Route reliability record
SEA→BNA
Seattle to Nashville
- Flights
- 1,479
- Period
- July 2025 to June 2026
- Distance
- 1,978 mi
- Carriers
- 3
This route lands a B+, about a point better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by roughly 45 minutes on average. That is a workable record, not a spotless one. That rests on 1,479 SEA to BNA flights, of which Delta Air Lines flew 511 at 84.6% on time.
Best time to fly SEA to BNA: a 8am–11am departure, ideally on a Wednesday. Flights in that window arrived on time 82.0% of the time and Wednesday flights 85.1%, against 78.6% for the route overall.
The US average over the same twelve months is 77.6%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
78.6%
Arrivals under 15 minutes late, of 1,466 completed flights
Avg delay
47 min
Across delayed arrivals only, not all flights
Cancelled
0.81%
National rate is 1.81%
Best carrier
Delta
84.6% on time across 511 flights
These figures cover 1,479 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
Which airline is most reliable on SEA to BNA
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 84.6% of the time; Alaska Airlines manages 77.0%. Sample sizes sit next to every figure, because a two-point gap across 843 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 511 | 84.6% | 61 min | 0.59% | B+ |
| Alaska Airlines | 843 | 77.0% | 43 min | 1.07% | B |
| Southwest Airlinesthin sample | 125 | 64.8% | 39 min | 0.00% | D+ |
Delta leads Alaska by 8 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Flights on SEA to BNA
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
Best ways to make this trip
The most reliable ways to fly Seattle to Nashville
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. SEA → BNASeattle to Nashville | Delta Air Lines | 84.1% | 84.6% | 0.59% | 8am–11am, Wed | DL 815 17:35 |
| 2. SEA → BNASeattle to Nashville | Alaska Airlines | 76.2% | 77.0% | 1.07% | 8pm–5am, Wed | AS 522 10:20 |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 24 points, against 8 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am5 flights—
- 8am–11am546 flights82.0%
- 11am–2pm31 flights58.1%
- 2pm–5pm14 flights—
- 5pm–8pm617 flights77.2%
- 8pm–5am266 flights76.0%
Scale runs 50% to 85%. 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 58.1% on time against 82.0% for 8am–11am. 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 617 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 28 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
August is the worst month at 64.0% on time, 28 points below April, the best at 92.4%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. July was the busiest month here, with 188 flights.
Across the week, Wednesday is the strongest day at 85.1% on time and Tuesday the weakest at 74.4%. 11 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 15,000 reported delay minutes.
- 42%Carrier
- 34%Late-arriving aircraft
- 22%National Airspace System
- 2%Extreme weather
- 0%Security
34% 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 15,000 reported delay minutes here, that single category outweighs weather by 15 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 14,817 reported delay minutes.
The largest share of delay minutes, 42%, 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 6,151 of the 15,000 delay minutes reported here.
Cancellations are rare at 0.81%, 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 actually costs
Badly late arrivals are rare here: only 4.5% 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.
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 72.7% on time across 1,479 flights, 6 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 6 points of difference.
The sample behind these figures is 1,479 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
Work out the risk of missing a connection in BNA after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. April runs 92.4% on time and August 64.0%, a swing of 28 points. If the dates move at all, move them out of August before you think about anything else. 1,466 completed flights over 12 months sit behind that.
Common questions
SEA to BNA questions
How often is SEA to BNA delayed?
About one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 21.4% of the 1,479 flights in this analysis, against 22.4% nationally. Delayed flights are late by roughly 45 minutes on average.
Which airline is most reliable on SEA to BNA?
Delta Air Lines leads at 84.6% on time across 511 flights. Alaska Airlines is at the other end on 77.0%, a gap of 8 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on SEA to BNA?
The 8am–11am departure window is the strongest at 82.0% on time. The 11am–2pm window is the weakest at 58.1%, 24 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are August delays on SEA to BNA?
August is the weakest month at 64.0% on time, compared with 92.4% in April. Across the year that is 28 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- BNA to SEA — the return legseparate record
- Seattle-Tacoma International (SEA) delay statistics
- Nashville International (BNA) delay statistics
- Delta Air Lines on SEA to BNA84.6%
- Alaska Airlines on SEA to BNA77.0%
- Southwest Airlines on SEA to BNA64.8%
- SEA to LAX, a related route83.4%
- ORD to BNA, a related route68.6%
- SEA to PHX, a related route79.2%
- Delta Air Lines on-time record84.6%
- Alaska Airlines on-time record77.0%
- Southwest Airlines on-time record64.8%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. SEA to BNA and BNA to SEA are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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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.