Carrier route record
AAMIA→STL
American Airlines · Miami to St. Louis
- Flights
- 603
- Period
- July 2025 to June 2026
- Share of route
- 53%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with American Airlines.
American on MIA to STL 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 a little over an hour behind schedule. That rests on 603 flights, with a median arrival 6 minutes early.
The US average over the same twelve months is 77.6%, so there is little to separate American on MIA to STL from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
73.8%
Arrivals under 15 minutes late, of 595 completed flights
Avg delay
73 min
Across delayed arrivals only, not all flights
Cancelled
1.00%
National rate is 1.81%
Whole route
72.4%
Every carrier on MIA to STL, 1,141 flights
These figures cover 603 flights between July 2025 and June 2026. Beyond the headline rate, 10.8% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
American against every carrier on MIA to STL
American flew 603 of the 1,141 flights on MIA to STL, most of the route. Its 73.8% on time is about level with the route as a whole at 72.4%. Ranked by on-time rate it is number three of four carriers on the route, where the range runs from Envoy at 89.2% to Southwest at 66.9%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
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 |
|---|---|---|---|---|---|
| Envoy Airthin sample | 93 | 89.2% | 47 min | 0.00% | A+ |
| Republic Airwaysthin sample | 4 | 75.0% | 196 min | 0.00% | B+ |
| American Airlines (this page) | 603 | 73.8% | 73 min | 1.00% | C |
| Southwest Airlines | 441 | 66.9% | 60 min | 0.45% | C+ |
Departure window
When American runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 21 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–8am17 flights—
- 8am–11am103 flights88.2%
- 11am–2pm—
- 2pm–5pm118 flights79.1%
- 5pm–8pm—
- 8pm–5am365 flights66.8%
Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 88.2% of the time, against 66.8% for the overnight window. That is 21 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8pm–5am window is the busiest, with 365 flights scheduled in it.
Across the year
American on MIA to STL through the year
August is the worst month at 38.7% on time, 51 points below November, the best at 90.0%. 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 89 flights.
Across the week, Wednesday is the strongest day at 83.3% on time and Sunday the weakest at 58.8%. 25 points is a smaller lever than departure hour, but it is free.
Delay causes
Why American runs late on this route
One category carries most of the weight here. Carrier accounts for 45% of the 11,000 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.
- 45%Carrier
- 45%Late-arriving aircraft
- 7%National Airspace System
- 3%Extreme weather
45% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 11,000 reported delay minutes here, that single category outweighs weather by 16 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 11,383 reported delay minutes.
The largest share of delay minutes, 45%, 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 5,156 of the 11,000 delay minutes reported here.
Cancellations sit at 1.00% against a national 1.81%, which is ordinary. Diversions add another 0.33%.
Connections and stage length
What a delay here costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.8% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
The 1,068 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 88.6% on time across 605 flights, 15 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 15 points of difference.
One caution: this is a thin sample. 603 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.
What to do with this
Booking American on MIA to STL
Put together: treat all of this as provisional. 603 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 73.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 595 completed flights over 12 months sit behind that.
Related
Where to go next
- MIA to STL, every carrier
- American on STL to MIA, the return leg
- Southwest Airlines on MIA to STL66.9%
- American Airlines network-wide record
- Miami International (MIA) delay statistics
- St. Louis Lambert International (STL) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
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.