Best Time to Fly SLC to IAD: On-Time Stats by Hour & Airline
Salt Lake City International → Washington Dulles International
Data through July 2026 · Last updated October 18, 2026
Over the last 12 months, 86.7% of Salt Lake City (SLC) to Washington (IAD) flights arrived on time (712 scheduled flights). That is 9.1 points above the national average of 77.6%.
Among 2 airlines, United Airlines led with 89.5% on time and Delta Air Lines was last with 84.1%.
Over 24 months, Tuesday was the most reliable day (89% on time) and July the worst month (68%).
The cancellation rate was 1.5% (US average 1.8%).
SLC to IAD 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 | 89.5% | 70 min | 1.4% | 348 |
| Delta Air Lines | 84.1% | 61 min | 1.6% | 364 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly SLC to IAD
On-time arrival % by scheduled departure hour (local time), 1,302 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 7am–8am | Limited data | 21 | |
| 8am–9am | 97.1% | 2.9% | 35 |
| 9am–10am | 91.7% | 2.3% | 87 |
| 10am–11am | 89.3% | 1.2% | 161 |
| 1pm–2pm | 78.7% | 0.0% | 61 |
| 5pm–6pm | 81.9% | 0.9% | 663 |
| 6pm–7pm | 82.8% | 0.0% | 58 |
| 11pm–12am | 89.7% | 1.4% | 216 |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on SLC to IAD
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 | 20 | ||
| Christmas & New Year (Dec 20 - Jan 3) | 83.3% | -3.9 pts | 0.0% | 60 |
| Summer peak (Jun 15 - Aug 15) | 75.1% | -12.1 pts | 1.3% | 232 |
| All other days | 87.2% | — | 1.2% | 990 |
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).