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DelayAtlas

Carrier route record

UAORDROC

United Airlines · Chicago to Rochester

Flights
587
Period
July 2025 to June 2026
Share of route
25%
Carriers
4
DGRADE

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

United on ORD to ROC draws a D. Roughly one flight in three arrives at least 15 minutes late, and the typical late arrival is about an hour behind schedule. Build slack into anything you connect to. That rests on 587 flights. The strongest carrier on the route with a full sample, Republic Airways, flew 695 at 80.2% on time.

The national on-time rate over the same period is 77.6%, so United on ORD to ROC runs 14 points behind the country as a whole. Across a thousand flights that is about 144 extra late arrivals.

Key figures

On time

63.2%

Arrivals under 15 minutes late, of 579 completed flights

Avg delay

66 min

Across delayed arrivals only, not all flights

Cancelled

1.36%

National rate is 1.81%

Whole route

74.2%

Every carrier on ORD to ROC, 2,320 flights

These figures cover 587 flights between July 2025 and June 2026. Beyond the headline rate, 11.2% 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

United against every carrier on ORD to ROC

United flew 587 of the 2,320 flights on ORD to ROC, about 25% of it. Its 63.2% on time is 11 points worse than the route as a whole, which runs 74.2%. Ranked by on-time rate it is last of four carriers on the route, where the range runs from Republic at 80.2% to United at 63.2%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The two carriers here are closely matched: half a point 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.

On-time performance by carrier on ORD to ROC
AirlineFlightsOn timeAvg delayCancelledGrade
Republic Airways69580.2%67 min2.16%B
Envoy Air81380.1%62 min2.34%B
SkyWest Airlinesthin sample22563.6%68 min4.44%D−
United Airlines (this page)58763.2%66 min1.36%D

No carrier stands out. Republic tops the table at 80.2%, half a point clear of the bottom, which is inside the range this kind of sample moves year to year.

Flight by flight

United flight numbers on ORD to ROC

Departure window

When United 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 587 flights.

  • 5am–8am2 flights
  • 8am–11am
  • 11am–2pm19 flights
  • 2pm–5pm209 flights67.6%
  • 5pm–8pm355 flights60.0%
  • 8pm–5am2 flights

Scale runs 50% to 75%. Rows with fewer than 30 flights show a dash.

The best window here is not the first bank but the 2pm–5pm slot at 67.6% on time, ahead of 5pm–8pm at 60.0%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 5pm–8pm window is the busiest, with 355 flights scheduled in it.

Across the year

United on ORD to ROC through the year

On-time rate by calendar month66JF61M47A66M62J50J70A68S74O66N65D
Darker means more delays. Figures are on-time percentages.October best, April worst

October is the best month on the calendar at 74.1% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. May was the busiest month here, with 62 flights.

Across the week, Thursday is the strongest day at 68.3% on time and Wednesday the weakest at 57.3%. 11 points is a smaller lever than departure hour, but it is free.

On-time rate by day of the week65.5Mon65.9Tue57.3Wed68.3Thu65.9Fri61.8Sat57.6Sun
Monday: 65.5 percent on time. Tuesday: 65.9 percent on time. Wednesday: 57.3 percent on time. Thursday: 68.3 percent on time. Friday: 65.9 percent on time. Saturday: 61.8 percent on time. Sunday: 57.6 percent on time

Delay causes

Why United runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 47% of the 14,000 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.

  • Late-arriving aircraft
    47%
  • Carrier
    31%
  • National Airspace System
    17%
  • Extreme weather
    5%

47% 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 14,000 reported delay minutes here, that single category outweighs weather by 9 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 14,014 reported delay minutes.

Cancellations sit at 1.36% 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. 11.2% 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 528 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 67.6% on time across 591 flights, 4 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 4 points of difference.

One caution: this is a thin sample. 587 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 United on ORD to ROC

Put together: treat all of this as provisional. 587 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 63.2% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 579 completed flights over 12 months sit behind that.

Related

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.