Carrier route record

DLBOS→BNA

Delta Air Lines · Boston to Nashville

Flights: 533
Period: July 2025 to June 2026
Share of route: 18%
Carriers: 6

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

Delta on BOS to BNA sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 6 points worse than the national rate of 77.6%. The late ones land an hour and a half behind schedule. That rests on 533 flights. The strongest carrier on the route with a full sample, JetBlue Airways, flew 874 at 72.1% on time.

JetBlue Airways is the most reliable of the three carriers covered here at 72.1% on time across 874 flights.

On time

71.6%

Arrivals under 15 minutes late, of 524 completed flights

Avg delay

88 min

Across delayed arrivals only, not all flights

Cancelled

0.75%

National rate is 1.81%

Whole route

70.4%

Every carrier on BOS to BNA, 2,945 flights

These figures cover 533 flights between July 2025 and June 2026. Beyond the headline rate, 14.3% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.

Carrier by carrier

Delta against every carrier on BOS to BNA

Delta flew 533 of the 2,945 flights on BOS to BNA, about 18% of it. Its 71.6% on time is about level with the route as a whole at 70.4%. Ranked by on-time rate it is number four of six carriers on the route, where the range runs from American at 100.0% to Southwest at 67.0%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The three carriers here are closely matched: 5 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.

On-time performance by carrier on BOS to BNA
Airline	Flights	On time	Avg delay	Cancelled	Grade
American Airlinesthin sample	2	100.0%	—	0.00%	A+
Spirit Airlinesthin sample	40	86.8%	109 min	2.50%	A
JetBlue Airways	874	72.1%	64 min	2.06%	C
Delta Air Lines (this page)	533	71.6%	88 min	0.75%	C+
Republic Airways	500	71.5%	71 min	4.00%	C−
Southwest Airlines	996	67.0%	61 min	1.20%	C

Republic Airways cancels 4.0% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.

Departure window

When Delta runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 33 points, against 5 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am89 flights90.9%
8am–11am141 flights75.0%
11am–2pm1 flights—
2pm–5pm220 flights65.9%
5pm–8pm55 flights58.2%
8pm–5am27 flights—

Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 58.2% on time, against 90.9% 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 2pm–5pm window is the busiest, with 220 flights scheduled in it.

Across the year

Delta on BOS to BNA through the year

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

Delays peak in September, when the on-time rate falls to 57.1%. August is the strongest month at 83.5%. Moving a flexible trip across that boundary buys 26 points. May was the busiest month here, with 81 flights.

Across the week, Saturday is the strongest day at 81.6% on time and Friday the weakest at 64.9%. 17 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Delta runs late on this route

One category carries most of the weight here. Carrier accounts for 43% of the 13,000 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.

Carrier
43%
Late-arriving aircraft
40%
National Airspace System
14%
Extreme weather
3%

40% 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 13,000 reported delay minutes here, that single category outweighs weather by 12 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 13,036 reported delay minutes.

The largest share of delay minutes, 43%, 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 5,547 of the 13,000 delay minutes reported here.

Cancellations are rare at 0.75%, 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

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 14.3% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.

The 942 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 runs 71.5% on time across 533 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.

One caution: this is a thin sample. 533 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 Delta on BOS to BNA

Put together: treat all of this as provisional. 533 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 71.6% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 524 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