Route reliability record
COS→PHX
Colorado Springs to Phoenix
- Flights
- 1,003
- Period
- September 2025 to August 2026
- Distance
- 551 mi
- Carriers
- 1
This route lands a B+, 4 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 1,003 COS to PHX flights, with a median arrival 7 minutes early.
Best time to fly COS to PHX: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 96.6% of the time and Saturday flights 89.2%, against 81.3% for the route overall.
Set against the rest of the country, this route's record is 4 points better than the US average of 77.3%. That gap is worth roughly 40 fewer late arrivals for every thousand flights.
Key figures
On time
81.3%
Arrivals under 15 minutes late, of 998 completed flights
Avg delay
56 min
Across delayed arrivals only, not all flights
Cancelled
0.30%
National rate is 1.89%
Best carrier
Southwest
81.3% on time across 1,003 flights
These figures cover 1,003 flights between September 2025 and August 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.
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Carrier by carrier
Which airline is most reliable on COS to PHX
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 |
|---|---|---|---|---|---|
| Southwest Airlines | 1,003 | 81.3% | 56 min | 0.30% | B+ |
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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 32 points, against half a point between the best and worst carrier.
- 5am–8am323 flights96.6%
- 8am–11am58 flights84.5%
- 11am–2pm220 flights80.8%
- 2pm–5pm101 flights64.4%
- 5pm–8pm204 flights69.5%
- 8pm–5am97 flights71.9%
Scale runs 55% to 100%.
Book the early departure. Flights leaving between 5am–8am arrive on time 96.6% of the time, against 64.4% for the afternoon window. That is 32 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 323 flights scheduled in it.
Explore
Filter COS to PHX 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 COS to PHX, the best departure window is 5am–8am at 96.6% on time and the worst is 2pm–5pm at 64.4%, a wide gap of 32.2 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am96.6%
- 8–11am84.5%
- 11am–2pm80.8%
- 2–5pm64.4%
- 5–8pm69.5%
- 8pm–5am71.9%
best all US flightsScale 55% to 100%.
Across the year
When delays peak on this route
This route's year swings by 27 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 68.6% on time, 27 points below March, the best at 95.6%. 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 91 flights.
Across the week, Saturday is the strongest day at 89.2% on time and Friday the weakest at 77.3%, a spread of 12 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 62% of the 11,000 delay minutes carriers reported here, and the remaining four split what is left.
- 62%Late-arriving aircraft
- 19%National Airspace System
- 17%Carrier
- 3%Extreme weather
62% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 11,000 reported delay minutes here, that single category outweighs weather by 23 to one. The split is drawn from 10,542 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 96.6% on time here.
Cancellations are rare at 0.30%, 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
6.1% 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 551 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 73.6% on time across 1,003 flights, 8 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 8 points of difference.
One caution: this is a thin sample. 1,003 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 PHX after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 1,003 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 81.3% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 998 completed flights over 12 months sit behind that.
Common questions
COS to PHX questions
How often is COS to PHX 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 18.7% of the 1,003 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
How reliable is COS to PHX compared with the rest of the country?
81.3% of flights arrive on time here against a national 77.3%, a difference of 4 points in its favour. That is worth a B+ on this site's grading scale.
What time of day has the fewest delays on COS to PHX?
The 5am–8am departure window is the strongest at 96.6% on time. The 2pm–5pm window is the weakest at 64.4%, 32 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 COS to PHX?
June is the weakest month at 68.6% on time, compared with 95.6% in March. Across the year that is 27 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
- PHX to COS — the return legseparate record
- Phoenix Sky Harbor International (PHX) delay statistics
- COS to DEN, a related route81.4%
- DEN to PHX, a related route75.6%
- COS to DFW, a related route77.9%
- Southwest Airlines on-time record81.3%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Direction matters. COS to PHX and PHX to COS 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.