Flight OddsUA521 IAH → BOS
United Airlines · Houston, TX to Boston, MA · 98 flights observed, 2026-03-05 to 2026-06-30 · 1,597 mi
UA521 covers more than one route in the data window — the stats below are for IAH → BOS, the one it has flown most recently. The others are linked under “Other routes”.
On-time arrival
69%
Median delay
-2 min
90th percentile
+61 min
Cancellation rate
0%
How often is UA521 on time?
Across 98 flights on IAH → BOS from 2026-03-05 to 2026-06-30, UA521 arrived within 15 minutes of schedule 69% of the time. The median arrival delay was -2 min, and the worst 10% of flights arrived +61 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 | 68 | 69% |
| 16-30 min | 13 | 13% |
| 31-60 min | 7 | 7% |
| 61-120 min | 4 | 4% |
| 2+ hrs | 6 | 6% |
Performance by month
| Month | Flights | On-time | Avg delay |
|---|---|---|---|
| 2026-03 | 24 | 67% | +28 min |
| 2026-04 | 30 | 70% | +5 min |
| 2026-05 | 26 | 81% | -2 min |
| 2026-06 | 18 | 56% | +18 min |
Performance by day of week
| Day | Flights | On-time |
|---|---|---|
| Mon | 12 | 75% |
| Tue | 9 | 89% |
| Wed | 16 | 63% |
| Thu | 17 | 76% |
| Fri | 17 | 71% |
| Sat | 11 | 64% |
| Sun | 16 | 56% |
Other routes
Related
Based on US Department of Transportation Bureau of Transportation Statistics on-time data. Loading live conditions and full charts…