Flight Reliability
DL 1240 · Delta Air Lines
Atlanta → Detroit (ATL–DTW)
90
Nerd Approved
WanderNerd Reliability Score
- 84%
- Arrive within 15 minutes
- 4 min
- Average arrival delay
- 0.3%
- Cancelled
- 5 min early
- Median arrival delay
Based on 365 historical flights. Data through May 2026.
What the data says
Sunday scaries are real for this one.
DL 1240 arrived on time 90% of the time on Thursdays. On Sundays: 77%.
A bit ahead of the ATL–DTW route.
DL 1240 arrived on time 84% of the time, versus 78% across the ATL–DTW route.
It basically never cancels.
Out of 365 scheduled flights, only 0.3% were cancelled.
Trending in the right direction.
DL 1240 arrived on time 87% of the time over the last three months in the data, compared with 77% in the three months before that.
The breakdown
- Mon89%(52 flights)
- Tue81%(52 flights)
- Wed89%(52 flights)
- Thu90%(52 flights)
- Fri83%(52 flights)
- Sat77%(52 flights)
- Sun77%(52 flights)
87%
May
Jun 73% → May 87% on time
| Month | On-time percentage | Flights |
|---|---|---|
| June 2025 | 73% | 30 |
| July 2025 | 84% | 31 |
| August 2025 | 90% | 31 |
| September 2025 | 87% | 30 |
| October 2025 | 84% | 31 |
| November 2025 | 93% | 29 |
| December 2025 | 74% | 31 |
| January 2026 | 81% | 31 |
| February 2026 | 75% | 28 |
| March 2026 | 87% | 31 |
| April 2026 | 87% | 30 |
| May 2026 | 87% | 31 |
- Departures on time
- 81%
- Diverted
- 0%
- Flights flown
- 364
- Months covered
- 12
Same route, other flights
Keep nerding
Based on 365 historical flights, because apparently we checked. Historical flight data: U.S. Bureau of Transportation Statistics, June 2025 – May 2026. Data through May 2026. How we calculate this.