Route reliability record
STL→LAX
St. Louis to Los Angeles
- Flights
- 1,028
- Period
- July 2025 to June 2026
- Distance
- 1,592 mi
- Carriers
- 2
This route sits in the middle of the pack with a C+. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 1,028 STL to LAX flights, with a median arrival 2 minutes late.
Best time to fly STL to LAX: a 8am–11am departure, ideally on a Tuesday. Flights in that window arrived on time 84.6% of the time and Tuesday flights 83.1%, against 74.0% 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
74.0%
Arrivals under 15 minutes late, of 1,025 completed flights
Avg delay
64 min
Across delayed arrivals only, not all flights
Cancelled
0.19%
National rate is 1.81%
Best carrier
Southwest
73.4% on time across 674 flights
These figures cover 1,028 flights between July 2025 and June 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.
Carrier by carrier
Which airline is most reliable on STL to LAX
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 |
|---|---|---|---|---|---|
| SkyWest Airlinesthin sample | 354 | 75.3% | 92 min | 0.56% | B+ |
| Southwest Airlines | 674 | 73.4% | 50 min | 0.00% | C+ |
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 40 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am452 flights78.9%
- 8am–11am240 flights84.6%
- 11am–2pm17 flights—
- 2pm–5pm56 flights64.3%
- 5pm–8pm104 flights76.7%
- 8pm–5am159 flights44.7%
Scale runs 35% to 90%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 44.7% on time, against 84.6% for the 8am–11am 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 5am–8am window is the busiest, with 452 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 32 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.
September is the best month on the calendar at 86.6% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. December was the busiest month here, with 103 flights.
Across the week, Tuesday is the strongest day at 83.1% on time and Monday the weakest at 60.4%. 23 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. Carrier accounts for 56% of the 17,000 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.
- 56%Carrier
- 27%Late-arriving aircraft
- 10%National Airspace System
- 7%Extreme weather
- 0%Security
The largest share of delay minutes, 56%, 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 9,491 of the 17,000 delay minutes reported here. The split is drawn from 16,831 reported delay minutes.
Cancellations are rare at 0.19%, 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
6.5% 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.
At 1,592 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg is a different operation and performs like one: it runs 77.0% on time across 1,028 flights, 3 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 3 points of difference.
One caution: this is a thin sample. 1,028 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 LAX after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 1,028 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 74.0% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,025 completed flights over 12 months sit behind that.
Common questions
STL to LAX questions
How often is STL to LAX 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 26.0% of the 1,028 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
How reliable is STL to LAX compared with the rest of the country?
74.0% of flights arrive on time here against a national 77.6%, a difference of 4 points against it. That is worth a C+ on this site's grading scale.
What time of day has the fewest delays on STL to LAX?
The 8am–11am departure window is the strongest at 84.6% on time. The 8pm–5am window is the weakest at 44.7%, 40 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 April delays on STL to LAX?
April is the weakest month at 54.2% on time, compared with 86.6% in September. Across the year that is 32 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
- LAX to STL — the return legseparate record
- St. Louis Lambert International (STL) delay statistics
- Los Angeles International (LAX) delay statistics
- SkyWest Airlines on STL to LAX75.3%
- Southwest Airlines on STL to LAX73.4%
- STL to ATL, a related route85.3%
- SFO to LAX, a related route73.9%
- STL to DEN, a related route74.9%
- SkyWest Airlines on-time record75.3%
- Southwest Airlines on-time record73.4%
- The best time of day to fly, according to 7.04 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. STL to LAX and LAX to STL 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.