Carrier route record

F9LAX→ORD

Frontier Airlines · Los Angeles to Chicago

Flights: 227
Period: July 2025 to June 2026
Share of route: 3%
Carriers: 5

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

Frontier on LAX to ORD draws a D−. Roughly one flight in three arrives at least 15 minutes late, and the typical late arrival is about 2.5 hours behind schedule. Build slack into anything you connect to. That rests on 227 flights. The strongest carrier on the route with a full sample, United Airlines, flew 3,380 at 80.5% on time.

The national on-time rate over the same period is 77.6%, so Frontier on LAX to ORD runs 16 points behind the country as a whole. Across a thousand flights that is about 162 extra late arrivals.

On time

61.4%

Arrivals under 15 minutes late, of 215 completed flights

Avg delay

149 min

Across delayed arrivals only, not all flights

Cancelled

4.85%

National rate is 1.81%

Whole route

76.4%

Every carrier on LAX to ORD, 6,964 flights

These figures cover 227 flights between July 2025 and June 2026. Beyond the headline rate, 20.0% 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

Frontier against every carrier on LAX to ORD

Frontier flew 227 of the 6,964 flights on LAX to ORD, about 3% of it. Its 61.4% on time is 15 points worse than the route as a whole, which runs 76.4%. Ranked by on-time rate it is last of five carriers on the route, where the range runs from United at 80.5% to Frontier at 61.4%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The choice of carrier is not cosmetic here. United Airlines arrives on time 80.5% of the time; American Airlines manages 72.9%. Sample sizes sit next to every figure, because a two-point gap across 3,051 flights means less than a ten-point one.

On-time performance by carrier on LAX to ORD
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	3,380	80.5%	67 min	0.74%	B+
Spirit Airlinesthin sample	240	77.7%	75 min	4.17%	B−
American Airlines	3,051	72.9%	96 min	2.33%	C
Delta Air Linesthin sample	66	68.3%	86 min	0.00%	C+
Frontier Airlines (this page)thin sample	227	61.4%	149 min	4.85%	D−

United leads American by 8 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Departure window

When Frontier runs best on this route

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–8am—
8am–11am19 flights—
11am–2pm—
2pm–5pm80 flights77.3%
5pm–8pm42 flights65.0%
8pm–5am86 flights43.2%

Scale runs 35% to 85%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 43.2% on time, against 77.3% 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 8pm–5am window is the busiest, with 86 flights scheduled in it.

Across the year

Frontier on LAX to ORD through the year

Jul–Sep 202565 flights70.5%
Oct–Dec 202571 flights75.0%
Jan–Mar 202631 flights—
Apr–Jun 202660 flights61.4%

Scale runs 55% to 80%. 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 61.4% on time across 227 flights.

Frontier on LAX to ORD did not run the same all year. Its best quarter was Oct–Dec 2025 at 75.0% on time and its weakest Apr–Jun 2026 at 61.4%, a swing of 14 points on roughly 76 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Across the week, Thursday is the strongest day at 66.7% on time and Monday the weakest at 52.6%. 14 points is a smaller lever than departure hour, but it is free.

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 12,000 reported delay minutes.

Late-arriving aircraft
38%
Carrier
36%
Extreme weather
14%
National Airspace System
11%

Extreme weather accounts for 14% 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 2.3 times the usual weather exposure. The split is drawn from 12,325 reported delay minutes.

38% 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 12,000 reported delay minutes here, that single category outweighs weather by 3 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.

Cancellations run at 4.85%, against 1.81% nationally. That is about one flight in twenty 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 costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 20.0% 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.

At 1,744 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.

The return leg is a different operation and performs like one: it runs 66.4% on time across 228 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.

One caution: this is a thin sample. 227 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 LAX to ORD

Put together: the delay figures matter less here than the 4.85% cancellation rate. A late arrival costs you about 2.5 hours; a cancelled flight costs you the day. Book the 2pm–5pm departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 215 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