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Route · SLC → SEA · 2020–2025 BTS data

Salt Lake City to Seattle

According to PlainFlights' route traffic ranking (BTS On-Time Performance total flights), SLC to SEA (Salt Lake City to Seattle) ranks #260 of 4927 tracked domestic routes by total flights (most flights = #1).

Data updated 2026-06-13

84%
On-time
+5 pts
vs US avg
59 min
Delay when late
22,741
Flights
#260 of 4927
Corpus placement

Cancelled

0.8%

Best Month

Oct 2024 91%

Worst Month

Jun 2025 67%

Distance

689 mi

Carriers

21

Monthly Performance

Recent 24 months of route data.

Period Flights Delayed Cancelled Diverted Carriers
Dec 2025 303 88 1 2 DL,F9,AS,OO
Nov 2025 299 48 9 1 OO,DL,F9,AS
Oct 2025 367 74 5 0 AS,OO,DL,F9
Sep 2025 398 71 1 1 OO,DL,F9,AS
Aug 2025 409 113 5 0 OO,F9,AS,DL
Jul 2025 394 101 4 0 AS,OO,DL,F9
Jun 2025 373 123 2 0 AS,OO,DL,F9
May 2025 360 93 1 1 AS,OO,DL,F9
Apr 2025 307 53 1 0 DL,F9,OO,AS
Mar 2025 306 52 1 2 AS,OO,DL,F9
Feb 2025 281 46 3 0 AS,OO,DL,F9
Jan 2025 319 54 0 2 AS,OO,DL,F9
Dec 2024 304 37 0 0 AS,DL,F9,OO
Nov 2024 317 32 2 1 OO,AS,DL,F9
Oct 2024 335 29 1 1 AS,OO,DL,F9
Sep 2024 367 56 0 0 OO,AS,DL
Aug 2024 383 108 2 1 AS,DL,OO
Jul 2024 397 113 10 0 AS,DL,OO
Jun 2024 382 102 0 0 AS,DL,OO
May 2024 364 69 0 0 AS,DL,OO
Apr 2024 306 40 0 0 AS,DL,OO
Mar 2024 275 38 1 0 AS,DL,OO
Feb 2024 269 30 0 1 AS,DL,OO
Jan 2024 286 73 14 1 AS,DL,OO

SLC–SEA seasonal on-time pattern

Best: October (88.5%) · weakest: June (78.8%)

75%80%85%90% JanFebMarAprMayJunJulAugSepOctNovDec 80.7%

Strongest calendar month

October

88.5% on-time · ~319 flights/mo

Busiest calendar month

August

~361 flights/mo avg

Weakest calendar month

June

78.8% on-time · ~323 flights/mo

Cancellation Rate

0.8%

63 of 8,101 flights

Diversion Rate

0.2%

14 of 8,101 flights

Explore origin & destination

On-time and delay data for the airports this route connects.

SLC - Salt Lake City

Full on-time, delay-cause, and seasonal performance for Salt Lake City, UT.

SLC on-time profile

SEA - Seattle

Full on-time, delay-cause, and seasonal performance for Seattle, WA.

SEA on-time profile

Compare the two airports

See SLC and SEA side by side on delays, cancellations, and reliability.

Compare SLC vs SEA

Origin-hub reliability standing

Mid-pack among SLC departures

From SLC, this corridor sits with 31 other 75–85% on-time routes out of 85 tracked departures, not the hub's reliability leaders (54 at ≥85%) and not the softest ( 0 below 75%). Destination: Seattle · fleet on-time rank #1593 of 4927.

What the Data Says About SLC to SEA

Bureau of Transportation Statistics records show Salt Lake City to Seattle (SLC to SEA) running a 84% on-time rate over 22,741 tracked flights, on the stronger end of a typical domestic pairing. When flights do run late, the average delay is 59.0 minutes. The 689-mile corridor is served by 21 carriers, and over the last 24 months 0.8% of 8,101 flights were cancelled, 0.2% diverted.

The monthly split is wide on this route: Oct 2024 posted the strongest performance at 91% on-time, while Jun 2025 came in at just 67% - a 24-point swing worth factoring into travel timing.

On the multi-year calendar, SLC–SEA peaks in October at 88.5% on-time while August carries the heaviest traffic (~361 flights per month) ; the softest month is June at 78.8%, a 9.7-point swing that repeats because the corridor's weather and holiday mix stays stable year to year.

Frequently Asked Questions

Where does SLC to SEA rank among US routes by traffic? ▼
According to PlainFlights' route traffic ranking, SLC to SEA ranks #260 of 4927 tracked domestic routes by total flights (most flights = #1). That ordinal matches our busiest-routes listing (total_flights DESC). See /methodology#corpus-placement for the exact sort basis.
How often are flights delayed from SLC to SEA? ▼
Flights from Salt Lake City to Seattle have a 84% on-time rate based on 22,741 flights. The average delay is 59.0 minutes. The best recent month was Oct 2024 with 91% on-time.
What is the cancellation rate for SLC to SEA? ▼
Over the last 24 months, 0.8% of flights on this route were cancelled (63 of 8,101 flights) and 0.2% were diverted.
How far is the flight from SLC to SEA? ▼
The flight distance from Salt Lake City (SLC) to Seattle (SEA) is approximately 689 miles. This route is served by 21 carriers.
When is the best time to fly from SLC to SEA? ▼
The best recent month for on-time performance was Oct 2024 (91% on-time). The worst was Jun 2025 (67% on-time). Consider booking during months with historically better performance.

Airports on this route

SLC Airport

Salt Lake City
SEA Airport

Seattle
Data source

Data Source: Bureau of Transportation Statistics (BTS), On-Time Performance Data. Statistics reflect cumulative performance across all available reporting periods.

Read our methodology - how this data is sourced, computed, and verified.

Using SLC–SEA data

SLC–SEA runs 5 pts above the national 79% average; the remaining risk is month-to-month swing and carrier mix, not a weak headline rate.

  • Compare SLC and SEA airport profiles: delay causes and top routes differ even on the same corridor. SLC airport
  • If your dates flex, October (88.5% on-time) beats June (78.8%) on this corridor. Seasonal chart
  • 4 other routes post a similar 84% on-time rate; compare before you commit to this pairing. Similar routes

On-time rate reflects the BTS historical average across all reporting carriers on this origin–destination pair, not any single flight or booking recommendation.

Data sourced from U.S. Department of Transportation Bureau of Transportation Statistics (BTS) On-Time Performance data. See our methodology for details. Retrieved and formatted by PlainFlights

Every figure on PlainFlights is rendered directly from BTS On-Time Performance data, no number is typed in by an editor. This page aggregates this specific route's on-time performance and monthly trend, live from the dataset. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.