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Route · ONT → DEN · 2020–2025 BTS data

Ontario to Denver

According to PlainFlights' route traffic ranking (BTS On-Time Performance total flights), ONT to DEN (Ontario to Denver) ranks #680 of 4927 tracked domestic routes by total flights (most flights = #1).

Data updated 2026-06-13

84%
On-time
+5 pts
vs US avg
72 min
Delay when late
14,321
Flights
#680 of 4927
Corpus placement

Cancelled

0.7%

Best Month

Sep 2024 90%

Worst Month

Jul 2025 66%

Distance

819 mi

Carriers

12

Monthly Performance

Recent 24 months of route data.

Period Flights Delayed Cancelled Diverted Carriers
Dec 2025 195 44 0 1 WN,F9,UA
Nov 2025 220 36 0 0 UA,F9,WN
Oct 2025 241 33 2 0 UA,WN,F9
Sep 2025 237 45 0 0 UA,WN,F9
Aug 2025 254 66 1 2 WN,F9,UA
Jul 2025 272 93 3 2 UA,WN,F9
Jun 2025 260 86 3 3 UA,WN,F9
May 2025 261 80 4 3 OO,UA,WN,F9
Apr 2025 252 57 1 1 F9,OO,UA,WN
Mar 2025 213 30 0 1 UA,WN,F9
Feb 2025 187 22 0 0 UA,WN,F9
Jan 2025 208 41 2 0 UA,WN,F9
Dec 2024 223 24 0 0 F9,UA,WN
Nov 2024 224 28 2 0 UA,WN,F9
Oct 2024 259 25 0 0 UA,WN,F9
Sep 2024 249 24 0 0 WN,UA,F9
Aug 2024 263 44 3 2 F9,WN,UA
Jul 2024 273 46 6 1 F9,UA,WN
Jun 2024 262 49 1 1 F9,UA,WN
May 2024 247 39 1 0 F9,OO,UA,WN
Apr 2024 228 29 1 0 F9,UA,WN
Mar 2024 226 31 3 0 F9,UA,WN
Feb 2024 219 40 2 0 F9,UA,WN
Jan 2024 229 26 4 0 F9,WN,UA

ONT–DEN seasonal on-time pattern

Best: March (87.6%) · weakest: July (78.7%)

78%80%82%84%86%88%90% JanFebMarAprMayJunJulAugSepOctNovDec 85.5%

Strongest calendar month

March

87.6% on-time · ~183 flights/mo

Busiest calendar month

August

~233 flights/mo avg

Weakest calendar month

July

78.7% on-time · ~228 flights/mo

Cancellation Rate

0.7%

39 of 5,702 flights

Diversion Rate

0.3%

17 of 5,702 flights

Explore origin & destination

On-time and delay data for the airports this route connects.

ONT - Ontario

Full on-time, delay-cause, and seasonal performance for Ontario, CA.

ONT on-time profile

DEN - Denver

Full on-time, delay-cause, and seasonal performance for Denver, CO.

DEN on-time profile

Compare the two airports

See ONT and DEN side by side on delays, cancellations, and reliability.

Compare ONT vs DEN

Origin-hub reliability standing

Mid-pack among ONT departures

From ONT, this corridor sits with 9 other 75–85% on-time routes out of 21 tracked departures, not the hub's reliability leaders (10 at ≥85%) and not the softest ( 2 below 75%). Destination: Denver · fleet on-time rank #1582 of 4927.

What the Data Says About ONT to DEN

Bureau of Transportation Statistics records show Ontario to Denver (ONT to DEN) running a 84% on-time rate over 14,321 tracked flights, on the stronger end of a typical domestic pairing. When flights do run late, the average delay is 72.2 minutes. The 819-mile corridor is served by 12 carriers, and over the last 24 months 0.7% of 5,702 flights were cancelled, 0.3% diverted.

The monthly split is wide on this route: Sep 2024 posted the strongest performance at 90% on-time, while Jul 2025 came in at just 66% - a 25-point swing worth factoring into travel timing.

On the multi-year calendar, ONT–DEN peaks in March at 87.6% on-time while August carries the heaviest traffic (~233 flights per month) ; the softest month is July at 78.7%, a 8.9-point swing that repeats because the corridor's weather and holiday mix stays stable year to year.

Frequently Asked Questions

Where does ONT to DEN rank among US routes by traffic? ▼
According to PlainFlights' route traffic ranking, ONT to DEN ranks #680 of 4927 tracked domestic routes by total flights (most flights = #1). That ordinal matches our busiest-routes listing (total_flights DESC). See /methodology#corpus-placement for the exact sort basis.
How often are flights delayed from ONT to DEN? ▼
Flights from Ontario to Denver have a 84% on-time rate based on 14,321 flights. The average delay is 72.2 minutes. The best recent month was Sep 2024 with 90% on-time.
What is the cancellation rate for ONT to DEN? ▼
Over the last 24 months, 0.7% of flights on this route were cancelled (39 of 5,702 flights) and 0.3% were diverted.
How far is the flight from ONT to DEN? ▼
The flight distance from Ontario (ONT) to Denver (DEN) is approximately 819 miles. This route is served by 12 carriers.
When is the best time to fly from ONT to DEN? ▼
The best recent month for on-time performance was Sep 2024 (90% on-time). The worst was Jul 2025 (66% on-time). Consider booking during months with historically better performance.

Airports on this route

ONT Airport

Ontario
DEN Airport

Denver
Data source

Data Source: Bureau of Transportation Statistics (BTS), On-Time Performance Data. Statistics reflect cumulative performance across all available reporting periods.

Read our methodology - how this data is sourced, computed, and verified.

Using ONT–DEN data

ONT–DEN runs 5 pts above the national 79% average; the remaining risk is month-to-month swing and carrier mix, not a weak headline rate.

  • Compare ONT and DEN airport profiles: delay causes and top routes differ even on the same corridor. ONT airport
  • If your dates flex, March (87.6% on-time) beats July (78.7%) on this corridor. Seasonal chart
  • 4 other routes post a similar 84% on-time rate; compare before you commit to this pairing. Similar routes

On-time rate reflects the BTS historical average across all reporting carriers on this origin–destination pair, not any single flight or booking recommendation.

Data sourced from U.S. Department of Transportation Bureau of Transportation Statistics (BTS) On-Time Performance data. See our methodology for details. Retrieved and formatted by PlainFlights

Every figure on PlainFlights is rendered directly from BTS On-Time Performance data, no number is typed in by an editor. This page aggregates this specific route's on-time performance and monthly trend, live from the dataset. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.