Carrier route record
WNBNA→SFO
Southwest Airlines · Nashville to San Francisco
- Flights
- 312
- Period
- September 2025 to August 2026
- Share of route
- 27%
- Carriers
- 2
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on BNA to SFO earns an F+, which is as low as this site's scale goes for a reason. Only 49.2% of flights arrive inside the 15-minute window, 28 points worse than the national rate of 77.3%. Late arrivals average about an hour. Treat any tight connection here as a coin flip. That rests on 312 flights, with a median arrival 16 minutes late.
The national on-time rate over the same period is 77.3%, so Southwest on BNA to SFO runs 28 points behind the country as a whole. Across a thousand flights that is about 281 extra late arrivals.
Key figures
On time
49.2%
Arrivals under 15 minutes late, of 309 completed flights
Avg delay
58 min
Across delayed arrivals only, not all flights
Cancelled
0.64%
National rate is 1.89%
Whole route
67.9%
Every carrier on BNA to SFO, 1,174 flights
These figures cover 312 flights between September 2025 and August 2026. Beyond the headline rate, 17.5% 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 SFO
Southwest flew 312 of the 1,174 flights on BNA to SFO, about 27% of it. Its 49.2% on time is 19 points worse than the route as a whole, which runs 67.9%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from United at 74.6% to Southwest at 49.2%.
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 |
|---|---|---|---|---|---|
| United Airlines | 862 | 74.6% | 58 min | 0.70% | C+ |
| Southwest Airlines (this page)thin sample | 312 | 49.2% | 58 min | 0.64% | F+ |
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
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 32 points, against half a point between the best and worst carrier.
- 5am–8am—
- 8am–11am11 flights—
- 11am–2pm121 flights63.9%
- 2pm–5pm81 flights44.4%
- 5pm–8pm98 flights31.6%
- 8pm–5am1 flights—
Scale runs 25% to 70%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 31.6% on time, against 63.9% for the 11am–2pm 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 11am–2pm window is the busiest, with 121 flights scheduled in it.
Across the year
Southwest on BNA to SFO through the year
- Jul–Sep 202530 flights73.3%
- Oct–Dec 202568 flights61.2%
- Jan–Mar 202661 flights78.0%
- Apr–Jun 202691 flights24.2%
- Jul–Sep 202662 flights33.9%
Scale runs 15% to 85%.
Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 49.2% on time across 312 flights.
Southwest on BNA to SFO did not run the same all year. Its best quarter was Jan–Mar 2026 at 78.0% on time and its weakest Apr–Jun 2026 at 24.2%, a swing of 54 points on roughly 62 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.
Across the week, Tuesday is the strongest day at 63.2% on time and Thursday the weakest at 39.5%, a spread of 24 points.
Arrival by arrival
How late Southwest on BNA to SFO runs when it is late
The 157 late arrivals split 37 under half an hour, 66 between 30 and 60 minutes, and 54 an hour or more.
- 15+ min early27 flights8.7%
- Within 15 min125 flights40.5%
- 15–29 min late37 flights12.0%
- 30–59 min late66 flights21.4%
- 1–2 hours late42 flights13.6%
- 2+ hours late12 flights3.9%
Scale runs 0% to 100%.
Share of 309 completed flights by arrival against schedule.
38 of 189 late departures made up the time and arrived on time, 20% of them. Only 6 left on time and still arrived late.
The worst days
Worst days for Southwest on BNA to SFO
The latest arrival of the period was on 8 July 2026, 7 hours 14 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 8 July 2026 | 7 hours 14 minutes | Carrier |
| 3 July 2026 | 3 hours 25 minutes | Late-arriving aircraft |
| 1 August 2026 | 3 hours 25 minutes | Late-arriving aircraft |
| 21 May 2026 | 2 hours 57 minutes | Carrier |
| 15 April 2026 | 2 hours 36 minutes | Carrier |
Delay causes
Why Southwest runs late on this route
Late-arriving aircraft accounts for 42% of the 9,129 delay minutes carriers reported here, and the remaining four split what is left.
- 42%Late-arriving aircraft
- 29%National Airspace System
- 27%Carrier
- 1%Extreme weather
42% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 9,129 reported delay minutes here, that single category outweighs weather by 38 to one. The split is drawn from 9,129 reported delay minutes.
Cancellations are rare at 0.64%, 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
17.5% 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 1,969 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 58.4% on time across 312 flights, 9 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 9 points of difference.
One caution: this is a thin sample. 312 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 SFO
Put together: treat all of this as provisional. 312 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 49.2% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 309 completed flights over 12 months sit behind that.
Related
Where to go next
- BNA to SFO, every carrier
- Southwest on SFO to BNA, the return leg
- United Airlines on BNA to SFO74.6%
- Southwest Airlines network-wide record
- Nashville International (BNA) delay statistics
- San Francisco International (SFO) delay statistics
- Why the first flight of the morning is statistically safest
- How often a connection fails at the major US hubs
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.