Route reliability record
PHL→ATL
Philadelphia to Atlanta
- Flights
- 5,713
- Period
- July 2025 to June 2026
- Distance
- 666 mi
- Carriers
- 6
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 5,713 flights, of which Delta Air Lines flew 3,029 at 84.9% on time.
Delta Air Lines is the most reliable of the four carriers covered here at 84.9% on time across 3,029 flights.
Key figures
On time
79.2%
Arrivals under 15 minutes late, of 5,542 completed flights
Avg delay
66 min
Across delayed arrivals only, not all flights
Cancelled
2.73%
National rate is 1.81%
Best carrier
Delta
84.9% on time across 3,029 flights
These figures cover 5,713 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
Which airline is most reliable on PHL to ATL
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 84.9% of the time; Frontier Airlines manages 66.4%. Sample sizes sit next to every figure, because a two-point gap across 1,008 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Republic Airwaysthin sample | 156 | 90.1% | 93 min | 3.21% | A− |
| Delta Air Lines | 3,029 | 84.9% | 59 min | 2.48% | B |
| PSA Airlines | 834 | 82.1% | 68 min | 4.08% | B− |
| American Airlines | 594 | 68.3% | 70 min | 1.85% | C |
| Frontier Airlines | 1,008 | 66.4% | 71 min | 2.78% | C |
| Spirit Airlinesthin sample | 92 | 60.7% | 66 min | 3.26% | D− |
PSA Airlines cancels 4.1% 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
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 15 points, against 19 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am1,202 flights84.6%
- 8am–11am1,142 flights86.3%
- 11am–2pm879 flights77.2%
- 2pm–5pm864 flights78.8%
- 5pm–8pm1,396 flights71.7%
- 8pm–5am230 flights71.7%
Scale runs 65% to 90%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 86.3% of the time, against 71.7% for the overnight window. That is 15 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5pm–8pm window is the busiest, with 1,396 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 19 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 68.7% on time, 19 points below September, the best at 88.0%. 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. June was the busiest month here, with 544 flights.
Across the week, Wednesday is the strongest day at 86.9% on time and Sunday the weakest at 74.0%. 13 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 45% of the 76,000 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.
- 45%Late-arriving aircraft
- 27%Carrier
- 24%National Airspace System
- 3%Extreme weather
- 0%Security
45% 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 76,000 reported delay minutes here, that single category outweighs weather by 13 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 75,925 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 86.3% on time here.
Cancellations run at 2.73%, against 1.81% nationally. That is roughly one flight in 40 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.
Connections and stage length
What a delay here actually costs
7.5% 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.
The 666 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 is a different operation and performs like one: it runs 74.9% on time across 5,713 flights, 4 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 4 points of difference.
The sample behind these figures is 5,713 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. September runs 88.0% on time and July 68.7%, a swing of 19 points. If the dates move at all, move them out of July before you think about anything else. 5,542 completed flights over 12 months sit behind that.
Common questions
PHL to ATL questions
How often is PHL to ATL 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 20.8% of the 5,713 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on PHL to ATL?
Delta Air Lines leads at 84.9% on time across 3,029 flights. Frontier Airlines is at the other end on 66.4%, a gap of 19 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 PHL to ATL?
The 8am–11am departure window is the strongest at 86.3% on time. The 8pm–5am window is the weakest at 71.7%, 15 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 PHL to ATL?
July is the weakest month at 68.7% on time, compared with 88.0% in September. Across the year that is 19 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
- ATL to PHL — the return legseparate record
- Philadelphia International (PHL) delay statistics
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Republic Airways on-time record90.1%
- Delta Air Lines on-time record84.9%
- PSA Airlines on-time record82.1%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. PHL to ATL and ATL to PHL 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.