Route reliability record
SLC→ORD
Salt Lake City to Chicago
- Flights
- 3,198
- Period
- July 2025 to June 2026
- Distance
- 1,250 mi
- Carriers
- 5
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 an hour and a half behind schedule. That rests on 3,198 flights, of which Delta Air Lines flew 1,010 at 76.8% on time.
Delta Air Lines is the most reliable of the three carriers covered here at 76.8% on time across 1,010 flights.
Key figures
On time
75.3%
Arrivals under 15 minutes late, of 3,137 completed flights
Avg delay
90 min
Across delayed arrivals only, not all flights
Cancelled
1.22%
National rate is 1.81%
Best carrier
Delta
76.8% on time across 1,010 flights
These figures cover 3,198 flights between July 2025 and June 2026. Beyond the headline rate, 9.9% 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 SLC to ORD
The three carriers here are closely matched: 3 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 |
|---|---|---|---|---|---|
| SkyWest Airlinesthin sample | 115 | 77.0% | 122 min | 1.74% | B |
| Delta Air Lines | 1,010 | 76.8% | 70 min | 0.69% | B+ |
| United Airlines | 1,069 | 75.4% | 89 min | 1.12% | B |
| American Airlines | 968 | 74.0% | 106 min | 1.86% | C |
| Envoy Airthin sample | 36 | 61.1% | 80 min | 0.00% | D+ |
No carrier stands out. Delta tops the table at 76.8%, 3 points clear of the bottom, which is inside the range this kind of sample moves year to year.
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 25 points, against 3 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am658 flights88.6%
- 8am–11am516 flights86.2%
- 11am–2pm764 flights72.1%
- 2pm–5pm685 flights63.2%
- 5pm–8pm575 flights68.6%
- 8pm–5am—
Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 88.6% of the time, against 63.2% for the afternoon window. That is 25 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 764 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 18 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 65.7% on time, 18 points below February, the best at 83.4%. 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. March was the busiest month here, with 317 flights.
Across the week, Tuesday is the strongest day at 79.9% on time and Monday the weakest at 72.3%. 8 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 69,000 reported delay minutes.
- 38%National Airspace System
- 31%Carrier
- 26%Late-arriving aircraft
- 5%Extreme weather
38% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 26,000 minutes out of 69,000, against a national NAS share of 21%. The split is drawn from 69,406 reported delay minutes.
Cancellations sit at 1.22% against a national 1.81%, which is ordinary. Diversions add another 0.69%.
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. 9.9% 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 1,250 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 68.8% on time across 3,198 flights, 7 points below 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 7 points of difference.
The sample behind these figures is 3,198 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 calendar is the biggest lever here, not the carrier or the hour. February runs 83.4% on time and July 65.7%, a swing of 18 points. If the dates move at all, move them out of July before you think about anything else. 3,137 completed flights over 12 months sit behind that.
Common questions
SLC to ORD questions
How often is SLC to ORD 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 24.7% of the 3,198 flights in this analysis, against 22.4% nationally. Delayed flights are late by an hour and a half on average.
Which airline is most reliable on SLC to ORD?
Delta Air Lines leads at 76.8% on time across 1,010 flights. American Airlines is at the other end on 74.0%, a gap of 3 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 SLC to ORD?
The 5am–8am departure window is the strongest at 88.6% on time. The 2pm–5pm window is the weakest at 63.2%, 25 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 SLC to ORD?
July is the weakest month at 65.7% on time, compared with 83.4% in February. Across the year that is 18 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
- ORD to SLC — the return legseparate record
- Salt Lake City International (SLC) delay statistics
- Chicago O'Hare International (ORD) delay statistics
- SkyWest Airlines on-time record77.0%
- Delta Air Lines on-time record76.8%
- United Airlines on-time record75.4%
- The best time of day to fly, according to 7.04 million flight records
- Connecting flights: how much buffer the data says you need
Direction matters. SLC to ORD and ORD to SLC 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, July 2025 to June 2026. Updated monthly. How this data is collected.