Flight Reliability
DL 1128 · Delta Air Lines
Seattle → Salt Lake City (SEA–SLC)
100
Nerd Approved
WanderNerd Reliability Score
- 93%
- Arrive within 15 minutes
- 7 min early
- Average arrival delay
- 0.3%
- Cancelled
- 14 min early
- Median arrival delay
Based on 365 historical flights. Data through May 2026.
What the data says
Friday has been the better bet.
A small edge: 96% on time on Fridays against 90% on Tuesdays.
Better than the SEA–SLC route average.
DL 1128 arrived on time 93% of the time, versus 84% across the SEA–SLC route.
Better than the Delta Air Lines network average.
DL 1128 arrived on time 93% of the time, versus 81% across the Delta Air Lines network.
It basically never cancels.
Out of 365 scheduled flights, only 0.3% were cancelled.
The breakdown
- Mon94%(51 flights)
- Tue90%(52 flights)
- Wed92%(52 flights)
- Thu94%(52 flights)
- Fri96%(52 flights)
- Sat92%(52 flights)
- Sun94%(53 flights)
100%
May
Jun 90% → May 100% on time
| Month | On-time percentage | Flights |
|---|---|---|
| June 2025 | 90% | 30 |
| July 2025 | 100% | 31 |
| August 2025 | 97% | 31 |
| September 2025 | 93% | 30 |
| October 2025 | 87% | 31 |
| November 2025 | 100% | 30 |
| December 2025 | 100% | 31 |
| January 2026 | 97% | 31 |
| February 2026 | 79% | 28 |
| March 2026 | 80% | 30 |
| April 2026 | 97% | 30 |
| May 2026 | 100% | 31 |
- Departures on time
- 94%
- 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.