Flight Reliability
DL 639 · Delta Air Lines
Los Angeles → Boston (LAX–BOS)
84
Pretty Reliable
WanderNerd Reliability Score
- 85%
- Arrive within 15 minutes
- 3 min
- Average arrival delay
- 2.2%
- Cancelled
- 5 min early
- Median arrival delay
Based on 365 historical flights. Data through May 2026.
What the data says
Saturdays have been rough.
DL 639 arrived on time 90% of the time on Thursdays and just 75% on Saturdays. That gap is worth planning around.
A bit ahead of the LAX–BOS route.
DL 639 arrived on time 85% of the time, versus 79% across the LAX–BOS route.
A bit ahead of the Delta Air Lines network.
DL 639 arrived on time 85% of the time, versus 81% across the Delta Air Lines network.
The breakdown
- Mon84%(50 flights)
- Tue86%(50 flights)
- Wed81%(52 flights)
- Thu90%(52 flights)
- Fri90%(52 flights)
- Sat75%(51 flights)
- Sun86%(50 flights)
94%
May
Jun 97% → May 94% on time
| Month | On-time percentage | Flights |
|---|---|---|
| June 2025 | 97% | 30 |
| July 2025 | 100% | 31 |
| August 2025 | 100% | 31 |
| September 2025 | 73% | 30 |
| October 2025 | 71% | 31 |
| November 2025 | 75% | 28 |
| December 2025 | 87% | 30 |
| January 2026 | 86% | 28 |
| February 2026 | 78% | 27 |
| March 2026 | 73% | 30 |
| April 2026 | 80% | 30 |
| May 2026 | 94% | 31 |
- Departures on time
- 91%
- Diverted
- 0%
- Flights flown
- 357
- 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.