Best Time to Fly IAD to STT: On-Time Stats by Hour & Airline
Washington Dulles International → Cyril E King
Data through July 2026 · Last updated October 18, 2026
Over the last 12 months, 88.0% of Washington (IAD) to Charlotte Amalie (STT) flights arrived on time (336 scheduled flights). That is 10.3 points above the national average of 77.6%.
United Airlines was the only reporting airline with regular flights on this route.
Over 24 months, Monday was the most reliable day (89% on time) and July the worst month (74%).
The cancellation rate was 1.2% (US average 1.8%).
IAD to STT on-time performance by airline
Last 12 months. Airlines with fewer than 30 completed flights are marked “limited data”.
| Airline | On time | Avg delay when late | Cancelled | Flights |
|---|---|---|---|---|
| United Airlines | 88.0% | 40 min | 1.2% | 336 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly IAD to STT
On-time arrival % by scheduled departure hour (local time), 645 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 8am–9am | 86.8% | 0.6% | 543 |
| 9am–10am | 87.1% | 0.0% | 70 |
| 12pm–1pm | 93.5% | 3.1% | 32 |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on IAD to STT
On-time arrivals during holiday periods compared with all other days, last 24 months.
| Period | On time | vs other days | Cancelled | Flights |
|---|---|---|---|---|
| Thanksgiving week (Tue before to Mon after) | Limited data | 14 | ||
| Christmas & New Year (Dec 20 - Jan 3) | 93.0% | +4.3 pts | 4.4% | 45 |
| Summer peak (Jun 15 - Aug 15) | 78.8% | -9.9 pts | 0.0% | 132 |
| All other days | 88.7% | — | 0.4% | 454 |
Monthly on-time trend
On-time arrival % each month, with the 12-month US average for reference.
What causes delays on this route
Share of reported delay minutes, last 12 months (BTS cause categories).