Airline on-time record
DL
Delta Air Lines
- Flights
- 1,039,517
- Period
- September 2025 to August 2026
- Airports
- 25
- US rank
- #2 by volume
Delta Air Lines lands a B, 4 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That rests on 1,039,517 flights, of which San Diego (SAN) flew 9,581 at 86.3% on time.
San Diego (SAN) is the most reliable of the 25 airports covered here at 86.3% on time across 9,581 flights.
Key figures
On time
81.1%
National average is 77.3%
Avg delay
71 min
Across delayed flights only
Cancelled
1.74%
National rate is 1.89%
Largest base
ATL
240,917 departures, 79.5% on time
These figures cover 1.04 million flights between September 2025 and August 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. San Diego (SAN) arrives on time 86.3% of the time; Chicago (ORD) manages 72.0%. Sample sizes sit next to every figure, because a two-point gap across 10,687 flights means less than a ten-point one.
| Airport | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| ATL · Atlanta | 240,917 | 79.5% | 59 min | 1.67% | B |
| MSP · Minneapolis | 64,705 | 79.4% | 61 min | 1.19% | B |
| DTW · Detroit | 60,378 | 77.8% | 65 min | 1.48% | B |
| SLC · Salt Lake City | 54,749 | 83.2% | 60 min | 0.80% | B+ |
| LAX · Los Angeles | 37,561 | 80.9% | 68 min | 1.16% | B |
| SEA · Seattle | 32,382 | 80.7% | 64 min | 1.11% | B |
| JFK · New York | 30,645 | 76.5% | 71 min | 3.01% | B− |
| LGA · New York | 29,531 | 74.0% | 78 min | 4.28% | C− |
| BOS · Boston | 26,567 | 76.0% | 73 min | 2.16% | B |
| MCO · Orlando | 21,571 | 77.9% | 83 min | 1.94% | B |
| LAS · Las Vegas | 15,583 | 84.4% | 79 min | 1.08% | B |
| TPA · Tampa | 14,082 | 80.6% | 79 min | 1.75% | B |
| SFO · San Francisco | 13,973 | 75.8% | 67 min | 1.29% | B |
| AUS · Austin | 13,200 | 82.6% | 79 min | 1.52% | B |
| FLL · Fort Lauderdale | 12,987 | 76.7% | 74 min | 2.29% | B |
| RDU · Raleigh | 11,943 | 84.7% | 80 min | 1.72% | B |
| MIA · Miami | 11,676 | 74.7% | 78 min | 2.21% | C |
| DFW · Dallas-Fort Worth | 11,632 | 81.4% | 88 min | 2.59% | B |
| DEN · Denver | 11,497 | 83.1% | 75 min | 1.37% | B |
| ORD · Chicago | 10,687 | 72.0% | 91 min | 3.13% | C− |
| PHX · Phoenix | 10,637 | 86.1% | 86 min | 1.14% | A |
| SAN · San Diego | 9,581 | 86.3% | 79 min | 1.17% | A |
| DCA · Washington | 9,579 | 77.9% | 88 min | 2.47% | B |
| BNA · Nashville | 9,366 | 83.6% | 79 min | 1.83% | B |
| IAH · Houston | 8,429 | 81.0% | 83 min | 1.90% | B |
New York (LGA) cancels 4.3% 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 81.1%. Route-level variation inside a single airline is routinely wider than the gap between two airlines nationally.
