Route reliability record

RDU→ORD

Raleigh to Chicago

Flights: 3,589
Period: July 2025 to June 2026
Distance: 646 mi
Carriers: 7

This route sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 3 points worse than the national rate of 77.6%. The late ones land an hour and a half behind schedule. That rests on 3,589 flights, of which American Airlines flew 553 at 82.2% on time.

American Airlines is the most reliable of the four carriers covered here at 82.2% on time across 553 flights.

On time

74.4%

Arrivals under 15 minutes late, of 3,482 completed flights

Avg delay

93 min

Across delayed arrivals only, not all flights

Cancelled

2.42%

National rate is 1.81%

Best carrier

American

82.2% on time across 553 flights

These figures cover 3,589 flights between July 2025 and June 2026. Beyond the headline rate, 10.7% 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 RDU to ORD

The choice of carrier is not cosmetic here. American Airlines arrives on time 82.2% of the time; Republic Airways manages 70.7%. Sample sizes sit next to every figure, because a two-point gap across 1,018 flights means less than a ten-point one.

On-time performance by carrier on RDU to ORD
Airline	Flights	On time	Avg delay	Cancelled	Grade
American Airlines	553	82.2%	145 min	3.44%	B−
SkyWest Airlinesthin sample	67	77.3%	138 min	0.00%	B+
United Airlines	1,295	76.3%	87 min	1.16%	B
Envoy Air	523	72.3%	86 min	1.72%	C
Republic Airways	1,018	70.7%	75 min	3.63%	C−
Frontier Airlinesthin sample	131	57.7%	139 min	5.34%	D−
PSA Airlinesthin sample	2	50.0%	31 min	0.00%	F+

Republic Airways cancels 3.6% 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.

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 45 points, against 12 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am780 flights87.5%
8am–11am708 flights88.8%
11am–2pm691 flights78.4%
2pm–5pm627 flights65.3%
5pm–8pm748 flights51.9%
8pm–5am35 flights43.8%

Scale runs 35% to 95%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 43.8% on time, against 88.8% for the 8am–11am 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 780 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.

Darker means more delays. Figures are on-time percentages.September best, July worst

July is the worst month at 65.2% on time, 18 points below September, the best at 82.7%. 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. May was the busiest month here, with 374 flights.

Across the week, Tuesday is the strongest day at 77.4% on time and Friday the weakest at 71.3%. 6 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 83,000 reported delay minutes.

National Airspace System
35%
Late-arriving aircraft
35%
Carrier
23%
Extreme weather
7%
Security
0%

35% 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 83,000 reported delay minutes here, that single category outweighs weather by 5 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 83,068 reported delay minutes.

35% 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 29,000 minutes out of 83,000, against a national NAS share of 21%.

Cancellations sit at 2.42% against a national 1.81%, which is ordinary. Diversions add another 0.56%.

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. 10.7% 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 646 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 runs 73.3% on time across 3,592 flights, within about a point 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 3,589 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. September runs 82.7% on time and July 65.2%, a swing of 18 points. If the dates move at all, move them out of July before you think about anything else. 3,482 completed flights over 12 months sit behind that.

Common questions

RDU to ORD questions

How often is RDU 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 25.6% of the 3,589 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 RDU to ORD?

American Airlines leads at 82.2% on time across 553 flights. Republic Airways is at the other end on 70.7%, a gap of 12 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 RDU to ORD?

The 8am–11am departure window is the strongest at 88.8% on time. The 8pm–5am window is the weakest at 43.8%, 45 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 RDU to ORD?

July is the weakest month at 65.2% on time, compared with 82.7% in September. 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.

Where to go next

Direction matters. RDU to ORD and ORD to RDU 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.

Key figures