Flight OddsDL4021 SLC → BOI
Delta Air Lines · Salt Lake City, UT to Boise, ID · 151 flights observed, 2025-07-06 to 2025-12-19 · 290 mi
DL4021 covers more than one route in the data window — the stats below are for SLC → BOI, the one it has flown most recently. The others are linked under “Other routes”.
On-time arrival
89%
Median delay
-9 min
90th percentile
+17 min
Cancellation rate
0%
How often is DL4021 on time?
Across 151 flights on SLC → BOI from 2025-07-06 to 2025-12-19, DL4021 arrived within 15 minutes of schedule 89% of the time. The median arrival delay was -9 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).
| Arrival | Flights | Share |
|---|---|---|
| Early / on-time | 135 | 89% |
| 16-30 min | 5 | 3% |
| 31-60 min | 8 | 5% |
| 61-120 min | 3 | 2% |
| 2+ hrs | 0 | 0% |
Performance by month
| Month | Flights | On-time | Avg delay |
|---|---|---|---|
| 2025-07 | 23 | 87% | +2 min |
| 2025-08 | 26 | 88% | -4 min |
| 2025-09 | 26 | 85% | -2 min |
| 2025-10 | 30 | 100% | -7 min |
| 2025-11 | 27 | 85% | -5 min |
| 2025-12 | 19 | 89% | -3 min |
Performance by day of week
| Day | Flights | On-time |
|---|---|---|
| Mon | 24 | 96% |
| Tue | 24 | 92% |
| Wed | 24 | 83% |
| Thu | 23 | 96% |
| Fri | 23 | 83% |
| Sat | 9 | 89% |
| Sun | 24 | 88% |
Other routes
Related
Based on US Department of Transportation Bureau of Transportation Statistics on-time data. Loading live conditions and full charts…