Route reliability record
PHX→DEN
Phoenix to Denver
- Flights
- 9,012
- Period
- September 2025 to August 2026
- Distance
- 602 mi
- Carriers
- 6
This route lands a B+, level with the national rate of 77.3%. About one flight in four arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 9,012 PHX to DEN flights, of which United Airlines flew 2,391 at 83.3% on time.
Best time to fly PHX to DEN: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 93.0% of the time and Saturday flights 82.4%, against 76.7% for the route overall.
United Airlines is the most reliable of the four carriers covered here at 83.3% on time across 2,391 flights.
Key figures
On time
76.7%
Arrivals under 15 minutes late, of 8,927 completed flights
Avg delay
68 min
Across delayed arrivals only, not all flights
Cancelled
0.65%
National rate is 1.89%
Best carrier
United
83.3% on time across 2,391 flights
These figures cover 9,012 flights between September 2025 and August 2026. Beyond the headline rate, 8.3% 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 PHX to DEN
The choice of carrier is not cosmetic here. United Airlines arrives on time 83.3% of the time; Southwest Airlines manages 72.1%. Sample sizes sit next to every figure, because a two-point gap across 3,934 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Airthin sample | 173 | 84.3% | 39 min | 0.58% | B+ |
| United Airlines | 2,391 | 83.3% | 78 min | 0.54% | B+ |
| Frontier Airlines | 1,494 | 78.8% | 92 min | 0.74% | B+ |
| American Airlines | 987 | 74.9% | 75 min | 0.81% | C+ |
| SkyWest Airlinesthin sample | 33 | 72.7% | 104 min | 0.00% | C+ |
| Southwest Airlines | 3,934 | 72.1% | 56 min | 0.66% | C+ |
United leads Southwest by 11 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Flights on PHX to DEN
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.
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Best ways to make this trip
The most reliable ways to fly Phoenix 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. PHX → DENPhoenix to Denver | United Airlines | 82.9% | 83.3% | 0.54% | 5am–8am, Tue | UA 597 09:08 |
| 2. PHX → DENPhoenix to Denver | Frontier Airlines | 78.2% | 78.8% | 0.74% | 5am–8am, Sat | F9 1376 07:00 |
| 3. PHX → DENPhoenix to Denver | American Airlines | 74.3% | 74.9% | 0.81% | 8am–11am, Sat | — |
| 4. PHX → DENPhoenix to Denver | Southwest Airlines | 71.6% | 72.1% | 0.66% | 5am–8am, Sat | — |
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 28 points, against 11 points between the best and worst carrier.
- 5am–8am1,495 flights93.0%
- 8am–11am1,764 flights85.1%
- 11am–2pm1,691 flights78.6%
- 2pm–5pm1,953 flights65.4%
- 5pm–8pm1,369 flights67.2%
- 8pm–5am740 flights66.7%
Scale runs 55% to 100%.
Book the early departure. Flights leaving between 5am–8am arrive on time 93.0% of the time, against 65.4% for the afternoon window. That is 28 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 2pm–5pm window is the busiest, with 1,953 flights scheduled in it.
Explore
Filter PHX to DEN 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 PHX to DEN, the best departure window is 5am–8am at 93.0% on time and the worst is 2pm–5pm at 65.4%, a wide gap of 27.6 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am93.0%
- 8–11am85.1%
- 11am–2pm78.6%
- 2–5pm65.4%
- 5–8pm67.2%
- 8pm–5am66.7%
best all US flightsScale 55% to 95%.
Across the year
When delays peak on this route
This route's year swings by 21 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 64.4% on time, 21 points below April, the best at 85.7%. 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 922 flights.
Across the week, Saturday is the strongest day at 82.4% on time and Sunday the weakest at 72.8%, a spread of 10 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 47% of the 141,000 delay minutes carriers reported here, and the remaining four split what is left.
- 47%Late-arriving aircraft
- 27%National Airspace System
- 24%Carrier
- 2%Extreme weather
- 0%Security
47% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 141,000 reported delay minutes here, that single category outweighs weather by 24 to one. The split is drawn from 140,900 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 0.65%, 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
8.3% of arrivals land an hour or more late, close to the national 8.3%, so 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 602 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 runs 75.6% on time across 9,069 flights, within about a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 9,012 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
Work out the risk of missing a connection in DEN after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. April runs 85.7% on time and August 64.4%, a swing of 21 points. If the dates move at all, move them out of August before you think about anything else. 8,927 completed flights over 12 months sit behind that.
Common questions
PHX to DEN questions
How often is PHX to DEN 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 23.3% of the 9,012 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on PHX to DEN?
United Airlines leads at 83.3% on time across 2,391 flights. Southwest Airlines is at the other end on 72.1%, a gap of 11 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 PHX to DEN?
The 5am–8am departure window is the strongest at 93.0% on time. The 2pm–5pm window is the weakest at 65.4%, 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 August delays on PHX to DEN?
August is the weakest month at 64.4% on time, compared with 85.7% in April. Across the year that is 21 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 PHX — the return legseparate record
- Phoenix Sky Harbor International (PHX) delay statistics
- Denver International (DEN) delay statistics
- Envoy Air on PHX to DEN84.3%
- United Airlines on PHX to DEN83.3%
- Frontier Airlines on PHX to DEN78.8%
- American Airlines on PHX to DEN74.9%
- Southwest Airlines on PHX to DEN72.1%
- PHX to LAX, a related route82.1%
- SLC to DEN, a related route79.0%
- PHX to SEA, a related route82.2%
- Envoy Air on-time record84.3%
- United Airlines on-time record83.3%
- Frontier Airlines on-time record78.8%
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
Direction matters. PHX to DEN and DEN to PHX 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.