Route reliability record
DEN→HLN
Denver to Helena
- Flights
- 844
- Period
- July 2025 to June 2026
- Distance
- 594 mi
- Carriers
- 1
This route lands a B, about a point better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 844 DEN to HLN flights, with a median arrival 5 minutes early.
Best time to fly DEN to HLN: a 11am–2pm departure, ideally on a Tuesday. Flights in that window arrived on time 82.5% of the time and Tuesday flights 82.6%, against 78.9% for the route overall.
The US average over the same twelve months is 77.6%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
78.9%
Arrivals under 15 minutes late, of 830 completed flights
Avg delay
73 min
Across delayed arrivals only, not all flights
Cancelled
1.07%
National rate is 1.81%
Best carrier
SkyWest
78.9% on time across 844 flights
These figures cover 844 flights between July 2025 and June 2026. Beyond the headline rate, 8.9% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
Which airline is most reliable on DEN to HLN
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 844 | 78.9% | 73 min | 1.07% | B |
Flight by flight
Flights on DEN to HLN
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
Departure window
The best time of day to leave
Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 844 flights.
- 5am–8am—
- 8am–11am—
- 11am–2pm365 flights82.5%
- 2pm–5pm115 flights77.0%
- 5pm–8pm356 flights75.6%
- 8pm–5am8 flights—
Scale runs 65% to 90%. Rows with fewer than 30 flights show a dash.
The best window here is not the first bank but the 11am–2pm slot at 82.5% on time, ahead of 5pm–8pm at 75.6%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 11am–2pm window is the busiest, with 365 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 33 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
August is the worst month at 62.5% on time, 33 points below April, the best at 95.0%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. August was the busiest month here, with 93 flights.
Across the week, Tuesday is the strongest day at 82.6% on time and Friday the weakest at 72.0%. 11 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 13,000 reported delay minutes.
- 32%Carrier
- 28%Late-arriving aircraft
- 27%National Airspace System
- 13%Extreme weather
Extreme weather accounts for 13% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 2.2 times the usual weather exposure. The split is drawn from 12,853 reported delay minutes.
Cancellations sit at 1.07% against a national 1.81%, which is ordinary. Diversions add another 0.59%.
Connections and stage length
What a delay here actually costs
8.9% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last a little over an hour, which a normal layover absorbs.
The 594 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The return leg runs 78.9% on time across 844 flights, within half a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
One caution: this is a thin sample. 844 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
Work out the risk of missing a connection in HLN after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 844 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 78.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 830 completed flights over 12 months sit behind that.
Common questions
DEN to HLN questions
How often is DEN to HLN delayed?
About one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 21.1% of the 844 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.
How reliable is DEN to HLN compared with the rest of the country?
78.9% of flights arrive on time here against a national 77.6%, a difference of about a point in its favour. That is worth a B on this site's grading scale.
What time of day has the fewest delays on DEN to HLN?
The 11am–2pm departure window is the strongest at 82.5% on time. The 5pm–8pm window is the weakest at 75.6%, 7 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are August delays on DEN to HLN?
August is the weakest month at 62.5% on time, compared with 95.0% in April. Across the year that is 33 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- HLN to DEN — the return legseparate record
- Denver International (DEN) delay statistics
- DEN to PHX, a related route75.7%
- SLC to HLN, a related route96.4%
- DEN to SLC, a related route77.5%
- SkyWest Airlines on-time record78.9%
- Connecting flights: how much buffer the data says you need
- Worst months to fly in the US, ranked by the data
Direction matters. DEN to HLN and HLN to DEN are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.