Washington (IAD) to Salt Lake City (SLC): On-Time Performance
Data through May 2026
Washington (IAD) to Salt Lake City (SLC) effectively runs on two schedules. In June 2024, 100% of arrivals were on time; in June 2025 that fell to 64% — a 36-point seasonal swing. Across the full period the route averages 84% on-time against a national 78%.
- On-time
- 84%
- arrived <15 min late
- Avg delay
- 14 min
- completed flights
- Cancelled
- 0.9%
- Flights/day
- 2.0
- last 12 months
- Duration
- 4h 49m
- scheduled
- Distance
- 1,827 mi
Best airline from IAD to SLC
2 airlines flew this route regularly between 2024-06 and 2026-05.
| Airline | On-time | Avg delay | Cancelled | Flights |
|---|---|---|---|---|
| Delta Air Linesmost reliable | 86% | 13 min | 1.1% | 730 |
| United Airlines | 80% | 15 min | 0.6% | 514 |
Monthly on-time trend
Best time to fly from IAD to SLC
Aim for departures around 8 a.m. (89% on-time); avoid 5 p.m. departures (79%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Mondaybest | 87% | 12 min |
| Tuesday | 86% | 17 min |
| Wednesday | 84% | 15 min |
| Thursday | 82% | 11 min |
| Friday | 84% | 18 min |
| Saturday | 83% | 12 min |
| Sunday | 80% | 12 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft20%
- Airline operations60%
- National airspace system16%
- Weather4%
Frequently asked questions
- How often are flights from IAD to SLC delayed?
- 17% of IAD–SLC flights arrived 15 or more minutes late (the US DOT definition of a delay) between 2024-06 and 2026-05. The average arrival delay across completed flights was 14 minutes.
- Which airline is most reliable from IAD to SLC?
- Delta Air Lines has the best on-time record on this route at 86%, based on 730 flights. 2 airlines flew IAD–SLC frequently enough to compare in this period.
- What is the best time of day to fly from IAD to SLC?
- Departures around 8 a.m. have the best record (89% on-time), while departures around 5 p.m. have the worst (79%). As on most US routes, delays accumulate through the day, so earlier flights are generally safer.
- How long is the flight from IAD to SLC?
- The scheduled IAD–SLC flight time averages 4h 49m over 1,827 miles. Actual arrival times vary — flights on this route land 15+ minutes late 17% of the time.
- How often are IAD to SLC flights cancelled?
- 0.9% of scheduled flights on this route were cancelled between 2024-06 and 2026-05, at or below the national rate of 1.6%.
- What is the worst month to fly from IAD to SLC?
- June 2025 was the roughest month in this dataset, with only 64% of arrivals on time. The best was June 2024 at 100%. If your dates are flexible, that 36-point gap is worth planning around.
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Based on 1,244 flights, 2024-06–2026-05. Source: US DOT Bureau of Transportation Statistics. Updated 2026-07-01.