Carrier route record

DLBUF→ATL

Delta Air Lines · Buffalo to Atlanta

Flights: 1,249
Period: July 2025 to June 2026
Share of route: 83%
Carriers: 3

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

Delta on BUF to ATL earns a B. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 6 points better than the national rate of 77.6%. When something does go wrong the average delay runs about an hour. That rests on 1,249 flights, with a median arrival 10 minutes early.

Set against the rest of the country, Delta's BUF to ATL record is 6 points better than the US average of 77.6%. That gap is worth roughly 64 fewer late arrivals for every thousand flights.

On time

84.0%

Arrivals under 15 minutes late, of 1,222 completed flights

Avg delay

60 min

Across delayed arrivals only, not all flights

Cancelled

2.00%

National rate is 1.81%

Whole route

81.5%

Every carrier on BUF to ATL, 1,507 flights

These figures cover 1,249 flights between July 2025 and June 2026. The median arrival is 10 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

Delta against every carrier on BUF to ATL

Delta flew 1,249 of the 1,507 flights on BUF to ATL, most of the route. Its 84.0% on time is 3 points better than the route as a whole, which runs 81.5%. Ranked by on-time rate it is number two of three carriers on the route, where the range runs from Southwest at 100.0% to Frontier at 68.7%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.

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 BUF to ATL
Airline	Flights	On time	Avg delay	Cancelled	Grade
Southwest Airlinesthin sample	1	100.0%	—	0.00%	A+
Delta Air Lines (this page)	1,249	84.0%	60 min	2.00%	B
Frontier Airlinesthin sample	257	68.7%	82 min	2.72%	C

Flight by flight

Delta flight numbers on BUF to ATL

Departure window

When Delta 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 1,249 flights.

5am–8am365 flights85.6%
8am–11am—
11am–2pm346 flights87.1%
2pm–5pm101 flights82.7%
5pm–8pm437 flights80.7%
8pm–5am—

Scale runs 70% to 95%. Rows with fewer than 30 flights show a dash.

The best window here is not the first bank but the 11am–2pm slot at 87.1% on time, ahead of 5pm–8pm at 80.7%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 5pm–8pm window is the busiest, with 437 flights scheduled in it.

Across the year

Delta on BUF to ATL through the year

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

December is the weak month at 75.3% on time, against 97.2% in September. 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 120 flights.

Across the week, Wednesday is the strongest day at 90.9% on time and Sunday the weakest at 76.1%. 15 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Delta runs late on this route

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 12,000 reported delay minutes.

Late-arriving aircraft
41%
Carrier
35%
National Airspace System
15%
Extreme weather
9%

41% 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 12,000 reported delay minutes here, that single category outweighs weather by 5 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 11,687 reported delay minutes.

The largest share of delay minutes, 35%, 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 4,090 of the 12,000 delay minutes reported here.

Cancellations sit at 2.00% against a national 1.81%, which is ordinary. Diversions add another 0.16%.

Connections and stage length

What a delay here costs

Badly late arrivals are rare here: only 4.4% 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 712 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 81.2% on time across 1,250 flights, within 3 points 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 1,249 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 Delta on BUF to ATL

Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 97.2% on time and December 75.3%, a swing of 22 points. If the dates move at all, move them out of December before you think about anything else. 1,222 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