Airline on-time record

DL

Delta Air Lines

Flights: 1,038,570
Period: July 2025 to June 2026
Airports: 25
US rank: #2 by volume

Delta Air Lines lands a B, 4 points better than the national rate of 77.6%. Roughly one flight in five arrive 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 1,038,570 flights, of which Phoenix (PHX) flew 10,668 at 86.9% on time.

Phoenix (PHX) is the most reliable of the 25 airports covered here at 86.9% on time across 10,668 flights.

On time

81.6%

National average is 77.6%

Avg delay

71 min

Across delayed flights only

Cancelled

1.62%

National rate is 1.81%

Largest base

ATL

240,801 departures, 80.0% on time

These figures cover 1.04 million flights between July 2025 and June 2026. The median arrival is 8 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.

Airport by airport

Where Delta Air Lines runs well, and where it does not

The choice of airport is not cosmetic here. Phoenix (PHX) arrives on time 86.9% of the time; Chicago (ORD) manages 73.3%. Sample sizes sit next to every figure, because a two-point gap across 10,543 flights means less than a ten-point one.

Delta Air Lines on-time performance by departure airport
Airport	Flights	On time	Avg delay	Cancelled	Grade
ATL · Atlanta	240,801	80.0%	59 min	1.60%	B
MSP · Minneapolis	64,966	79.2%	62 min	1.09%	B
DTW · Detroit	60,319	77.9%	66 min	1.34%	B
SLC · Salt Lake City	54,634	83.8%	62 min	0.74%	B+
LAX · Los Angeles	37,285	81.6%	68 min	1.06%	B
SEA · Seattle	32,257	81.5%	65 min	1.05%	B
JFK · New York	30,722	77.9%	71 min	2.51%	B
LGA · New York	29,662	74.9%	77 min	3.79%	C−
BOS · Boston	26,419	76.8%	73 min	2.03%	B
MCO · Orlando	21,416	78.0%	83 min	1.85%	B
LAS · Las Vegas	15,755	85.6%	77 min	1.00%	A
TPA · Tampa	13,993	80.8%	78 min	1.64%	B
SFO · San Francisco	13,817	78.7%	68 min	1.19%	B
AUS · Austin	13,055	82.3%	81 min	1.42%	B
FLL · Fort Lauderdale	12,884	77.2%	78 min	2.12%	B
RDU · Raleigh	12,031	85.1%	80 min	1.63%	A
DFW · Dallas-Fort Worth	11,747	80.9%	92 min	2.49%	B
MIA · Miami	11,625	74.1%	78 min	2.10%	C
DEN · Denver	11,579	83.1%	77 min	1.33%	B
PHX · Phoenix	10,668	86.9%	86 min	1.03%	A
ORD · Chicago	10,543	73.3%	91 min	2.68%	C
SAN · San Diego	9,577	86.8%	76 min	1.13%	A
DCA · Washington	9,505	78.7%	90 min	2.54%	B
BNA · Nashville	9,316	84.9%	81 min	1.74%	B
IAH · Houston	8,369	80.8%	83 min	1.78%	B

New York (LGA) cancels 3.8% 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.

Route by route

Busiest Delta Air Lines routes

These are the 25 routes Delta Air Lines flies most often, each against its network-wide 81.6%. Route-level variation inside a single airline is routinely wider than the gap between two airlines nationally.

