Flight Reliability
DL 4017 · Delta Air Lines
Seattle → PSC (SEA–PSC)
90
Nerd Approved
WanderNerd Reliability Score
- 84%
- Arrive within 15 minutes
- 8 min
- Average arrival delay
- 0.3%
- Cancelled
- 8 min early
- Median arrival delay
Based on 365 historical flights. Data through May 2026.
What the data says
The late departure is the smart one here.
DL 4017 departing between 6–9 PM arrived on time 100% of the time, versus 83% between 9 PM–12 AM.
Skip Thursday if you can.
DL 4017 arrived on time 92% of the time on Tuesdays. On Thursdays: 78%.
It basically never cancels.
Out of 365 scheduled flights, only 0.3% were cancelled.
Recent months have been rougher.
DL 4017 arrived on time 77% of the time over the last three months in the data, compared with 84% in the three months before that.
The breakdown
- Mon85%(52 flights)
- Tue92%(52 flights)
- Wed83%(52 flights)
- Thu78%(51 flights)
- Fri84%(51 flights)
- Sat87%(52 flights)
- Sun79%(53 flights)
- 3–6 PM—(7 flights)
- 6–9 PM100%(23 flights)
- 9 PM–12 AM83%(333 flights)
84%
May
Jun 73% → May 84% on time
| Month | On-time percentage | Flights |
|---|---|---|
| June 2025 | 73% | 30 |
| July 2025 | 90% | 31 |
| August 2025 | 90% | 31 |
| September 2025 | 90% | 30 |
| October 2025 | 94% | 31 |
| November 2025 | 87% | 30 |
| December 2025 | 87% | 31 |
| January 2026 | 81% | 31 |
| February 2026 | 85% | 27 |
| March 2026 | 73% | 30 |
| April 2026 | 73% | 30 |
| May 2026 | 84% | 31 |
- Departures on time
- 85%
- Diverted
- 0.3%
- Flights flown
- 363
- 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.