Route reliability record
DEN→GTF
Denver to Great Falls
- Flights
- 728
- Period
- September 2025 to August 2026
- Distance
- 623 mi
- Carriers
- 2
This route lands a B+, level with the national rate of 77.3%. Roughly one flight in four arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That rests on 728 DEN to GTF flights, with a median arrival 5 minutes early.
Best time to fly DEN to GTF: a 8pm–5am departure, ideally on a Monday. Flights in that window arrived on time 94.6% of the time and Monday flights 81.1%, against 76.9% for the route overall.
The US average over the same twelve months is 77.3%, 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
76.9%
Arrivals under 15 minutes late, of 724 completed flights
Avg delay
70 min
Across delayed arrivals only, not all flights
Cancelled
0.55%
National rate is 1.89%
Best carrier
United
73.5% on time across 527 flights
These figures cover 728 flights between September 2025 and August 2026. Beyond the headline rate, 9.5% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Which airline is most reliable on DEN to GTF
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 Airlinesthin sample | 201 | 85.9% | 67 min | 1.00% | A |
| United Airlines | 527 | 73.5% | 71 min | 0.38% | C+ |
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 28 points, against half a point between the best and worst carrier.
- 5am–8am—
- 8am–11am—
- 11am–2pm365 flights83.1%
- 2pm–5pm—
- 5pm–8pm307 flights66.3%
- 8pm–5am56 flights94.6%
Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is the strongest at 94.6% on time. The full set of windows spans 28 points.
Explore
Filter DEN to GTF by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On DEN to GTF, the best departure window is 8pm–5am at 94.6% on time and the worst is 5pm–8pm at 66.3%, a wide gap of 28.3 points. All US flights leaving 8pm–5am ran 70.1%.
- 5–8am—
- 8–11am—
- 11am–2pm83.1%
- 2–5pm—
- 5–8pm66.3%
- 8pm–5am94.6%
best all US flightsScale 60% to 100%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 42 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.
June is the worst month at 53.3% on time, 42 points below November, the best at 94.9%. 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. January was the busiest month here, with 62 flights.
Across the week, Monday is the strongest day at 81.1% on time and Wednesday the weakest at 69.2%, a spread of 12 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 51% of the 12,000 delay minutes carriers reported here, and the remaining four split what is left.
- 51%Late-arriving aircraft
- 30%Carrier
- 14%National Airspace System
- 5%Extreme weather
51% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 12,000 reported delay minutes here, that single category outweighs weather by 10 to one. The split is drawn from 11,730 reported delay minutes.
Cancellations are rare at 0.55%, below the national 1.89% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here actually costs
9.5% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
The 623 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.
The return leg is a different operation and performs like one: it runs 86.1% on time across 728 flights, 9 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 9 points of difference.
One caution: this is a thin sample. 728 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 GTF after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 728 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 76.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 724 completed flights over 12 months sit behind that.
Common questions
DEN to GTF questions
How often is DEN to GTF delayed?
Roughly one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 23.1% of the 728 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
How reliable is DEN to GTF compared with the rest of the country?
76.9% of flights arrive on time here against a national 77.3%, a difference of half a point against it. That is worth a B+ on this site's grading scale.
What time of day has the fewest delays on DEN to GTF?
The 8pm–5am departure window is the strongest at 94.6% on time. The 5pm–8pm window is the weakest at 66.3%, 28 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 June delays on DEN to GTF?
June is the weakest month at 53.3% on time, compared with 94.9% in November. Across the year that is 42 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
- GTF to DEN — the return legseparate record
- Denver International (DEN) delay statistics
- SkyWest Airlines on DEN to GTF85.9%
- United Airlines on DEN to GTF73.5%
- DEN to PHX, a related route75.6%
- SLC to GTF, a related route93.4%
- DEN to SLC, a related route78.2%
- SkyWest Airlines on-time record85.9%
- United Airlines on-time record73.5%
- Why the first flight of the morning is statistically safest
- How often a connection fails at the major US hubs
Direction matters. DEN to GTF and GTF 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.