Route reliability record
PHL→BOS
Philadelphia to Boston
- Flights
- 4,909
- Period
- June 2025 to May 2026
- Distance
- 280 mi
- Carriers
- 4
This route sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 3 points worse than the national rate of 77.4%. The late ones land a little over an hour behind schedule. That rests on 4,909 flights, of which Republic Airways flew 1,745 at 79.8% on time.
Republic Airways is the most reliable of the three carriers covered here at 79.8% on time across 1,745 flights.
Key figures
On time
74.7%
Arrivals under 15 minutes late, of 4,763 completed flights
Avg delay
79 min
Across delayed arrivals only, not all flights
Cancelled
2.97%
National rate is 1.80%
Best carrier
Republic
79.8% on time across 1,745 flights
These figures cover 4,909 flights between June 2025 and May 2026. Beyond the headline rate, 12.0% 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 BOS
The choice of carrier is not cosmetic here. Republic Airways arrives on time 79.8% of the time; American Airlines manages 71.5%. Sample sizes sit next to every figure, because a two-point gap across 2,205 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Frontier Airlinesthin sample | 65 | 85.9% | 53 min | 1.54% | A |
| Republic Airways | 1,745 | 79.8% | 77 min | 3.21% | B− |
| JetBlue Airways | 894 | 71.8% | 74 min | 2.35% | C |
| American Airlines | 2,205 | 71.5% | 82 min | 3.08% | C− |
Republic Airways cancels 3.2% 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 34 points, against 8 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am794 flights91.8%
- 8am–11am1,156 flights84.5%
- 11am–2pm774 flights77.4%
- 2pm–5pm745 flights63.8%
- 5pm–8pm1,090 flights57.9%
- 8pm–5am350 flights70.8%
Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 57.9% on time, against 91.8% 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 23 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.
Delays peak in September, when the on-time rate falls to 60.7%. February is the strongest month at 83.4%. Moving a flexible trip across that boundary buys 23 points.
Across the week, Saturday is the strongest day at 82.1% on time and Sunday the weakest at 69.8%. 12 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 95,000 reported delay minutes.
- 41%Late-arriving aircraft
- 31%National Airspace System
- 23%Carrier
- 5%Extreme weather
- 0%Security
41% 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 95,000 reported delay minutes here, that single category outweighs weather by 8 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 91.8% on time here.
Cancellations run at 2.97%, 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. 12.0% 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.
At 280 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 5am–8am window matters as much as it does.
The return leg runs 75.6% on time across 4,913 flights, within about a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 4,909 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 2.97% 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
PHL to BOS questions
How often is PHL to BOS 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 25.3% of the 4,909 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 BOS?
Republic Airways leads at 79.8% on time across 1,745 flights. American Airlines is at the other end on 71.5%, a gap of 8 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 BOS?
The 5am–8am departure window is the strongest at 91.8% on time. The 5pm–8pm window is the weakest at 57.9%, 34 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 September delays on PHL to BOS?
September is the weakest month at 60.7% on time, compared with 83.4% in February. Across the year that is 23 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
- BOS to PHL — the return legseparate record
- Philadelphia International (PHL) delay statistics
- Boston Logan International (BOS) delay statistics
- Frontier Airlines on-time record85.9%
- Republic Airways on-time record79.8%
- JetBlue Airways on-time record71.8%
- Why the first flight of the morning is statistically safest
- What a cancellation rate actually tells you (and what it hides)
Direction matters. PHL to BOS and BOS 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.