Route reliability record

ATL→PHL

Atlanta to Philadelphia

Flights: 5,683
Period: June 2025 to May 2026
Distance: 666 mi
Carriers: 6

This route sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 5 points worse than the national rate of 77.4%. The late ones land a little over an hour behind schedule. That rests on 5,683 flights, of which PSA Airlines flew 872 at 80.9% on time.

PSA Airlines is the most reliable of the four carriers covered here at 80.9% on time across 872 flights.

On time

72.9%

Arrivals under 15 minutes late, of 5,508 completed flights

Avg delay

74 min

Across delayed arrivals only, not all flights

Cancelled

2.96%

National rate is 1.80%

Best carrier

PSA

80.9% on time across 872 flights

These figures cover 5,683 flights between June 2025 and May 2026. Beyond the headline rate, 10.1% 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

Which airline is most reliable on ATL to PHL

The choice of carrier is not cosmetic here. PSA Airlines arrives on time 80.9% of the time; Frontier Airlines manages 60.4%. Sample sizes sit next to every figure, because a two-point gap across 976 flights means less than a ten-point one.

On-time performance by carrier on ATL to PHL
Airline	Flights	On time	Avg delay	Cancelled	Grade
Republic Airwaysthin sample	134	89.0%	94 min	5.22%	A−
PSA Airlines	872	80.9%	96 min	4.47%	B−
Delta Air Lines	3,040	74.3%	53 min	2.47%	C
American Airlines	547	74.2%	124 min	2.01%	C
Frontier Airlines	976	60.4%	85 min	3.48%	D−
Spirit Airlinesthin sample	114	57.1%	78 min	1.75%	D

PSA Airlines cancels 4.5% 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 26 points, against 21 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am794 flights89.1%
8am–11am906 flights80.7%
11am–2pm826 flights81.7%
2pm–5pm1,433 flights65.1%
5pm–8pm724 flights62.7%
8pm–5am1,000 flights64.2%

Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 62.7% on time, against 89.1% 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.

Across the year

When delays peak on this route

This route's year swings by 28 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, June worst

June is the worst month at 56.0% on time, 28 points below September, the best at 84.3%. 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.

Across the week, Wednesday is the strongest day at 78.5% on time and Sunday the weakest at 65.8%. 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 110,000 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.

Late-arriving aircraft
45%
Carrier
34%
National Airspace System
17%
Extreme weather
4%
Security
0%

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 110,000 reported delay minutes here, that single category outweighs weather by 11 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 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 89.1% on time here.

Cancellations run at 2.96%, against 1.80% nationally. That is roughly one flight in 30 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

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.1% of arrivals land a full hour or more behind schedule, against 8.2% 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 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 77.9% on time across 5,685 flights, 5 points above 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 5 points of difference.

The sample behind these figures is 5,683 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 delay figures matter less here than the 2.96% cancellation rate. A late arrival costs you a little over an hour; a cancelled flight costs you the day. Book the 5am–8am departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic.

Common questions

ATL to PHL questions

How often is ATL to PHL delayed?

About one flight in four arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 27.1% of the 5,683 flights in this analysis, against 22.6% nationally. Delayed flights are late by a little over an hour on average.

Which airline is most reliable on ATL to PHL?

PSA Airlines leads at 80.9% on time across 872 flights. Frontier Airlines is at the other end on 60.4%, a gap of 21 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 ATL to PHL?

The 5am–8am departure window is the strongest at 89.1% on time. The 5pm–8pm window is the weakest at 62.7%, 26 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 June delays on ATL to PHL?

June is the weakest month at 56.0% on time, compared with 84.3% in September. Across the year that is 28 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

Direction matters. ATL to PHL and PHL to ATL 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, June 2025 to May 2026. Updated monthly. How this data is collected.

Key figures