
- 32%Carrier
- 8%Late-arriving aircraft
- 2%Extreme weather
59% 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 2,562 minutes out of 4,354, against a national NAS share of 21%. The split is drawn from 4,354 delay minutes reported on DL 350.
Cancellations sit at 2.36% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
6.6% 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 50 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 339 flights under DL 350 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. 339 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 DL 350
For a booking, read DL 350 as 74.6% on time with 2.36% cancelled over 339 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 2595 on the same route62.5%
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Boston Logan International (BOS) delay statistics
- Delta Air Lines on-time record
- Every Delta Air Lines 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 Delta Air Lines’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.