Route reliability record

PHL→ATL

Philadelphia to Atlanta

Flights: 5,685
Period: June 2025 to May 2026
Distance: 666 mi
Carriers: 6

This route lands a B, level with the national rate of 77.4%. 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 5,685 flights, of which Delta Air Lines flew 3,043 at 83.5% on time.

Delta Air Lines is the most reliable of the four carriers covered here at 83.5% on time across 3,043 flights.

On time

77.9%

Arrivals under 15 minutes late, of 5,510 completed flights

Avg delay

69 min

Across delayed arrivals only, not all flights

Cancelled

2.76%

National rate is 1.80%

Best carrier

Delta

83.5% on time across 3,043 flights

These figures cover 5,685 flights between June 2025 and May 2026. Beyond the headline rate, 8.0% 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 PHL to ATL

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 83.5% of the time; Frontier Airlines manages 64.4%. Sample sizes sit next to every figure, because a two-point gap across 974 flights means less than a ten-point one.

On-time performance by carrier on PHL to ATL
Airline	Flights	On time	Avg delay	Cancelled	Grade
Republic Airwaysthin sample	134	88.4%	93 min	3.73%	A−
Delta Air Lines	3,043	83.5%	63 min	2.46%	B
PSA Airlines	870	81.8%	70 min	4.02%	B−
American Airlines	551	66.1%	73 min	1.81%	C
Frontier Airlines	974	64.4%	72 min	2.98%	D
Spirit Airlinesthin sample	113	61.8%	75 min	2.65%	D

PSA Airlines cancels 4.0% 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 18 points, against 19 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am1,195 flights83.8%
8am–11am1,115 flights86.4%
11am–2pm891 flights76.0%
2pm–5pm832 flights77.8%
5pm–8pm1,445 flights68.9%
8pm–5am207 flights70.1%

Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.

Book the morning departure. Flights leaving between 8am–11am arrive on time 86.4% of the time, against 68.9% for the evening window. That is 18 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on.

Across the year

When delays peak on this route

This route's year swings by 22 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 66.1% on time, 22 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.

Across the week, Wednesday is the strongest day at 86.4% on time and Sunday the weakest at 71.4%. 15 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 46% of the 83,000 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
46%
Carrier
26%
National Airspace System
24%
Extreme weather
4%
Security
0%

46% 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 83,000 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 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 86.4% on time here.

Cancellations run at 2.76%, against 1.80% 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

8.0% of arrivals land an hour or more late, close to the national 8.2%. 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.

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 72.9% on time across 5,683 flights, 5 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 5 points of difference.

The sample behind these figures is 5,685 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 June 66.1%, a swing of 22 points. If the dates move at all, move them out of June before you think about anything else.

Common questions

PHL to ATL questions

How often is PHL to ATL 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 22.1% of the 5,685 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 PHL to ATL?

Delta Air Lines leads at 83.5% on time across 3,043 flights. Frontier Airlines is at the other end on 64.4%, 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 86.4% on time. The 5pm–8pm window is the weakest at 68.9%, 18 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 PHL to ATL?

June is the weakest month at 66.1% on time, compared with 88.0% in September. Across the year that is 22 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. 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, June 2025 to May 2026. Updated monthly. How this data is collected.

Key figures