PlainFlights

Route · HLN → SEA · 2020–2025 BTS data

Helena to Seattle

According to PlainFlights' route traffic ranking (BTS On-Time Performance total flights), HLN to SEA (Helena to Seattle) ranks #4743 of 4927 tracked domestic routes by total flights (most flights = #1).

Data updated 2026-06-13

84.8%
On-time
+5.8 pts
vs US avg
69 min
Delay when late
677
Flights
#4743 of 4927
Corpus placement

Cancelled

1.3%

Best Month

N/A

Worst Month

N/A

Distance

491 mi

Carriers

2

Monthly Performance

Recent 24 months of route data.

Period Flights Delayed Cancelled Diverted Carriers
Jan 2024 31 8 0 0 OO
Dec 2023 31 1 1 1 OO
Aug 2023 31 3 0 0 OO
Jul 2023 31 4 0 0 OO
Dec 2022 31 10 1 0 QX
Oct 2022 31 5 0 0 QX
Sep 2022 30 6 0 0 QX
Aug 2022 31 6 0 0 QX
Jul 2022 31 4 0 0 QX
Jun 2022 30 4 1 0 QX
May 2022 31 8 0 0 QX
Apr 2022 30 4 1 0 QX
Mar 2022 31 6 0 0 QX
Jan 2022 31 7 0 1 QX
Oct 2021 31 2 0 0 QX
Sep 2021 30 1 0 0 QX
Aug 2021 31 6 0 0 QX
Jul 2021 31 6 1 0 QX
May 2021 31 5 1 0 QX
Apr 2021 30 2 0 0 QX
Mar 2021 31 4 0 0 QX
Jan 2021 31 1 3 0 QX

HLN–SEA seasonal on-time pattern

Best: April (90.0%) · weakest: May (79.0%)

75%80%85%90%95% JanMarAprMayJunJulAugSepOctDec 82.3%

Strongest calendar month

April

90.0% on-time · ~30 flights/mo

Busiest calendar month

January

~31 flights/mo avg

Weakest calendar month

May

79.0% on-time · ~31 flights/mo

Cancellation Rate

1.3%

9 of 677 flights

Diversion Rate

0.3%

2 of 677 flights

Explore origin & destination

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

HLN - Helena

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

HLN 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 HLN and SEA side by side on delays, cancellations, and reliability.

Compare HLN vs SEA

Origin-hub reliability standing

Mid-pack among HLN departures

From HLN, this corridor sits with 2 other 75–85% on-time routes out of 3 tracked departures, not the hub's reliability leaders (1 at ≥85%) and not the softest ( 0 below 75%). Destination: Seattle · fleet on-time rank #1296 of 4927.

What the Data Says About HLN to SEA

Bureau of Transportation Statistics records show Helena to Seattle (HLN to SEA) running a 84.8% on-time rate over 677 tracked flights, on the stronger end of a typical domestic pairing. When flights do run late, the average delay is 69.0 minutes. The 491-mile corridor is served by 2 carriers, and over the last 24 months 1.3% of 677 flights were cancelled, 0.3% diverted.

Monthly performance data for this route did not show a clear best/worst split in the sample window; review the monthly table above for period-by-period detail.

On the multi-year calendar, HLN–SEA peaks in April at 90.0% on-time while January carries the heaviest traffic (~31 flights per month) ; the softest month is May at 79.0%, a 11.0-point swing that repeats because the corridor's weather and holiday mix stays stable year to year.

Frequently Asked Questions

Where does HLN to SEA rank among US routes by traffic? ▼
According to PlainFlights' route traffic ranking, HLN to SEA ranks #4743 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 HLN to SEA? ▼
Flights from Helena to Seattle have a 84.8% on-time rate based on 677 flights. The average delay is 69.0 minutes.
What is the cancellation rate for HLN to SEA? ▼
Over the last 24 months, 1.3% of flights on this route were cancelled (9 of 677 flights) and 0.3% were diverted.
How far is the flight from HLN to SEA? ▼
The flight distance from Helena (HLN) to Seattle (SEA) is approximately 491 miles. This route is served by 2 carriers.

Airports on this route

HLN Airport

Helena
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 HLN–SEA data

HLN–SEA runs 5.8 pts above the national 79% average; the remaining risk is month-to-month swing and carrier mix, not a weak headline rate.

  • Compare HLN and SEA airport profiles: delay causes and top routes differ even on the same corridor. HLN airport
  • If your dates flex, April (90.0% on-time) beats May (79.0%) on this corridor. Seasonal chart
  • 4 other routes post a similar 84.8% 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.