Flight OddsUA399 ORD → BOS
United Airlines · Chicago, IL to Boston, MA · 224 flights observed, 2025-07-01 to 2026-02-11 · 867 mi
UA399 covers more than one route in the data window — the stats below are for ORD → BOS, the one it has flown most recently. The others are linked under “Other routes”.
On-time arrival
63%
Median delay
+2 min
90th percentile
+69 min
Cancellation rate
3%
How often is UA399 on time?
Across 224 flights on ORD → BOS from 2025-07-01 to 2026-02-11, UA399 arrived within 15 minutes of schedule 63% of the time. The median arrival delay was +2 min, and the worst 10% of flights arrived +69 min or later. 3% of flights were cancelled.
Delay distribution
Arrival delay for completed flights (excludes cancellations and diversions).
| Arrival | Flights | Share |
|---|---|---|
| Early / on-time | 138 | 63% |
| 16-30 min | 20 | 9% |
| 31-60 min | 33 | 15% |
| 61-120 min | 15 | 7% |
| 2+ hrs | 12 | 6% |
Performance by month
| Month | Flights | On-time | Avg delay |
|---|---|---|---|
| 2025-07 | 30 | 67% | +6 min |
| 2025-08 | 30 | 83% | +8 min |
| 2025-09 | 30 | 30% | +52 min |
| 2025-10 | 31 | 55% | +32 min |
| 2025-11 | 28 | 71% | +15 min |
| 2025-12 | 30 | 60% | +26 min |
| 2026-01 | 28 | 75% | +7 min |
| 2026-02 | 11 | 73% | +4 min |
Performance by day of week
| Day | Flights | On-time |
|---|---|---|
| Mon | 31 | 55% |
| Tue | 31 | 68% |
| Wed | 33 | 58% |
| Thu | 32 | 69% |
| Fri | 31 | 55% |
| Sat | 30 | 77% |
| Sun | 30 | 63% |
Other routes
Related
Based on US Department of Transportation Bureau of Transportation Statistics on-time data. Loading live conditions and full charts…