Carrier route record
F9ATL→ORD
Frontier Airlines · Atlanta to Chicago
- Flights
- 711
- Period
- July 2025 to June 2026
- Share of route
- 11%
- Carriers
- 9
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Frontier Airlines.
Frontier on ATL to ORD draws a D. Roughly one flight in three arrives at least 15 minutes late, and the typical late arrival is close to two hours behind schedule. Build slack into anything you connect to. That rests on 711 flights. The strongest carrier on the route with a full sample, United Airlines, flew 1,611 at 74.3% on time.
United Airlines is the most reliable of the three carriers covered here at 74.3% on time across 1,611 flights.
Key figures
On time
62.8%
Arrivals under 15 minutes late, of 691 completed flights
Avg delay
111 min
Across delayed arrivals only, not all flights
Cancelled
2.67%
National rate is 1.81%
Whole route
70.6%
Every carrier on ATL to ORD, 6,406 flights
These figures cover 711 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 ATL to ORD
Frontier flew 711 of the 6,406 flights on ATL to ORD, about 11% of it. Its 62.8% on time is 8 points worse than the route as a whole, which runs 70.6%. Ranked by on-time rate it is last of nine carriers on the route, where the range runs from PSA at 100.0% to Frontier at 62.8%. Five of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The three carriers here are closely matched: 5 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| PSA Airlinesthin sample | 5 | 100.0% | — | 0.00% | A+ |
| SkyWest Airlinesthin sample | 40 | 84.2% | 88 min | 5.00% | B− |
| Spirit Airlinesthin sample | 75 | 83.8% | 38 min | 0.00% | B+ |
| United Airlines | 1,611 | 74.3% | 92 min | 1.55% | C |
| Republic Airwaysthin sample | 287 | 72.4% | 65 min | 5.92% | C− |
| American Airlines | 688 | 72.2% | 98 min | 3.05% | C− |
| Envoy Airthin sample | 364 | 71.3% | 83 min | 2.20% | C |
| Delta Air Lines | 2,625 | 69.1% | 63 min | 2.21% | C |
| Frontier Airlines (this page) | 711 | 62.8% | 111 min | 2.67% | D |
American Airlines cancels 3.0% 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.
Flight by flight
Frontier flight numbers on ATL to ORD
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 32 points, against 5 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am66 flights78.8%
- 8am–11am223 flights71.4%
- 11am–2pm28 flights—
- 2pm–5pm80 flights63.8%
- 5pm–8pm92 flights46.7%
- 8pm–5am222 flights54.3%
Scale runs 40% to 85%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 46.7% on time, against 78.8% 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. The 8am–11am window is the busiest, with 223 flights scheduled in it.
Across the year
Frontier on ATL to ORD through the year
December is the weak month at 43.9% on time, against 88.2% in February. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. October was the busiest month here, with 68 flights.
Across the week, Wednesday is the strongest day at 69.3% on time and Monday the weakest at 57.0%. 12 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Frontier runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 48% of the 28,000 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.
- 48%Late-arriving aircraft
- 26%Carrier
- 25%National Airspace System
- 0%Extreme weather
48% 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 28,000 reported delay minutes here, that single category outweighs weather by 48 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 28,493 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 78.8% on time here.
Cancellations run at 2.67%, against 1.81% nationally. That is about 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 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.
The 606 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 67.8% on time across 713 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. 711 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 ATL to ORD
Put together: treat all of this as provisional. 711 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 62.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 691 completed flights over 12 months sit behind that.
Related
Where to go next
- ATL to ORD, every carrier
- Frontier on ORD to ATL, the return leg
- United Airlines on ATL to ORD74.3%
- Republic Airways on ATL to ORD72.4%
- American Airlines on ATL to ORD72.2%
- Envoy Air on ATL to ORD71.3%
- Delta Air Lines on ATL to ORD69.1%
- Frontier Airlines network-wide record
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Chicago O'Hare International (ORD) delay statistics
- The US routes with the most cancellations
- Why the first flight of the morning is statistically safest
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.