Carrier route record

WNSLC→BNA

Southwest Airlines · Salt Lake City to Nashville

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 SLC to BNA earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 10 points better than the national rate of 77.6%. When something does go wrong the average delay runs roughly 45 minutes. That rests on 272 flights, with a median arrival 6 minutes early.

Set against the rest of the country, Southwest's SLC to BNA record is 10 points better than the US average of 77.6%. That gap is worth roughly 98 fewer late arrivals for every thousand flights.

On time

87.4%

Arrivals under 15 minutes late, of 270 completed flights

Avg delay

47 min

Across delayed arrivals only, not all flights

Cancelled

0.74%

National rate is 1.81%

Whole route

85.8%

Every carrier on SLC to BNA, 1,205 flights

These figures cover 272 flights between July 2025 and June 2026. The median arrival is 6 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.

Carrier by carrier

Southwest against every carrier on SLC to BNA

Southwest flew 272 of the 1,205 flights on SLC to BNA, about 23% of it. Its 87.4% on time is 2 points better than the route as a whole, which runs 85.8%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from Southwest at 87.4% to Delta at 85.4%.

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 SLC to BNA
Airline	Flights	On time	Avg delay	Cancelled	Grade
Southwest Airlines (this page)thin sample	272	87.4%	47 min	0.74%	A+
Delta Air Lines	933	85.4%	52 min	0.54%	A+

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–8am13 flights—
8am–11am83 flights86.6%
11am–2pm162 flights88.8%
2pm–5pm14 flights—
5pm–8pm—
8pm–5am—

Scale runs 80% to 95%. Rows with fewer than 30 flights show a dash.

The 11am–2pm window is the strongest at 88.8% on time. The full set of windows spans 2 points.

Across the year

Southwest on SLC to BNA through the year

Jul–Sep 202592 flights82.6%
Oct–Dec 202592 flights87.0%
Jan–Mar 202650 flights97.9%
Apr–Jun 202638 flights86.8%

Scale runs 75% to 100%. 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 87.4% on time across 272 flights.

Southwest on SLC to BNA did not run the same all year. Its best quarter was Jan–Mar 2026 at 97.9% on time and its weakest Jul–Sep 2025 at 82.6%, a swing of 15 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, Monday is the strongest day at 94.4% on time and Sunday the weakest at 75.6%. 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. Carrier accounts for 44% of the 1,586 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.

Carrier
44%
Late-arriving aircraft
29%
National Airspace System
19%
Extreme weather
8%

The largest share of delay minutes, 44%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 696 of the 1,586 delay minutes reported here. The split is drawn from 1,586 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

Badly late arrivals are rare here: only 2.2% land an hour or more behind schedule, against 8.1% 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.

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 74.1% on time across 272 flights, 13 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 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 SLC to BNA

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 87.4% 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