Carrier route record
AAMIA→SEA
American Airlines · Miami to Seattle
- Flights
- 475
- Period
- September 2025 to August 2026
- Share of route
- 39%
- Carriers
- 3
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with American Airlines.
American on MIA to SEA sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 5 points worse than the national rate of 77.3%. The late ones land roughly 50 minutes behind schedule. That rests on 475 flights. The strongest carrier on the route with a full sample, Alaska Airlines, flew 392 at 69.1% on time.
The national on-time rate over the same period is 77.3%, so American on MIA to SEA runs 5 points behind the country as a whole. Across a thousand flights that is about 48 extra late arrivals.
Key figures
On time
72.5%
Arrivals under 15 minutes late, of 472 completed flights
Avg delay
52 min
Across delayed arrivals only, not all flights
Cancelled
0.42%
National rate is 1.89%
Whole route
68.7%
Every carrier on MIA to SEA, 1,233 flights
These figures cover 475 flights between September 2025 and August 2026. Beyond the headline rate, 9.1% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
American against every carrier on MIA to SEA
American flew 475 of the 1,233 flights on MIA to SEA, about 39% of it. Its 72.5% on time is 4 points better than the route as a whole, which runs 68.7%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from American at 72.5% to Delta at 63.4%.
The two carriers here are closely matched: 6 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 |
|---|---|---|---|---|---|
| American Airlines (this page) | 475 | 72.5% | 52 min | 0.42% | C+ |
| Alaska Airlines | 392 | 69.1% | 48 min | 1.28% | C |
| Delta Air Lines | 366 | 63.4% | 90 min | 1.64% | D |
No carrier stands out. Alaska tops the table at 69.1%, 6 points clear of the bottom, which is inside the range this kind of sample moves year to year.
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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 22 points, against 6 points between the best and worst carrier.
- 5am–8am5 flights—
- 8am–11am105 flights88.5%
- 11am–2pm—
- 2pm–5pm—
- 5pm–8pm155 flights66.7%
- 8pm–5am210 flights68.1%
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 88.5% of the time, against 66.7% for the evening window. That is 22 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 210 flights scheduled in it.
Across the year
American on MIA to SEA through the year
January is the weak month at 51.5% on time, against 94.2% in August. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. July was the busiest month here, with 62 flights.
Across the week, Wednesday is the strongest day at 78.8% on time and Sunday the weakest at 67.6%, a spread of 11 points.
Arrival by arrival
How late American on MIA to SEA runs when it is late
American on MIA to SEA often beats the schedule: 154 of 472 completed flights, 33%, arrived 15 minutes or more early. The 130 late arrivals split 49 under half an hour, 38 between 30 and 60 minutes, and 43 an hour or more.
- 15+ min early154 flights32.6%
- Within 15 min188 flights39.8%
- 15–29 min late49 flights10.4%
- 30–59 min late38 flights8.1%
- 1–2 hours late33 flights7.0%
- 2+ hours late10 flights2.1%
Scale runs 0% to 100%.
Share of 472 completed flights by arrival against schedule.
27 of 115 late departures made up the time and arrived on time, 23% of them. In the other direction, 42 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at SEA.
The worst days
Worst days for American on MIA to SEA
The latest arrival of the period was on 15 March 2026, 3 hours 17 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 15 March 2026 | 3 hours 17 minutes | Late-arriving aircraft |
| 25 January 2026 | 3 hours 12 minutes | Late-arriving aircraft |
| 6 February 2026 | 3 hours | Carrier |
| 26 June 2026 | 2 hours 54 minutes | Carrier |
| 2 February 2026 | 2 hours 39 minutes | Late-arriving aircraft |
Delay causes
Why American runs late on this route
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 6,788 reported delay minutes.
- 36%Late-arriving aircraft
- 36%Carrier
- 24%National Airspace System
- 3%Extreme weather
- 2%Security
36% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 6,788 reported delay minutes here, that single category outweighs weather by 14 to one. The split is drawn from 6,788 reported delay minutes.
The largest share of delay minutes, 36%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 2,416 of the 6,788 delay minutes reported here.
Cancellations are rare at 0.42%, 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 costs
9.1% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
At 2,724 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 78.4% on time across 475 flights, 6 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 6 points of difference.
One caution: this is a thin sample. 475 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 SEA
Put together: treat all of this as provisional. 475 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 72.5% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 472 completed flights over 12 months sit behind that.
Related
Where to go next
- MIA to SEA, every carrier
- American on SEA to MIA, the return leg
- Alaska Airlines on MIA to SEA69.1%
- Delta Air Lines on MIA to SEA63.4%
- American Airlines network-wide record
- Miami International (MIA) delay statistics
- Seattle-Tacoma International (SEA) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
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.