About 1 in 3 DL 399 flights from Boston arrived 15+ minutes late, diverted or cancelled over the past year (31%); 0.4% were cancelled. The typical flight landed 4 minutes early.
DL 399: BOS → ATL
Scheduled to leave Boston at 4:30 p.m. local time. Over the past year it arrived on time 69% of the time (239 flights), in line with other DL flights on the route at that hour (69%). Last seen in the data Aug 31, 2026.
Month by month
By day of week
| Day | Flights | On time |
|---|---|---|
| Monday | 37 | 70% |
| Tuesday | 36 | 64% |
| Wednesday | 36 | 81% |
| Thursday | 36 | 67% |
| Friday | 36 | 75% |
| Saturday | 23 | 74% |
| Sunday | 35 | 51% |
Why it was late
All flights BOS → ATL · Connecting off DL 399? Check the risk
Questions
How often is DL 399 from BOS to ATL late?
Delta Air Lines 399 from Boston, MA to Atlanta, GA arrived 15 or more minutes late, was diverted or was cancelled on 31% of 239 scheduled flights between September 2025 and August 2026. 0.4% were cancelled.
Flight numbers change. Figures cover flights with this airline, number and route only. "Likely range" is the 95% interval for the true on-time rate given the number of flights. This is history, not live status: check Delta Air Lines for today's flight. Method.