Carrier route record
WNBNA→SEA
Southwest Airlines · Nashville to Seattle
- Flights
- 120
- Period
- September 2025 to August 2026
- Share of route
- 8%
- Carriers
- 3
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on BNA to SEA earns an F+, which is as low as this site's scale goes for a reason. Only 38.7% of flights arrive inside the 15-minute window, 39 points worse than the national rate of 77.3%. Late arrivals average about 50 minutes. Treat any tight connection here as a coin flip. That rests on 120 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 516 at 79.8% on time.
The national on-time rate over the same period is 77.3%, so Southwest on BNA to SEA runs 39 points behind the country as a whole. Across a thousand flights that is about 386 extra late arrivals.
Key figures
On time
38.7%
Arrivals under 15 minutes late, of 119 completed flights
Avg delay
50 min
Across delayed arrivals only, not all flights
Cancelled
0.83%
National rate is 1.89%
Whole route
72.4%
Every carrier on BNA to SEA, 1,481 flights
These figures cover 120 flights between September 2025 and August 2026. Beyond the headline rate, 16.8% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Southwest against every carrier on BNA to SEA
Southwest flew 120 of the 1,481 flights on BNA to SEA, about 8% of it. Its 38.7% on time is 34 points worse than the route as a whole, which runs 72.4%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from Delta at 79.8% to Southwest at 38.7%.
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 79.8% of the time; Alaska Airlines manages 72.7%. Sample sizes sit next to every figure, because a two-point gap across 845 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 516 | 79.8% | 60 min | 1.16% | B |
| Alaska Airlines | 845 | 72.7% | 44 min | 1.18% | C |
| Southwest Airlines (this page)thin sample | 120 | 38.7% | 50 min | 0.83% | F+ |
Delta leads Alaska by 7 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
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Departure window
When Southwest runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 25 points, against 7 points between the best and worst carrier.
- 5am–8am—
- 8am–11am—
- 11am–2pm34 flights20.6%
- 2pm–5pm35 flights45.7%
- 5pm–8pm51 flights46.0%
- 8pm–5am—
Scale runs 10% to 50%. Rows with fewer than 30 flights show a dash.
The weak window here is the middle of the day, not the evening: 11am–2pm runs 20.6% on time against 46.0% for 5pm–8pm. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 5pm–8pm window is the busiest, with 51 flights scheduled in it.
Across the year
Southwest on BNA to SEA through the year
- Jul–Sep 202530 flights56.7%
- Oct–Dec 20251 flights—
- Apr–Jun 202627 flights—
- Jul–Sep 202662 flights35.5%
Scale runs 25% to 60%. Rows with fewer than 30 flights show a dash.
Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 38.7% on time across 120 flights.
Split by quarter, Southwest on BNA to SEA logged 30 flights in Jul–Sep 2025, 1 flights in Oct–Dec 2025, 27 flights in Apr–Jun 2026 and 62 flights in Jul–Sep 2026. Fewer than three of those quarters carried the 30 completed flights this site needs before printing a rate, so the 38.7% annual figure is the one to use.
Arrival by arrival
How late Southwest on BNA to SEA runs when it is late
The 73 late arrivals split 30 under half an hour, 23 between 30 and 60 minutes, and 20 an hour or more.
- 15+ min early9 flights7.6%
- Within 15 min37 flights31.1%
- 15–29 min late30 flights25.2%
- 30–59 min late23 flights19.3%
- 1–2 hours late14 flights11.8%
- 2+ hours late6 flights5.0%
Scale runs 0% to 100%.
Share of 119 completed flights by arrival against schedule.
12 of 71 late departures made up the time and arrived on time, 17% of them. In the other direction, 14 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 Southwest on BNA to SEA
The latest arrival of the period was on 2 August 2026, 2 hours 48 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). Four of the five worst days fell in June 2026.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 2 August 2026 | 2 hours 48 minutes | Carrier |
| 13 June 2026 | 2 hours 47 minutes | Carrier |
| 29 June 2026 | 2 hours 40 minutes | Carrier |
| 23 June 2026 | 2 hours 26 minutes | Late-arriving aircraft |
| 27 June 2026 | 2 hours 4 minutes | Late-arriving aircraft |
Delay causes
Why Southwest runs late on this route
Late-arriving aircraft accounts for 44% of the 3,616 delay minutes carriers reported here, and the remaining four split what is left.
- 44%Late-arriving aircraft
- 33%Carrier
- 19%National Airspace System
- 4%Extreme weather
44% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 3,616 reported delay minutes here, that single category outweighs weather by 12 to one. The split is drawn from 3,616 reported delay minutes.
Cancellations are rare at 0.83%, 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
16.8% 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 1,978 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 60.0% on time across 120 flights, 21 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 21 points of difference.
One caution: this is a thin sample. 120 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 Southwest on BNA to SEA
Put together: treat all of this as provisional. 120 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 38.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 119 completed flights over 12 months sit behind that.
Related
Where to go next
- BNA to SEA, every carrier
- Southwest on SEA to BNA, the return leg
- Delta Air Lines on BNA to SEA79.8%
- Alaska Airlines on BNA to SEA72.7%
- Southwest Airlines network-wide record
- Nashville International (BNA) 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.