Carrier route record
WNSEA→BNA
Southwest Airlines · Seattle to Nashville
- 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 SEA to BNA draws a D+. Roughly one flight in three arrives at least 15 minutes late, and the typical late arrival is roughly 40 minutes behind schedule. Build slack into anything you connect to. That rests on 120 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 516 at 83.0% on time.
The national on-time rate over the same period is 77.3%, so Southwest on SEA to BNA runs 17 points behind the country as a whole. Across a thousand flights that is about 173 extra late arrivals.
Key figures
On time
60.0%
Arrivals under 15 minutes late, of 120 completed flights
Avg delay
39 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.89%
Whole route
80.6%
Every carrier on SEA to BNA, 1,481 flights
These figures cover 120 flights between September 2025 and August 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.
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Carrier by carrier
Southwest against every carrier on SEA to BNA
Southwest flew 120 of the 1,481 flights on SEA to BNA, about 8% of it. Its 60.0% on time is 21 points worse than the route as a whole, which runs 80.6%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from Delta at 83.0% to Southwest at 60.0%.
The two carriers here are closely matched: about a point 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 |
|---|---|---|---|---|---|
| Delta Air Lines | 516 | 83.0% | 61 min | 0.97% | B+ |
| Alaska Airlines | 845 | 82.1% | 44 min | 0.95% | B+ |
| Southwest Airlines (this page)thin sample | 120 | 60.0% | 39 min | 0.00% | D+ |
No carrier stands out. Delta tops the table at 83.0%, about a point clear of the bottom, which is inside the range this kind of sample moves year to year.
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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 19 points, against about a point between the best and worst carrier.
- 5am–8am—
- 8am–11am31 flights74.2%
- 11am–2pm—
- 2pm–5pm—
- 5pm–8pm—
- 8pm–5am89 flights55.1%
Scale runs 45% to 80%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 55.1% on time, against 74.2% 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 8pm–5am window is the busiest, with 89 flights scheduled in it.
Across the year
Southwest on SEA to BNA through the year
- Jul–Sep 202530 flights73.3%
- Oct–Dec 20251 flights—
- Apr–Jun 202627 flights—
- Jul–Sep 202662 flights59.7%
Scale runs 50% to 80%. 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 60.0% on time across 120 flights.
Split by quarter, Southwest on SEA to BNA 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 60.0% annual figure is the one to use.
Arrival by arrival
How late Southwest on SEA to BNA runs when it is late
The 48 late arrivals split 20 under half an hour, 23 between 30 and 60 minutes, and 5 an hour or more.
- 15+ min early7 flights5.8%
- Within 15 min65 flights54.2%
- 15–29 min late20 flights16.7%
- 30–59 min late23 flights19.2%
- 1–2 hours late4 flights3.3%
- 2+ hours late1 flights0.8%
Scale runs 0% to 100%.
Share of 120 completed flights by arrival against schedule.
15 of 57 late departures made up the time and arrived on time, 26% of them. In the other direction, 6 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 BNA.
The worst days
Worst days for Southwest on SEA to BNA
The latest arrival of the period was on 19 September 2025, 2 hours 45 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). Three of the five worst days fell in July 2026.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 19 September 2025 | 2 hours 45 minutes | Carrier |
| 13 July 2026 | 1 hour 58 minutes | Late-arriving aircraft |
| 7 June 2026 | 1 hour 18 minutes | Late-arriving aircraft |
| 14 July 2026 | 1 hour 4 minutes | Late-arriving aircraft |
| 5 July 2026 | 1 hour 3 minutes | Late-arriving aircraft |
Delay causes
Why Southwest runs late on this route
Late-arriving aircraft accounts for 71% of the 1,847 delay minutes carriers reported here, and the remaining four split what is left.
- 71%Late-arriving aircraft
- 18%Carrier
- 11%National Airspace System
71% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 1,847 reported delay minutes here, that single category outweighs weather by 71 to one. The split is drawn from 1,847 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 74.2% on time here.
Cancellations are rare at 0.00%, below the national 1.89% and low enough to earn the plus on the grade. Almost no flights are called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here costs
Badly late arrivals are rare here: only 4.2% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
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 38.7% on time across 120 flights, 21 points below 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 SEA to BNA
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 60.0% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 120 completed flights over 12 months sit behind that.
Related
Where to go next
- SEA to BNA, every carrier
- Southwest on BNA to SEA, the return leg
- Delta Air Lines on SEA to BNA83.0%
- Alaska Airlines on SEA to BNA82.1%
- Southwest Airlines network-wide record
- Seattle-Tacoma International (SEA) delay statistics
- Nashville International (BNA) 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.