Flight profile · Delta Air Lines
DL821
Atlanta (ATL) to Boston (BOS) · scheduled 4:00 PM – 6:22 PM
How DL821 performs
905 operations, 2023-07-01 to 2026-06-30.
DL821 arrived on time 69.7% of the time, against 77.1% for all ATL → BOS flights — this specific departure is 7.4 percentage points worse than the route as a whole. Against Delta Air Lines’s own flights on this route it is 9.4 points worse.
Source: US DOT Bureau of Transportation Statistics · 905 operations between 2023-07-01 to 2026-06-30
Against the rest of the route
| On time | Cancelled | Median delay | Severe | Flights | |
|---|---|---|---|---|---|
| DL821 | 69.7% | 0.77% | -1 min | 11.1% | 905 |
| Delta Air Lines on ATL → BOS | 79.1% | 1.01% | -6 min | 6.5% | 10,893 |
| All ATL → BOS flights | 77.1% | 1.26% | -6 min | 7.9% | 15,009 |
Source: FlyerIntel analysis of US DOT BTS data · 2023-07-01 to 2026-06-30
By day of week
Does DL821 run worse on particular days?
Saturday is historically the most reliable day and Thursday the least, a gap of 11.9 percentage points.
Source: FlyerIntel analysis of US DOT BTS data · 2023-07-01 to 2026-06-30 · Days with fewer than 120 operations are not scored.
Other routes DL821 has flown
A flight number is a slot in a schedule, and carriers reassign it. These are the other city pairs this number served in the analysis period.
| Route | Operated | Flights | On time |
|---|---|---|---|
| ATL→ORF Atlanta to Norfolk | 2024-01-08 – 2024-03-08 | 50 | — |
| ORF→ATL Norfolk to Atlanta | 2024-01-08 – 2024-03-08 | 50 | — |
| DFW→LAX Dallas–Fort Worth to Los Angeles | 2023-10-09 – 2023-11-04 | 27 | — |
| ALB→ATL Albany to Atlanta | 2023-07-02 – 2023-07-04 | 3 | — |
| ATL→ALB Atlanta to Albany | 2023-07-02 – 2023-07-04 | 3 | — |
Because the same number has served different journeys, the statistics above describe only the route DL821 currently operates. Blending them would produce an average of two different flights.
Data and methodology
Calculated by FlyerIntel from 905 records of DL821 operating ATL → BOS, published by the US DOT Bureau of Transportation Statistics. A flight counts as delayed when it arrives 15 or more minutes after schedule. Cancelled and diverted flights are excluded from the on-time rate and reported separately. Flight numbers are resolved as carrier plus number plus route, because the same number serves different routes over time.