PlainFlights

Route · SEA → MSO · 2020–2025 BTS data

Seattle to Missoula

According to PlainFlights' route traffic ranking (BTS On-Time Performance total flights), SEA to MSO (Seattle to Missoula) ranks #3331 of 4927 tracked domestic routes by total flights (most flights = #1).

Data updated 2026-06-13

82.2%
On-time
+3.2 pts
vs US avg
51 min
Delay when late
2,929
Flights
#3331 of 4927
Corpus placement

Cancelled

1.1%

Best Month

Oct 2022 97%

Worst Month

Dec 2022 68%

Distance

389 mi

Carriers

2

Monthly Performance

Recent 24 months of route data.

Period Flights Delayed Cancelled Diverted Carriers
Dec 2025 62 12 0 0 AS
Nov 2025 59 10 2 0 AS
Oct 2025 37 5 0 0 AS
Aug 2025 31 14 0 0 AS
Jul 2025 31 11 0 1 AS
Jun 2025 30 10 0 0 AS
May 2025 31 18 0 0 AS
Apr 2025 30 12 0 0 AS
Jan 2025 31 15 1 0 AS
Oct 2024 31 12 0 0 AS
Aug 2024 31 14 0 0 AS
Jul 2024 31 10 0 0 AS
Jun 2024 30 12 0 0 AS
Dec 2022 101 32 12 0 QX
Nov 2022 106 19 0 0 QX
Oct 2022 119 4 0 0 QX
Sep 2022 138 17 0 1 QX
Aug 2022 93 14 0 0 QX
Jul 2022 93 17 0 0 QX
Jun 2022 90 18 0 0 QX
May 2022 93 19 0 0 QX
Apr 2022 60 8 0 1 QX
Mar 2022 77 10 0 0 QX
Feb 2022 84 13 1 0 QX

SEA–MSO seasonal on-time pattern

Best: March (91.0%) · weakest: December (73.4%)

70%75%80%85%90%95% JanFebMarAprMayJunJulAugSepOctNovDec 73.4%

Strongest calendar month

March

91.0% on-time · ~101 flights/mo

Busiest calendar month

September

~129 flights/mo avg

Weakest calendar month

December

73.4% on-time · ~85 flights/mo

Cancellation Rate

1.1%

16 of 1,519 flights

Diversion Rate

0.2%

3 of 1,519 flights

Explore origin & destination

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

SEA - Seattle

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

SEA on-time profile

MSO - Missoula

Full on-time, delay-cause, and seasonal performance for Missoula, MT.

MSO on-time profile

Compare the two airports

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

Compare SEA vs MSO

Origin-hub reliability standing

Mid-pack among SEA departures

From SEA, this corridor sits with 63 other 75–85% on-time routes out of 89 tracked departures, not the hub's reliability leaders (25 at ≥85%) and not the softest ( 1 below 75%). Destination: Missoula · fleet on-time rank #2282 of 4927.

What the Data Says About SEA to MSO

Bureau of Transportation Statistics records show Seattle to Missoula (SEA to MSO) running a 82.2% on-time rate over 2,929 tracked flights, on the stronger end of a typical domestic pairing. When flights do run late, the average delay is 50.8 minutes. The 389-mile corridor is served by 2 carriers, and over the last 24 months 1.1% of 1,519 flights were cancelled, 0.2% diverted.

The monthly split is wide on this route: Oct 2022 posted the strongest performance at 97% on-time, while Dec 2022 came in at just 68% - a 28-point swing worth factoring into travel timing.

On the multi-year calendar, SEA–MSO peaks in March at 91.0% on-time while September carries the heaviest traffic (~129 flights per month) ; the softest month is December at 73.4%, a 17.6-point swing that repeats because the corridor's weather and holiday mix stays stable year to year.

Frequently Asked Questions

Where does SEA to MSO rank among US routes by traffic? ▼
According to PlainFlights' route traffic ranking, SEA to MSO ranks #3331 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 SEA to MSO? ▼
Flights from Seattle to Missoula have a 82.2% on-time rate based on 2,929 flights. The average delay is 50.8 minutes. The best recent month was Oct 2022 with 97% on-time.
What is the cancellation rate for SEA to MSO? ▼
Over the last 24 months, 1.1% of flights on this route were cancelled (16 of 1,519 flights) and 0.2% were diverted.
How far is the flight from SEA to MSO? ▼
The flight distance from Seattle (SEA) to Missoula (MSO) is approximately 389 miles. This route is served by 2 carriers.
When is the best time to fly from SEA to MSO? ▼
The best recent month for on-time performance was Oct 2022 (97% on-time). The worst was Dec 2022 (68% on-time). Consider booking during months with historically better performance.

Airports on this route

SEA Airport

Seattle
MSO Airport

Missoula
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 SEA–MSO data

SEA–MSO runs 3.2 pts above the national 79% average; the remaining risk is month-to-month swing and carrier mix, not a weak headline rate.

  • Compare SEA and MSO airport profiles: delay causes and top routes differ even on the same corridor. SEA airport
  • If your dates flex, March (91.0% on-time) beats December (73.4%) on this corridor. Seasonal chart
  • 4 other routes post a similar 82.2% 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.