| Route | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| ATL to MCO | 5,534 | 70.5% | 65 min | 1.32% | C |
| MCO to ATL | 5,531 | 78.3% | 88 min | 1.39% | B |
| ATL to LGA | 4,937 | 75.9% | 66 min | 3.48% | B− |
| LGA to ATL | 4,935 | 79.1% | 73 min | 3.55% | B− |
| ATL to TPA | 4,452 | 74.3% | 59 min | 1.33% | C |
| TPA to ATL | 4,451 | 81.4% | 80 min | 1.39% | B |
| ATL to FLL | 4,383 | 73.9% | 57 min | 1.78% | C |
| FLL to ATL | 4,379 | 78.5% | 73 min | 1.92% | B |
| ATL to DCA | 3,850 | 66.7% | 60 min | 2.44% | C |
| DCA to ATL | 3,850 | 79.2% | 88 min | 2.55% | B |
| JAX to ATL | 3,846 | 85.9% | 80 min | 1.64% | A |
| ATL to JAX | 3,845 | 76.4% | 56 min | 1.59% | B |
| ATL to LAX | 3,817 | 79.1% | 57 min | 0.73% | B+ |
| RDU to ATL | 3,812 | 88.3% | 82 min | 1.50% | A |
| ATL to RDU | 3,811 | 82.9% | 58 min | 1.34% | B |
| LAX to ATL | 3,811 | 80.8% | 66 min | 0.84% | B+ |
| DTW to ATL | 3,780 | 81.2% | 68 min | 0.48% | B+ |
| ATL to DTW | 3,774 | 77.9% | 60 min | 0.50% | B+ |
| ATL to BOS | 3,731 | 74.4% | 61 min | 1.82% | C |
| BOS to ATL | 3,726 | 80.8% | 75 min | 1.85% | B |
| PBI to ATL | 3,402 | 83.6% | 64 min | 1.59% | B |
| ATL to PBI | 3,402 | 76.4% | 52 min | 1.62% | B |
| BHM to ATL | 3,371 | 87.2% | 83 min | 1.72% | A |
| ATL to BHM | 3,371 | 83.1% | 64 min | 1.69% | B |
| ATL to BNA | 3,369 | 80.6% | 56 min | 1.90% | B |
Flight by flight
Busiest Delta Air Lines flight numbers
Delta Air Lines has 1,599 flight numbers that flew one route often enough to report a rate. These are the busiest; the full list is one click away.
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.
- 5am–8am182,385 flights90.0%
- 8am–11am180,705 flights86.1%
- 11am–2pm189,633 flights82.1%
- 2pm–5pm178,430 flights76.6%
- 5pm–8pm168,590 flights74.0%
- 8pm–5am139,774 flights76.1%
Scale runs 65% to 95%.
Book the early departure. Flights leaving between 5am–8am arrive on time 90.0% of the time, against 74.0% 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 189,633 flights scheduled in it.
Across the year
Delta Air Lines through the calendar
Delta's year swings by 14 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.
July is the worst month at 74.1% on time, 14 points below September, the best at 87.6%. 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 94,140 flights.
Across the week, Wednesday is the strongest day at 85.3% on time and Sunday the weakest at 76.5%, a spread of 9 points.
Delay causes
What holds Delta Air Lines up
Carrier accounts for 44% of the 13.7 million delay minutes carriers reported here, and the remaining four split what is left.
- 44%Carrier
- 29%Late-arriving aircraft
- 22%National Airspace System
- 4%Extreme weather
- 0%Security
The largest share of delay minutes, 44%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 6.04 million of the 13.7 million delay minutes reported here. The split is drawn from 13,694,845 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 90.0% on time here.
Cancellations sit at 1.74% against a national 1.89%, which is ordinary. Diversions add another 0.27%.
6.7% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last a little over an hour, which a normal layover absorbs.
1,039,517 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 July 74.1%, a swing of 14 points. If the dates move at all, move them out of July before you think about anything else. 1,018,714 completed flights over 12 months sit behind that.
Common questions
Delta Air Lines reliability questions
How often is Delta Air Lines 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 18.9% of the 1,039,517 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
Which airport does Delta Air Lines run best from?
San Diego (SAN) leads at 86.3% on time across 9,581 flights. Chicago (ORD) is at the other end on 72.0%, 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 90.0% on time. The 5pm–8pm window is the weakest at 74.0%, 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 July delays on Delta Air Lines?
July is the weakest month at 74.1% on time, compared with 87.6% in September. Across the year that is 14 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
- Delta Air Lines at ATL — Atlanta79.5%
- Delta Air Lines at MSP — Minneapolis79.4%
- Delta Air Lines at DTW — Detroit77.8%
- Delta Air Lines at SLC — Salt Lake City83.2%
- Delta Air Lines at LAX — Los Angeles80.9%
- ATL to MCO route record70.5%
- MCO to ATL route record78.3%
- ATL to LGA route record75.9%
- LGA to ATL route record79.1%
- US airline on-time rankings: 14 carriers, four measures
- The best time of day to fly, according to 7.05 million flight records
Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.