Route reliability record

BNA→DTW

Nashville to Detroit

Flights: 2,420
Period: July 2025 to June 2026
Distance: 456 mi
Carriers: 4

This route lands a B, 2 points better than the national rate of 77.6%. About one flight in five arrive 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 2,420 flights, of which Delta Air Lines flew 1,404 at 86.1% on time.

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.

On time

79.1%

Arrivals under 15 minutes late, of 2,390 completed flights

Avg delay

67 min

Across delayed arrivals only, not all flights

Cancelled

1.24%

National rate is 1.81%

Best carrier

Delta

86.1% on time across 1,404 flights

These figures cover 2,420 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 BNA to DTW

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 86.1% of the time; Southwest Airlines manages 68.0%. Sample sizes sit next to every figure, because a two-point gap across 846 flights means less than a ten-point one.

On-time performance by carrier on BNA to DTW
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	1,404	86.1%	99 min	1.92%	A
Spirit Airlinesthin sample	148	82.3%	71 min	0.68%	B+
Southwest Airlines	846	68.0%	44 min	0.24%	C+
SkyWest Airlinesthin sample	22	50.0%	45 min	0.00%	F+

The spread between Delta and Southwest is 18 points, wide enough that it should decide the booking. On a hundred trips that is 18 more arrivals inside the on-time window.

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 46 points, against 18 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am393 flights94.4%
8am–11am584 flights84.9%
11am–2pm282 flights79.1%
2pm–5pm355 flights80.8%
5pm–8pm686 flights70.1%
8pm–5am120 flights48.3%

Scale runs 40% to 100%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 48.3% on time, against 94.4% for the 5am–8am 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 5pm–8pm window is the busiest, with 686 flights scheduled in it.

Across the year

When delays peak on this route

This route's year swings by 22 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.

Darker means more delays. Figures are on-time percentages.August best, December worst

December is the weak month at 69.2% on time, against 91.4% in August. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. October was the busiest month here, with 233 flights.

Across the week, Wednesday is the strongest day at 84.7% on time and Sunday the weakest at 73.2%. 12 points is a smaller lever than departure hour, but it is free.

Delay causes

Why this route gets delayed

One category carries most of the weight here. Late-arriving aircraft accounts for 47% of the 33,000 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
47%
Carrier
37%
National Airspace System
13%
Extreme weather
2%
Security
0%

47% 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 33,000 reported delay minutes here, that single category outweighs weather by 22 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 33,357 reported delay minutes.

The largest share of delay minutes, 37%, 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 12,000 of the 33,000 delay minutes reported here.

Cancellations sit at 1.24% against a national 1.81%, which is ordinary. Diversions add another 0.00%.

Connections and stage length

What a delay here actually costs

5.8% 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 are the about an hour kind, which a normal layover absorbs.

At 456 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 5am–8am window matters as much as it does.

The return leg runs 78.7% on time across 2,417 flights, within half a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

The sample behind these figures is 2,420 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.

What to do with this

Booking this route

Put together: the calendar is the biggest lever here, not the carrier or the hour. August runs 91.4% on time and December 69.2%, a swing of 22 points. If the dates move at all, move them out of December before you think about anything else. 2,390 completed flights over 12 months sit behind that.

Common questions

BNA to DTW questions

How often is BNA to DTW delayed?

About one flight in five arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 20.9% of the 2,420 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.

Which airline is most reliable on BNA to DTW?

Delta Air Lines leads at 86.1% on time across 1,404 flights. Southwest Airlines is at the other end on 68.0%, a gap of 18 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 BNA to DTW?

The 5am–8am departure window is the strongest at 94.4% on time. The 8pm–5am window is the weakest at 48.3%, 46 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 December delays on BNA to DTW?

December is the weakest month at 69.2% on time, compared with 91.4% in August. Across the year that is 22 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.

Where to go next

Direction matters. BNA to DTW and DTW to BNA are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.

Key figures