How often is DL3999 on time?

Across 54 flights on SEA → SJC from 2025-10-06 to 2025-12-19, DL3999 arrived within 15 minutes of schedule 89% of the time. The median arrival delay was -4 min, and the worst 10% of flights arrived +17 min or later. 0% of flights were cancelled.

Delay distribution

Arrival delay for completed flights (excludes cancellations and diversions).

Performance by month

Performance by day of week

Other routes

• DL3999 on SEA → SNA (79 flights)
• DL3999 on SNA → SEA (79 flights)
• DL3999 on DTW → PIT (36 flights)
• DL3999 on PIT → DTW (36 flights)
• DL3999 on CLE → MSP (9 flights)
• DL3999 on MSP → CLE (9 flights)
• DL3999 on SJC → SLC (2 flights)
• DL3999 on SLC → SJC (2 flights)
• DL3999 on SJC → SEA (54 flights)
• DL3999 on DTW → ROC (1 flights)
• DL3999 on ROC → DTW (1 flights)
• DL3999 on DTW → MKE (4 flights)
• DL3999 on MKE → DTW (3 flights)

Related

• All Delta Air Lines flights on SEA → SJC
• Compare airlines on SEA → SJC
• Delta Air Lines on the return, SJC → SEA