About 1 in 5 DL 639 flights from Los Angeles arrived 15+ minutes late, diverted or cancelled over the past year (21%); 3.0% were cancelled. The typical flight landed 5 minutes early.
DL 639: LAX → BOS
Scheduled to leave Los Angeles at 7:55 a.m. local time. Over the past year it arrived on time 79% of the time (365 flights), better than other DL flights on the route at that hour (74%). Last seen in the data Aug 31, 2026.
Month by month
By day of week
| Day | Flights | On time |
|---|---|---|
| Monday | 53 | 77% |
| Tuesday | 52 | 77% |
| Wednesday | 52 | 79% |
| Thursday | 52 | 87% |
| Friday | 52 | 90% |
| Saturday | 52 | 69% |
| Sunday | 52 | 75% |
Why it was late
All flights LAX → BOS · Connecting off DL 639? Check the risk
Questions
How often is DL 639 from LAX to BOS late?
Delta Air Lines 639 from Los Angeles, CA to Boston, MA arrived 15 or more minutes late, was diverted or was cancelled on 21% of 365 scheduled flights between September 2025 and August 2026. 3.0% were cancelled.
Flight numbers change. Figures cover flights with this airline, number and route only. "Likely range" is the 95% interval for the true on-time rate given the number of flights. This is history, not live status: check Delta Air Lines for today's flight. Method.