Route reliability record
DEN→JAX
Denver to Jacksonville
- Flights
- 995
- Period
- July 2025 to June 2026
- Distance
- 1,446 mi
- Carriers
- 2
This route lands a B+, about a point worse than the national rate of 77.6%. About one flight in four arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 995 DEN to JAX flights, of which United Airlines flew 617 at 81.2% on time.
Best time to fly DEN to JAX: a 8am–11am departure, ideally on a Friday. Flights in that window arrived on time 87.1% of the time and Friday flights 80.4%, against 76.3% 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
76.3%
Arrivals under 15 minutes late, of 993 completed flights
Avg delay
57 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.81%
Best carrier
United
81.2% on time across 617 flights
These figures cover 995 flights between July 2025 and June 2026. The median arrival is 2 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
Carrier by carrier
Which airline is most reliable on DEN to JAX
The choice of carrier is not cosmetic here. United Airlines arrives on time 81.2% of the time; Southwest Airlines manages 68.4%. Sample sizes sit next to every figure, because a two-point gap across 378 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 617 | 81.2% | 63 min | 0.00% | B+ |
| Southwest Airlines | 378 | 68.4% | 51 min | 0.00% | C+ |
The spread between United and Southwest is 13 points, wide enough that it should decide the booking. On a hundred trips that is 13 more arrivals inside the on-time window.
Best ways to make this trip
The most reliable ways to fly Denver to Jacksonville
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. DEN → JAXDenver to Jacksonville | United Airlines | 81.2% | 81.2% | 0.00% | 8am–11am, Wed | — |
| 2. DEN → JAXDenver to Jacksonville | Southwest Airlines | 68.4% | 68.4% | 0.00% | 2pm–5pm, Fri | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
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 21 points, against 13 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am—
- 8am–11am287 flights87.1%
- 11am–2pm143 flights65.7%
- 2pm–5pm362 flights78.4%
- 5pm–8pm198 flights66.7%
- 8pm–5am5 flights—
Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.
The weak window here is the middle of the day, not the evening: 11am–2pm runs 65.7% on time against 87.1% for 8am–11am. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 2pm–5pm window is the busiest, with 362 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 40 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 54.8% on time, 40 points below November, the best at 94.5%. 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. March was the busiest month here, with 95 flights.
Across the week, Friday is the strongest day at 80.4% on time and Thursday the weakest at 72.5%. 8 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Late-arriving aircraft accounts for 46% of the 13,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 46%Late-arriving aircraft
- 31%Carrier
- 22%National Airspace System
- 2%Extreme weather
46% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 13,000 reported delay minutes here, that single category outweighs weather by 27 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 13,295 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 87.1% on time here.
Cancellations are rare at 0.00%, below the national 1.81% and low enough to earn the plus on the grade. Almost no flights are called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here actually costs
6.3% 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 about an hour, which a normal layover absorbs.
The 1,446 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 is a different operation and performs like one: it runs 83.6% on time across 995 flights, 7 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 7 points of difference.
One caution: this is a thin sample. 995 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 JAX after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 995 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 76.3% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 993 completed flights over 12 months sit behind that.
Common questions
DEN to JAX questions
How often is DEN to JAX delayed?
About 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 23.7% of the 995 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on DEN to JAX?
United Airlines leads at 81.2% on time across 617 flights. Southwest Airlines is at the other end on 68.4%, a gap of 13 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on DEN to JAX?
The 8am–11am departure window is the strongest at 87.1% on time. The 11am–2pm window is the weakest at 65.7%, 21 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 JAX?
August is the weakest month at 54.8% on time, compared with 94.5% in November. Across the year that is 40 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
- JAX to DEN — the return legseparate record
- Denver International (DEN) delay statistics
- United Airlines on DEN to JAX81.2%
- Southwest Airlines on DEN to JAX68.4%
- DEN to PHX, a related route75.7%
- ATL to JAX, a related route75.5%
- DEN to SLC, a related route77.5%
- United Airlines on-time record81.2%
- Southwest Airlines on-time record68.4%
- Same route, different airline: where the carrier you pick matters most
- Why the first flight of the morning is statistically safest
Direction matters. DEN to JAX and JAX 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.