Carrier route record

F9PHX→MDW

Frontier Airlines · Phoenix to Chicago

Flights: 127
Period: July 2025 to June 2026
Share of route: 5%
Carriers: 2

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Frontier Airlines.

Frontier on PHX to MDW draws a C. About one flight in three arrives at least 15 minutes late, and the typical late arrival is a little over an hour behind schedule. Build slack into anything you connect to. That rests on 127 flights, with a median arrival 6 minutes early.

The national on-time rate over the same period is 77.6%, so Frontier on PHX to MDW runs 11 points behind the country as a whole. Across a thousand flights that is about 112 extra late arrivals.

On time

66.4%

Arrivals under 15 minutes late, of 125 completed flights

Avg delay

80 min

Across delayed arrivals only, not all flights

Cancelled

1.57%

National rate is 1.81%

Whole route

73.1%

Every carrier on PHX to MDW, 2,803 flights

These figures cover 127 flights between July 2025 and June 2026. Beyond the headline rate, 12.8% 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

Frontier against every carrier on PHX to MDW

Frontier flew 127 of the 2,803 flights on PHX to MDW, about 5% of it. Its 66.4% on time is 7 points worse than the route as a whole, which runs 73.1%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from Southwest at 73.4% to Frontier at 66.4%.

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.

On-time performance by carrier on PHX to MDW
Airline	Flights	On time	Avg delay	Cancelled	Grade
Southwest Airlines	2,676	73.4%	47 min	1.05%	C
Frontier Airlines (this page)thin sample	127	66.4%	80 min	1.57%	C

Departure window

When Frontier runs best on this route

Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 127 flights.

5am–8am7 flights—
8am–11am26 flights—
11am–2pm16 flights—
2pm–5pm40 flights65.0%
5pm–8pm38 flights56.8%
8pm–5am—

Scale runs 50% to 70%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 56.8% on time, against 65.0% for the 2pm–5pm 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 2pm–5pm window is the busiest, with 40 flights scheduled in it.

Across the year

Frontier on PHX to MDW through the year

Jul–Sep 202526 flights—
Oct–Dec 202538 flights78.4%
Jan–Mar 202651 flights62.0%
Apr–Jun 202612 flights—

Scale runs 55% to 85%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 66.4% on time across 127 flights.

Split by quarter, Frontier on PHX to MDW logged 26 flights in Jul–Sep 2025, 38 flights in Oct–Dec 2025, 51 flights in Jan–Mar 2026 and 12 flights in Apr–Jun 2026. Fewer than three of those quarters carried the 30 completed flights this site needs before printing a rate, so the 66.4% annual figure is the one to use.

Delay causes

Why Frontier runs late on this route

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 3,375 reported delay minutes.

Carrier
37%
Late-arriving aircraft
32%
Extreme weather
22%
National Airspace System
8%

Extreme weather accounts for 22% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 3.5 times the usual weather exposure. The split is drawn from 3,375 reported delay minutes.

The largest share of delay minutes, 37%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 1,264 of the 3,375 delay minutes reported here.

Cancellations sit at 1.57% against a national 1.81%, which is ordinary. Diversions add another 0.00%.

Connections and stage length

What a delay here costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 12.8% of arrivals land a full hour or more behind schedule, against 8.1% 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 1,444 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 75.2% on time across 127 flights, 9 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 9 points of difference.

One caution: this is a thin sample. 127 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.

What to do with this

Booking Frontier on PHX to MDW

Put together: treat all of this as provisional. 127 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 66.4% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 125 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures