Best Time to Fly IAD to SLC: On-Time Stats by Hour & Airline
Washington Dulles International → Salt Lake City International
Data through July 2026 · Last updated October 18, 2026
Over the last 12 months, 82.8% of Washington (IAD) to Salt Lake City (SLC) flights arrived on time (714 scheduled flights). That is 5.2 points above the national average of 77.6%.
Among 2 airlines, Delta Air Lines led with 84.9% on time and United Airlines was last with 80.6%.
Over 24 months, Tuesday was the most reliable day (86% on time) and June the worst month (72%).
The cancellation rate was 1.4% (US average 1.8%).
IAD to SLC 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 |
|---|---|---|---|---|
| Delta Air Lines | 84.9% | 103 min | 1.6% | 364 |
| United Airlines | 80.6% | 100 min | 1.1% | 350 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly IAD to SLC
On-time arrival % by scheduled departure hour (local time), 1,305 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 6am–7am | 83.0% | 0.0% | 47 |
| 7am–8am | 87.0% | 0.9% | 682 |
| 8am–9am | 88.9% | 0.0% | 54 |
| 5pm–6pm | 77.0% | 1.1% | 522 |
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 SLC
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) | 82.8% | -1.6 pts | 0.0% | 60 |
| Summer peak (Jun 15 - Aug 15) | 77.8% | -6.6 pts | 1.3% | 233 |
| All other days | 84.4% | — | 0.9% | 992 |
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).