Route reliability record
MDW→PHL
Chicago to Philadelphia
- Flights
- 1,525
- Period
- July 2025 to June 2026
- Distance
- 668 mi
- Carriers
- 2
This route sits in the middle of the pack with a B. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 1,525 MDW to PHL flights, with a median arrival 2 minutes early.
Best time to fly MDW to PHL: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 92.3% of the time and Saturday flights 82.9%, against 75.7% for the route overall.
The US average over the same twelve months is 77.6%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
75.7%
Arrivals under 15 minutes late, of 1,500 completed flights
Avg delay
61 min
Across delayed arrivals only, not all flights
Cancelled
1.44%
National rate is 1.81%
Best carrier
Southwest
75.5% on time across 1,449 flights
These figures cover 1,525 flights between July 2025 and June 2026. The median arrival is 2 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 MDW to PHL
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Frontier Airlinesthin sample | 76 | 79.7% | 135 min | 2.63% | B |
| Southwest Airlines | 1,449 | 75.5% | 58 min | 1.38% | B |
Best ways to make this trip
The most reliable ways to fly Chicago to Philadelphia
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 2 of the top 3 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. MDW → PHLChicago to Philadelphia | Southwest Airlines | 74.5% | 75.5% | 1.38% | 5am–8am, Sat (route) | — |
| 2. ORD → PHLChicago to Philadelphia | United Airlines | 71.3% | 72.2% | 1.30% | 5am–8am, Tue | UA 2418 07:25 |
| 3. ORD → PHLChicago to Philadelphia | American Airlines | 68.4% | 71.1% | 3.76% | 5am–8am, Tue | AA 2840 14:50 |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
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 42 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am195 flights92.3%
- 8am–11am343 flights86.9%
- 11am–2pm273 flights79.0%
- 2pm–5pm332 flights64.0%
- 5pm–8pm301 flights68.5%
- 8pm–5am81 flights50.6%
Scale runs 40% to 100%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 50.6% on time, against 92.3% 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. The 8am–11am window is the busiest, with 343 flights scheduled in it.
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.
July is the worst month at 63.1% on time, 23 points below April, the best at 86.4%. 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. September was the busiest month here, with 159 flights.
Across the week, Saturday is the strongest day at 82.9% on time and Thursday the weakest at 70.5%. 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 22,000 reported delay minutes.
- 37%Late-arriving aircraft
- 28%Carrier
- 25%National Airspace System
- 9%Extreme weather
- 1%Security
37% 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 22,000 reported delay minutes here, that single category outweighs weather by 4 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 22,311 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 92.3% on time here.
Cancellations sit at 1.44% against a national 1.81%, which is ordinary. Diversions add another 0.20%.
Connections and stage length
What a delay here actually costs
6.5% 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 last about an hour, which a normal layover absorbs.
The 668 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 runs 73.2% on time across 1,528 flights, within 3 points 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 1,525 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.
Work out the risk of missing a connection in PHL after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. April runs 86.4% on time and July 63.1%, a swing of 23 points. If the dates move at all, move them out of July before you think about anything else. 1,500 completed flights over 12 months sit behind that.
Common questions
MDW to PHL questions
How often is MDW to PHL delayed?
About one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 24.3% of the 1,525 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
How reliable is MDW to PHL compared with the rest of the country?
75.7% of flights arrive on time here against a national 77.6%, a difference of 2 points against it. That is worth a B on this site's grading scale.
What time of day has the fewest delays on MDW to PHL?
The 5am–8am departure window is the strongest at 92.3% on time. The 8pm–5am window is the weakest at 50.6%, 42 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 MDW to PHL?
July is the weakest month at 63.1% on time, compared with 86.4% in April. 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
- PHL to MDW — the return legseparate record
- Chicago Midway International (MDW) delay statistics
- Philadelphia International (PHL) delay statistics
- MDW to ATL, a related route79.8%
- ATL to PHL, a related route74.9%
- MDW to PHX, a related route75.0%
- Frontier Airlines on-time record79.7%
- Southwest Airlines on-time record75.5%
- 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. MDW to PHL and PHL to MDW are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.