Carrier route record

F9RDU→DEN

Frontier Airlines · Raleigh to Denver

Flights: 286
Period: July 2025 to June 2026
Share of route: 16%
Carriers: 3

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

Frontier on RDU to DEN lands a B, level with the national rate of 77.6%. Roughly one flight in four arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 286 flights. The strongest carrier on the route with a full sample, United Airlines, flew 776 at 86.3% on time.

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

On time

77.5%

Arrivals under 15 minutes late, of 280 completed flights

Avg delay

71 min

Across delayed arrivals only, not all flights

Cancelled

1.40%

National rate is 1.81%

Whole route

80.0%

Every carrier on RDU to DEN, 1,771 flights

These figures cover 286 flights between July 2025 and June 2026. Beyond the headline rate, 8.6% 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 RDU to DEN

Frontier flew 286 of the 1,771 flights on RDU to DEN, about 16% of it. Its 77.5% on time is 3 points worse than the route as a whole, which runs 80.0%. Ranked by on-time rate it is number two of three carriers on the route, where the range runs from United at 86.3% to Southwest at 74.0%.

The choice of carrier is not cosmetic here. United Airlines arrives on time 86.3% of the time; Southwest Airlines manages 74.0%. Sample sizes sit next to every figure, because a two-point gap across 709 flights means less than a ten-point one.

On-time performance by carrier on RDU to DEN
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	776	86.3%	90 min	0.64%	A+
Frontier Airlines (this page)thin sample	286	77.5%	71 min	1.40%	B
Southwest Airlines	709	74.0%	55 min	0.85%	C+

The spread between United and Southwest is 12 points, wide enough that it should decide the booking. On a hundred trips that is 12 more arrivals inside the on-time window.

Flight by flight

Frontier flight numbers on RDU to DEN

F9 222517:2376.2% · 253 flights

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

5am–8am—
8am–11am1 flights—
11am–2pm57 flights96.4%
2pm–5pm3 flights—
5pm–8pm205 flights71.3%
8pm–5am20 flights—

Scale runs 65% to 100%. Rows with fewer than 30 flights show a dash.

The best window here is not the first bank but the 11am–2pm slot at 96.4% on time, ahead of 5pm–8pm at 71.3%. 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 205 flights scheduled in it.

Across the year

Frontier on RDU to DEN through the year

Jul–Sep 202568 flights53.0%
Oct–Dec 202565 flights73.8%
Jan–Mar 202664 flights88.7%
Apr–Jun 202689 flights90.8%

Scale runs 45% to 95%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 77.5% on time across 286 flights.

Frontier on RDU to DEN did not run the same all year. Its best quarter was Apr–Jun 2026 at 90.8% on time and its weakest Jul–Sep 2025 at 53.0%, a swing of 38 points on roughly 72 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Across the week, Saturday is the strongest day at 83.8% on time and Monday the weakest at 65.4%. 18 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Frontier runs late on this route

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 4,468 reported delay minutes.

Late-arriving aircraft
39%
National Airspace System
31%
Extreme weather
21%
Carrier
9%

Extreme weather accounts for 21% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 3.4 times the usual weather exposure. The split is drawn from 4,468 reported delay minutes.

39% 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 4,468 reported delay minutes here, that single category outweighs weather by 2 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.

Cancellations sit at 1.40% against a national 1.81%, which is ordinary. Diversions add another 0.70%.

Connections and stage length

What a delay here costs

8.6% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last a little over an hour, which a normal layover absorbs.

The 1,436 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 86.1% on time across 285 flights, 9 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 9 points of difference.

One caution: this is a thin sample. 286 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 RDU to DEN

Put together: treat all of this as provisional. 286 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 77.5% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 280 completed flights over 12 months sit behind that.

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.

Key figures