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DelayAtlas

Carrier route record

UAPITORD

United Airlines · Pittsburgh to Chicago

Flights
1,290
Period
July 2025 to June 2026
Share of route
33%
Carriers
5
BGRADE

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

United on PIT to ORD lands a B, level with the national rate of 77.6%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by an hour and a half on average. That is a workable record, not a spotless one. That rests on 1,290 flights. The strongest carrier on the route with a full sample, Republic Airways, flew 1,629 at 84.2% on time.

The US average over the same twelve months is 77.6%, so there is little to separate United on PIT to ORD from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

Key figures

On time

77.9%

Arrivals under 15 minutes late, of 1,265 completed flights

Avg delay

95 min

Across delayed arrivals only, not all flights

Cancelled

1.86%

National rate is 1.81%

Whole route

78.6%

Every carrier on PIT to ORD, 3,950 flights

These figures cover 1,290 flights between July 2025 and June 2026. Beyond the headline rate, 9.0% 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

United against every carrier on PIT to ORD

United flew 1,290 of the 3,950 flights on PIT to ORD, about 33% of it. Its 77.9% on time is about level with the route as a whole at 78.6%. Ranked by on-time rate it is number three of five carriers on the route, where the range runs from Republic at 84.2% to SkyWest at 65.1%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The choice of carrier is not cosmetic here. Republic Airways arrives on time 84.2% of the time; American Airlines manages 69.9%. Sample sizes sit next to every figure, because a two-point gap across 604 flights means less than a ten-point one.

On-time performance by carrier on PIT to ORD
AirlineFlightsOn timeAvg delayCancelledGrade
Republic Airways1,62984.2%74 min1.66%B
Envoy Airthin sample19078.3%105 min2.63%B
United Airlines (this page)1,29077.9%95 min1.86%B
American Airlines60469.9%113 min2.98%C
SkyWest Airlinesthin sample23765.1%105 min2.11%C

The spread between Republic and American is 14 points, wide enough that it should decide the booking. On a hundred trips that is 14 more arrivals inside the on-time window.

Departure window

When United runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 39 points, against 14 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

  • 5am–8am366 flights88.9%
  • 8am–11am90 flights84.1%
  • 11am–2pm198 flights92.8%
  • 2pm–5pm326 flights77.7%
  • 5pm–8pm308 flights53.5%
  • 8pm–5am2 flights

Scale runs 45% to 100%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 53.5% on time, against 92.8% for the 11am–2pm 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 5am–8am window is the busiest, with 366 flights scheduled in it.

Across the year

United on PIT to ORD through the year

On-time rate by calendar month70J85F72M78A86M76J74J83A85S83O74N65D
Darker means more delays. Figures are on-time percentages.May best, December worst

December is the weak month at 64.9% on time, against 85.8% in May. 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. May was the busiest month here, with 121 flights.

Across the week, Friday is the strongest day at 82.5% on time and Monday the weakest at 71.1%. 11 points is a smaller lever than departure hour, but it is free.

On-time rate by day of the week71.1Mon81.6Tue77.3Wed78.1Thu82.5Fri80.9Sat74.3Sun
Monday: 71.1 percent on time. Tuesday: 81.6 percent on time. Wednesday: 77.3 percent on time. Thursday: 78.1 percent on time. Friday: 82.5 percent on time. Saturday: 80.9 percent on time. Sunday: 74.3 percent on time

Delay causes

Why United runs late on this route

One category carries most of the weight here. National Airspace System accounts for 52% of the 27,000 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.

  • National Airspace System
    52%
  • Late-arriving aircraft
    27%
  • Carrier
    16%
  • Extreme weather
    4%

52% 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 14,000 minutes out of 27,000, against a national NAS share of 21%. The split is drawn from 26,566 reported delay minutes.

Cancellations sit at 1.86% against a national 1.81%, which is ordinary. Diversions add another 0.08%.

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. 9.0% 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 413 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 11am–2pm window matters as much as it does.

The return leg runs 75.8% on time across 1,291 flights, within 2 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

The sample behind these figures is 1,290 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 United on PIT to ORD

Put together: the calendar is the biggest lever here, not the carrier or the hour. May runs 85.8% on time and December 64.9%, a swing of 21 points. If the dates move at all, move them out of December before you think about anything else. 1,265 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.