Busiest Delta Air Lines routes by flight volume
Route	Flights	On time	Avg delay	Cancelled	Grade
ATL to MCO	5,465	70.7%	64 min	1.17%	C
MCO to ATL	5,463	79.1%	88 min	1.24%	B
ATL to LGA	4,936	76.7%	66 min	2.96%	B
LGA to ATL	4,933	79.9%	73 min	2.98%	B
ATL to TPA	4,413	74.6%	55 min	1.18%	C
TPA to ATL	4,413	81.7%	75 min	1.22%	B
ATL to FLL	4,272	73.5%	55 min	1.57%	C
FLL to ATL	4,268	78.9%	74 min	1.66%	B
ATL to LAX	3,849	79.6%	55 min	0.75%	B+
LAX to ATL	3,844	81.5%	64 min	0.86%	B+
DCA to ATL	3,838	80.9%	88 min	2.81%	B
ATL to DCA	3,838	67.3%	60 min	2.58%	C
JAX to ATL	3,830	86.4%	84 min	1.49%	A
ATL to JAX	3,829	76.3%	57 min	1.44%	B
RDU to ATL	3,800	89.5%	86 min	1.37%	A
ATL to RDU	3,799	83.2%	56 min	1.24%	B
PBI to ATL	3,737	84.0%	63 min	1.53%	B
ATL to PBI	3,737	76.3%	52 min	1.53%	B
DTW to ATL	3,703	81.6%	68 min	0.49%	B+
ATL to DTW	3,698	79.5%	57 min	0.51%	B+
ATL to BOS	3,666	76.2%	59 min	1.72%	B
BOS to ATL	3,662	82.1%	75 min	1.77%	B
ATL to BNA	3,361	82.0%	56 min	1.90%	B
BNA to ATL	3,360	87.1%	72 min	2.02%	A
LAX to JFK	3,358	81.6%	93 min	1.79%	B

Departure window

The best time of day to fly Delta Air Lines

Departure time matters more here than the choice of airport. The gap between the best and worst window is 16 points, against 14 points between the best and worst airport. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am182,702 flights90.3%
8am–11am179,486 flights86.4%
11am–2pm189,557 flights82.7%
2pm–5pm176,975 flights77.5%
5pm–8pm168,068 flights74.7%
8pm–5am141,782 flights76.3%

Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 90.3% of the time, against 74.7% for the evening window. That is 16 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 189,557 flights scheduled in it.

Across the year

Delta Air Lines through the calendar

Delta's year swings by 13 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.September best, December worst

December is the weak month at 74.5% on time, against 87.6% 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. July was the busiest month here, with 94,066 flights.

Across the week, Wednesday is the strongest day at 84.8% on time and Sunday the weakest at 77.4%. 7 points is a smaller lever than departure hour, but it is free.

Delay causes

What holds Delta Air Lines up

One category carries most of the weight here. Carrier accounts for 45% of the 13.3 million 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
45%
Late-arriving aircraft
30%
National Airspace System
21%
Extreme weather
4%
Security
0%

The largest share of delay minutes, 45%, 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 airports on the same schedule is genuinely earned. It accounts for 5.97 million of the 13.3 million delay minutes reported here. The split is drawn from 13,332,051 reported delay minutes.

The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 90.3% on time here.

Cancellations sit at 1.62% against a national 1.81%, which is ordinary. Diversions add another 0.26%.

6.4% 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 a little over an hour kind, which a normal layover absorbs.

1,038,570 flights sit behind these numbers, which is a large enough sample that the headline rate is not moving on noise. Where a sub-group falls below 30 flights the site shows a dash instead of a percentage.

What to do with this

Booking Delta Air Lines

Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 87.6% on time and December 74.5%, a swing of 13 points. If the dates move at all, move them out of December before you think about anything else. 1,019,043 completed flights over 12 months sit behind that.

Common questions

Delta Air Lines reliability questions

How often is Delta Air Lines delayed?

Roughly 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 18.4% of the 1,038,570 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.

Which airport does Delta Air Lines run best from?

Phoenix (PHX) leads at 86.9% on time across 10,668 flights. Chicago (ORD) is at the other end on 73.3%, a gap of 14 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 Delta Air Lines?

The 5am–8am departure window is the strongest at 90.3% on time. The 5pm–8pm window is the weakest at 74.7%, 16 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 Delta Air Lines?

December is the weakest month at 74.5% on time, compared with 87.6% in September. Across the year that is 13 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

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