Route reliability
Seattle (SEA) to Salt Lake City (SLC): which airline is most on time?
On-time arrivals, cancellations and long delays for every airline that reported nonstop flights from Seattle, WA (SEA) to Salt Lake City, UT (SLC), September 2025 to August 2026.
Seattle, WASalt Lake City, UT
Route at a glance · September 2025 to August 2026
SEA to SLC
Seattle, WA to Salt Lake City, UT
- On time
- 82.7%vs 75.6% U.S. average Better than average
- Cancelled
- 0.8%vs 1.9% U.S. average Better than average
- 60+ min late
- 4.0%vs 8.1% U.S. average Better than average
- Scheduled flights
- 4,098in 12 months4 airlines
- Most reliable airline
- Delta Air Lines86.3% on time · 2,232 flights
On time more often than the U.S. average, with fewer cancellations.
Airlines on this route
Ranked by on-time arrival
| Airline | On time | Cancelled | 60+ min late | Avg delay when late | Diverted | Flights |
|---|---|---|---|---|---|---|
| 1. Delta Air Lines Most reliable | 86.3% | 0.5% | 4.3% | 59 min | 0.0% | 2,232 |
| 2. SkyWest Airlines Operating carrier; sold as United Express, Delta Connection, American Eagle, Alaska | 79.7% | 0.0% | 4.1% | 46 min | 0.0% | 365 |
| 3. Alaska Airlines | 78.4% | 1.3% | 3.2% | 40 min | 0.1% | 1,424 |
| 4. Frontier Airlines Small sample (under 300 flights) | 70.1% | 3.9% | 10.4% | 53 min | 0.0% | 77 |
On time = arrived within 15 minutes of schedule. Avg delay when late = average arrival delay of flights 15+ minutes late. "Most reliable" needs at least 300 flights in 12 months. Tap a heading to sort.
What this means
Delta Air Lines has the strongest record on this route.
- Delta Air Lines had the best on-time record from Seattle (SEA) to Salt Lake City (SLC): 86.3% of its 2,232 scheduled flights arrived within 15 minutes of schedule, compared with 78.4% for Alaska Airlines.
- 0.8% of flights on this route were cancelled (about 1 in 125), 1.1 points lower than the U.S. average of 1.9%.
- 4.0% of flights, about 1 in 25, arrived an hour or more late. When a flight was late (15+ minutes), the average arrival delay was 49 min.
- Overall, 82.7% of flights on this route arrived on time, 7.1 points higher than the U.S. average of 75.6%.
- Over the last 3 years, April was the most reliable month on this route (88.4% on time) and July the least reliable (75.1%).
- Flights scheduled to depart before 6 am were the most punctual (93.2% on time); flights scheduled to depart 2 pm to 3 pm were the least (73.9%).
- In the other direction, Salt Lake City (SLC) to Seattle (SEA), 79.2% of flights were on time and 0.8% were cancelled. Compare airlines SLC to SEA.
Best and worst months to fly SEA to SLC
Share of scheduled flights on time 12-month average 82.7%
Show as table
| Period | On time | Flights |
|---|---|---|
| January | 81.7% | 908 |
| February | 84.3% | 842 |
| March | 81.6% | 914 |
| April | 88.4% | 926 |
| May | 84.9% | 1,064 |
| June | 80.7% | 1,112 |
| July | 75.1% | 1,202 |
| August | 76.6% | 1,174 |
| September | 86.8% | 1,116 |
| October | 86.1% | 991 |
| November | 86.4% | 892 |
| December | 83.7% | 882 |
| Airline | Best month | Worst month |
|---|---|---|
| Delta Air Lines | April (91.2%) | July (79.6%) |
| SkyWest Airlines | October (87.7%) | August (69.0%) |
| Alaska Airlines | April (84.8%) | August (67.5%) |
Month by month, last 12 months
Share of scheduled flights on time U.S. average 75.6%
Show as table
| Period | On time | Flights |
|---|---|---|
| Sep 2025 | 88.7% | 398 |
| Oct 2025 | 84.4% | 365 |
| Nov 2025 | 85.2% | 297 |
| Dec 2025 | 76.1% | 305 |
| Jan 2026 | 82.4% | 301 |
| Feb 2026 | 83.0% | 294 |
| Mar 2026 | 81.4% | 334 |
| Apr 2026 | 92.4% | 314 |
| May 2026 | 84.9% | 338 |
| Jun 2026 | 83.8% | 359 |
| Jul 2026 | 76.4% | 411 |
| Aug 2026 | 75.1% | 382 |
Best and worst departure times
Share of scheduled flights on time
Show as table
| Period | On time | Flights |
|---|---|---|
| Departing before 6 am | 93.2% | 365 |
| Departing 7 am to 8 am | 93.0% | 388 |
| Departing 8 am to 9 am | 86.9% | 168 |
| Departing 9 am to 10 am | 87.0% | 430 |
| Departing 10 am to 11 am | Insufficient sample | 36 |
| Departing 11 am to noon | 76.9% | 635 |
| Departing noon to 1 pm | Insufficient sample | 48 |
| Departing 1 pm to 2 pm | 82.2% | 376 |
| Departing 2 pm to 3 pm | 73.9% | 134 |
| Departing 3 pm to 4 pm | 78.6% | 84 |
| Departing 4 pm to 5 pm | 79.8% | 337 |
| Departing 5 pm to 6 pm | 80.6% | 279 |
| Departing 6 pm to 7 pm | 80.3% | 274 |
| Departing 7 pm to 8 pm | 78.0% | 369 |
| Departing 8 pm to 9 pm | 75.3% | 174 |
| Departing 9 pm to 10 pm | Insufficient sample | 1 |
Sources & data dates
- Source
- U.S. DOT Bureau of Transportation Statistics, Reporting Carrier On-Time Performance (1987-present)
- Period
- September 2025 to August 2026 (12 months); month-of-year patterns September 2023 to August 2026
- Data through
- August 2026
- Processed
- 2026-11-03
- Scope
- Nonstop scheduled flights from Seattle, WA (SEA) to Salt Lake City, UT (SLC), one direction. Airlines that report to the DOT only.
- Method
- Rates use all scheduled flights as the denominator; cancelled and diverted flights count as not on time. Figures based on fewer than 50 scheduled flights are suppressed. Full methodology.