DL1399
DL1399 (Delta Air Lines) is a multi-stop service on 3 routes, busiest Boston to Miami. Of 1,010 departures recorded from October 2024 to July 2026, 83.9% left on time, according to the US BTS.
- On-time departures83.9%of 1,010 flights
- Average delay14.3 min
- July 202662▲ 0.0%vs July 2025
- Cancelled1.1%
- Legs flown under this number3
Recorded departures by month
All legs under this number combined; see the leg table.
The most recent periods19 periods
| Period | Departures 2025 | Departures 2026 | Change vs last year |
|---|---|---|---|
| January | 27 | 29 | ▲ 7.4% |
| February | 28 | 25 | ▼ 10.7% |
| March | 54 | 30 | ▼ 44.4% |
| April | 60 | 30 | ▼ 50.0% |
| May | 62 | 56 | ▼ 9.7% |
| June | 60 | 60 | 0.0% |
| July | 62 | 62 | 0.0% |
| August | 62 | – | – |
| September | 60 | – | – |
| October | 62 | – | in progress |
| November | 60 | – | – |
| December | 45 | – | – |
| Year to date (Jan–Jul) | 353 | 292 | ▼ 17.3% |
according to the US BTS · October 2024 → July 2026
On-time departures by month
On time = departure within 15 minutes of schedule. Non-cancelled flights with a recorded delay only.
The most recent periods19 periods
| Period | On time 2025 | On time 2026 | Change vs last year |
|---|---|---|---|
| January | 88.9% | 85.2% | ▼ 4.2% |
| February | 89.3% | 91.3% | ▲ 2.3% |
| March | 79.6% | 93.3% | ▲ 17.2% |
| April | 80.0% | 93.3% | ▲ 16.7% |
| May | 80.7% | 83.9% | ▲ 4.1% |
| June | 75.0% | 83.3% | ▲ 11.1% |
| July | 86.4% | 86.7% | ▲ 0.3% |
| August | 95.2% | – | – |
| September | 81.7% | – | – |
| October | 64.5% | – | in progress |
| November | 84.5% | – | – |
| December | 75.6% | – | – |
| Year-to-date average (Jan–Jul) | 82.8% | 88.2% | ▲ 6.4% |
according to the US BTS · October 2024 → July 2026
Average departure delay by month
according to the US BTS · October 2024 → July 2026
Cancelled departures by month
The most recent periods19 periods
| Period | Cancelled 2025 | Cancelled 2026 | Change vs last year |
|---|---|---|---|
| January | 0 | 2 | – |
| February | 0 | 2 | – |
| March | 0 | 0 | – |
| April | 0 | 0 | – |
| May | 0 | 0 | – |
| June | 0 | 0 | – |
| July | 3 | 2 | ▼ 33.3% |
| August | 0 | – | – |
| September | 0 | – | – |
| October | 0 | – | in progress |
| November | 2 | – | – |
| December | 0 | – | – |
| Year to date (Jan–Jul) | 3 | 6 | ▲ 100.0% |
according to the US BTS · October 2024 → July 2026
This is a historical record of departures already flown, not a forecast for your flight.
Several legs: the headline figure averages all of them. See the leg table.
Cancellation share
- Not cancelled 98.9% 999
- Cancelled 1.1% 11
Share of all recorded flights in the period, all legs. · Oct 12, 2024 → Jul 31, 2026
On time, leg by leg
Departures within 15 minutes of schedule; small figure = departures recorded.
Legs flown under this number
2| Routes | Distance (km) | Avg delay | On time | Departures |
|---|---|---|---|---|
| BOS MIA Boston Logan International Airport – Miami International Airport | 2,028 | 9.0 min | 91.2% | 620 |
| MIA BOS Miami International Airport – Boston Logan International Airport | 2,028 | 21.0 min | 73.2% | 372 |
Monthly figures
| Period | Departures | With departure delay recorded | On time | Cancelled |
|---|---|---|---|---|
| October 2024 | 20 | 20 | 100.0% | 0 |
| November 2024 | 30 | 30 | 96.7% | 0 |
| December 2024 | 26 | 26 | 88.5% | 0 |
| January 2025 | 27 | 27 | 88.9% | 0 |
| February 2025 | 28 | 28 | 89.3% | 0 |
| March 2025 | 54 | 54 | 79.6% | 0 |
| April 2025 | 60 | 60 | 80.0% | 0 |
| May 2025 | 62 | 62 | 80.7% | 0 |
| June 2025 | 60 | 60 | 75.0% | 0 |
| July 2025 | 62 | 59 | 86.4% | 3 |
| August 2025 | 62 | 62 | 95.2% | 0 |
| September 2025 | 60 | 60 | 81.7% | 0 |
| October 2025 | 62 | 62 | 64.5% | 0 |
| November 2025 | 60 | 58 | 84.5% | 2 |
| December 2025 | 45 | 45 | 75.6% | 0 |
| January 2026 | 29 | 27 | 85.2% | 2 |
| February 2026 | 25 | 23 | 91.3% | 2 |
| March 2026 | 30 | 30 | 93.3% | 0 |
| April 2026 | 30 | 30 | 93.3% | 0 |
| May 2026 | 56 | 56 | 83.9% | 0 |
| June 2026 | 60 | 60 | 83.3% | 0 |
| July 2026 | 62 | 60 | 86.7% | 2 |