Route reliability record
JAX→DEN
Jacksonville to Denver
- Flights
- 995
- Period
- July 2025 to June 2026
- Distance
- 1,446 mi
- Carriers
- 2
This route lands a B+, 6 points better than the national rate of 77.6%. About one flight in six 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 995 JAX to DEN flights, of which United Airlines flew 617 at 88.6% on time.
Best time to fly JAX to DEN: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 93.0% of the time and Wednesday flights 90.7%, against 83.6% for the route overall.
Set against the rest of the country, this route's record is 6 points better than the US average of 77.6%. That gap is worth roughly 60 fewer late arrivals for every thousand flights.
Key figures
On time
83.6%
Arrivals under 15 minutes late, of 990 completed flights
Avg delay
71 min
Across delayed arrivals only, not all flights
Cancelled
0.20%
National rate is 1.81%
Best carrier
United
88.6% on time across 617 flights
These figures cover 995 flights between July 2025 and June 2026. The median arrival is 7 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 JAX to DEN
The choice of carrier is not cosmetic here. United Airlines arrives on time 88.6% of the time; Southwest Airlines manages 75.5%. 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 | 88.6% | 94 min | 0.16% | A+ |
| Southwest Airlines | 378 | 75.5% | 54 min | 0.26% | B+ |
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 Jacksonville to Denver
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. JAX → DENJacksonville to Denver | United Airlines | 88.5% | 88.6% | 0.16% | 8am–11am, Wed | — |
| 2. JAX → DENJacksonville to Denver | Southwest Airlines | 75.3% | 75.5% | 0.26% | 5am–8am, Wed | — |
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 53 points, against 13 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am129 flights93.0%
- 8am–11am381 flights92.4%
- 11am–2pm70 flights80.0%
- 2pm–5pm378 flights76.5%
- 5pm–8pm37 flights40.5%
- 8pm–5am—
Scale runs 30% to 100%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 40.5% on time, against 93.0% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 8am–11am window is the busiest, with 381 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 37 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 60.0% on time, 37 points below November, the best at 96.7%. 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, Wednesday is the strongest day at 90.7% on time and Sunday the weakest at 75.0%. 16 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 11,000 reported delay minutes.
- 37%Carrier
- 34%Late-arriving aircraft
- 27%National Airspace System
- 3%Extreme weather
The largest share of delay minutes, 37%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 4,270 of the 11,000 delay minutes reported here. The split is drawn from 11,479 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 93.0% on time here.
Cancellations are rare at 0.20%, below the national 1.81% 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
6.4% 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 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 76.3% on time across 995 flights, 7 points below 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 DEN 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 83.6% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 990 completed flights over 12 months sit behind that.
Common questions
JAX to DEN questions
How often is JAX to DEN delayed?
About one flight in six arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 16.4% of the 995 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on JAX to DEN?
United Airlines leads at 88.6% on time across 617 flights. Southwest Airlines is at the other end on 75.5%, 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 JAX to DEN?
The 5am–8am departure window is the strongest at 93.0% on time. The 5pm–8pm window is the weakest at 40.5%, 53 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 JAX to DEN?
June is the weakest month at 60.0% on time, compared with 96.7% in November. Across the year that is 37 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
- DEN to JAX — the return legseparate record
- Denver International (DEN) delay statistics
- United Airlines on JAX to DEN88.6%
- Southwest Airlines on JAX to DEN75.5%
- JAX to ATL, a related route84.9%
- PHX to DEN, a related route77.2%
- JAX to ORD, a related route77.3%
- United Airlines on-time record88.6%
- Southwest Airlines on-time record75.5%
- Same route, different airline: where the carrier you pick matters most
- Why the first flight of the morning is statistically safest
Direction matters. JAX to DEN and DEN to JAX 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.