Route reliability record
PHX→STL
Phoenix to St. Louis
- Flights
- 2,323
- Period
- September 2025 to August 2026
- Distance
- 1,262 mi
- Carriers
- 5
This route lands a B+, about a point worse than the national rate of 77.3%. About one flight in four arrives 15 minutes late or worse, and those flights are late by roughly 55 minutes on average. That rests on 2,323 PHX to STL flights, of which American Airlines flew 584 at 77.6% on time.
Best time to fly PHX to STL: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 94.6% of the time and Wednesday flights 81.9%, against 76.2% 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
76.2%
Arrivals under 15 minutes late, of 2,302 completed flights
Avg delay
53 min
Across delayed arrivals only, not all flights
Cancelled
0.30%
National rate is 1.89%
Best carrier
American
77.6% on time across 584 flights
These figures cover 2,323 flights between September 2025 and August 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.
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Carrier by carrier
Which airline is most reliable on PHX to STL
The two carriers here are closely matched: 3 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Airthin sample | 30 | 93.3% | 77 min | 0.00% | A+ |
| SkyWest Airlinesthin sample | 24 | 87.5% | 35 min | 0.00% | A+ |
| Frontier Airlinesthin sample | 53 | 82.7% | 170 min | 1.89% | B |
| American Airlines | 584 | 77.6% | 65 min | 0.68% | B+ |
| Southwest Airlines | 1,632 | 75.1% | 47 min | 0.12% | B+ |
No carrier stands out. American tops the table at 77.6%, 3 points clear of the bottom, which is inside the range this kind of sample moves year to year.
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Best ways to make this trip
The most reliable ways to fly Phoenix to St. Louis
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 → STLPhoenix to St. Louis | American Airlines | 77.1% | 77.6% | 0.68% | 8am–11am, Tue | — |
| 2. PHX → STLPhoenix to St. Louis | Southwest Airlines | 75.0% | 75.1% | 0.12% | 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 34 points, against 3 points between the best and worst carrier.
- 5am–8am394 flights94.6%
- 8am–11am534 flights82.9%
- 11am–2pm408 flights75.5%
- 2pm–5pm333 flights64.8%
- 5pm–8pm427 flights68.9%
- 8pm–5am227 flights60.4%
Scale runs 50% to 100%.
The 8pm–5am window is where this operation falls apart: 60.4% on time, against 94.6% 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 534 flights scheduled in it.
Explore
Filter PHX to STL 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 STL, the best departure window is 5am–8am at 94.6% on time and the worst is 8pm–5am at 60.4%, a wide gap of 34.2 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am94.6%
- 8–11am82.9%
- 11am–2pm75.5%
- 2–5pm64.8%
- 5–8pm68.9%
- 8pm–5am60.4%
best all US flightsScale 50% to 100%.
Across the year
When delays peak on this route
This route's year swings by 22 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.
July is the worst month at 63.3% on time, 22 points below February, the best at 84.9%. 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. March was the busiest month here, with 234 flights.
Across the week, Wednesday is the strongest day at 81.9% on time and Sunday the weakest at 71.4%, a spread of 11 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 50% of the 29,000 delay minutes carriers reported here, and the remaining four split what is left.
- 50%Late-arriving aircraft
- 40%Carrier
- 7%National Airspace System
- 2%Extreme weather
- 1%Security
50% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 29,000 reported delay minutes here, that single category outweighs weather by 33 to one. The split is drawn from 28,993 reported delay minutes.
The largest share of delay minutes, 40%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 12,000 of the 29,000 delay minutes reported 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
6.3% 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 roughly 55 minutes, which a normal layover absorbs.
The 1,262 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 74.8% on time across 2,309 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 2,323 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 STL 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. February runs 84.9% on time and July 63.3%, a swing of 22 points. If the dates move at all, move them out of July before you think about anything else. 2,302 completed flights over 12 months sit behind that.
Common questions
PHX to STL questions
How often is PHX to STL 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 23.8% of the 2,323 flights in this analysis, against 22.7% nationally. Delayed flights are late by roughly 55 minutes on average.
Which airline is most reliable on PHX to STL?
American Airlines leads at 77.6% on time across 584 flights. Southwest Airlines is at the other end on 75.1%, a gap of 3 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 STL?
The 5am–8am departure window is the strongest at 94.6% on time. The 8pm–5am window is the weakest at 60.4%, 34 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 July delays on PHX to STL?
July is the weakest month at 63.3% on time, compared with 84.9% in February. Across the year that is 22 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
- STL to PHX — the return legseparate record
- Phoenix Sky Harbor International (PHX) delay statistics
- St. Louis Lambert International (STL) delay statistics
- American Airlines on PHX to STL77.6%
- Southwest Airlines on PHX to STL75.1%
- PHX to DEN, a related route76.7%
- DEN to STL, a related route77.7%
- PHX to LAX, a related route82.1%
- Envoy Air on-time record93.3%
- SkyWest Airlines on-time record87.5%
- Frontier Airlines on-time record82.7%
- 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. PHX to STL and STL 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.