Carrier route record

WNBNA→SLC

Southwest Airlines · Nashville to Salt Lake City

Flights: 272
Period: July 2025 to June 2026
Share of route: 23%
Carriers: 2

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.

Southwest on BNA to SLC 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 about an hour behind schedule. That rests on 272 flights, with a median arrival 2 minutes late.

The US average over the same twelve months is 77.6%, so there is little to separate Southwest on BNA to SLC from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

74.1%

Arrivals under 15 minutes late, of 270 completed flights

Avg delay

57 min

Across delayed arrivals only, not all flights

Cancelled

0.74%

National rate is 1.81%

Whole route

84.4%

Every carrier on BNA to SLC, 1,205 flights

These figures cover 272 flights between July 2025 and June 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.

Carrier by carrier

Southwest against every carrier on BNA to SLC

Southwest flew 272 of the 1,205 flights on BNA to SLC, about 23% of it. Its 74.1% on time is 10 points worse than the route as a whole, which runs 84.4%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from Delta at 87.5% to Southwest at 74.1%.

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.

On-time performance by carrier on BNA to SLC
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	933	87.5%	54 min	0.64%	A+
Southwest Airlines (this page)thin sample	272	74.1%	57 min	0.74%	C+

Departure window

When Southwest runs best on this route

Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 272 flights.

5am–8am—
8am–11am10 flights—
11am–2pm147 flights73.8%
2pm–5pm99 flights70.7%
5pm–8pm11 flights—
8pm–5am5 flights—

Scale runs 60% to 80%. Rows with fewer than 30 flights show a dash.

The 11am–2pm window is the strongest at 73.8% on time. The full set of windows spans 3 points.

Across the year

Southwest on BNA to SLC through the year

Jul–Sep 202592 flights76.1%
Oct–Dec 202592 flights79.3%
Jan–Mar 202650 flights85.4%
Apr–Jun 202638 flights42.1%

Scale runs 35% to 90%. 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 74.1% on time across 272 flights.

Southwest on BNA to SLC did not run the same all year. Its best quarter was Jan–Mar 2026 at 85.4% on time and its weakest Apr–Jun 2026 at 42.1%, a swing of 43 points on roughly 68 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, Friday is the strongest day at 83.3% on time and Monday the weakest at 63.9%. 19 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Southwest runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 53% of the 3,987 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.

Late-arriving aircraft
53%
Carrier
34%
National Airspace System
11%
Extreme weather
2%

53% 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 3,987 reported delay minutes here, that single category outweighs weather by 26 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 3,987 reported delay minutes.

Cancellations are rare at 0.74%, below the national 1.81% 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

7.0% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.

The 1,404 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 87.4% on time across 272 flights, 13 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 13 points of difference.

One caution: this is a thin sample. 272 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 SLC

Put together: treat all of this as provisional. 272 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 74.1% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 270 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures