Ontario International in September 2023

84.5%departed on time

BTS: A flight is counted as on time if it arrived less than 15 minutes after its scheduled time. Only carriers with at least 0.5 percent of domestic scheduled passenger revenue report.

In September 2023, reporting carriers scheduled 2,078 domestic departures from Ontario International (ONT). 84.5% left less than 15 minutes late and 85.3% reached their destination on time; 0.6% were cancelled.

Nationally that month, 80.5% of flights departed on time and 80.1% arrived on time, so ONT departures were 4.0 points above the national departure figure.

Flights arriving at ONT that month were on time 77.7% of the time (2,080 scheduled arrivals).

Of the delay minutes that carriers assigned to a BTS cause category that month, late-arriving aircraft 50%, air carrier 31% and national aviation system 20%.

On time 85.3%
Arrived 15+ minutes late 13.9%
Cancelled 0.6%
Diverted 0.2%

Every scheduled departure from ONT in September 2023, judged by arrival at the destination.

September 2023 against a year earlier, the airport's year and the nation

Measure	Sep 2023	Year earlier	ONT, 12 months to Jul 2026	All reported flights, Sep 2023
Departed on time	84.5%	—	80.3%	80.5%
Arrived on time	85.3%	—	81.2%	80.1%
Cancelled	0.6%	—	0.9%	1.2%
Average departure delay (late minutes only)	11.2 min	—	13.7 min	14.1 min
Scheduled departures a day	69	—	71	18,978
Scheduled departures	2,078	—	25,854	569,338

Airlines that month

Reporting carrier	Flights	Share	On time	Avg arrival delay	Cancelled
WN Southwest Airlines	918	44%	84.2%	0.2 min	0.4%
AA American Airlines	280	13%	91.4%	-0.3 min	0.7%
F9 Frontier Airlines	240	12%	84.6%	2.1 min	0.4%
DL Delta Air Lines	177	9%	93.8%	-11.8 min	0.6%
OO SkyWest Airlines	169	8%	84.6%	0.2 min	0.0%
AS Alaska Airlines	148	7%	85.8%	-0.4 min	0.7%
UA United Airlines	86	4%	75.6%	-3.5 min	1.2%
B6 JetBlue Airways	30	1%	43.3%	78.2 min	6.7%
HA Hawaiian Airlines	30	1%	90.0%	-6.1 min	0.0%

Busiest routes that month

Route	Cities	Flights	On time	Avg arrival delay	Cancelled
ONT–LAS	Ontario to Las Vegas	247	78.5%	4.3 min	1.6%
ONT–DEN	Ontario to Denver	237	86.9%	-5.1 min	0.8%
ONT–DFW	Ontario to Dallas/Fort Worth	226	86.3%	-2.4 min	0.4%
ONT–PHX	Ontario to Phoenix	217	87.6%	3.3 min	0.0%
ONT–SEA	Ontario to Seattle	210	89.0%	-4.0 min	0.0%
ONT–SMF	Ontario to Sacramento	151	88.7%	-2.1 min	0.0%
ONT–OAK	Ontario to Oakland	142	83.1%	4.1 min	0.0%
ONT–SFO	Ontario to San Francisco	134	69.4%	8.7 min	0.0%
ONT–SJC	Ontario to San Jose	131	87.0%	0.9 min	0.0%
ONT–SLC	Ontario to Salt Lake City	90	97.8%	-10.3 min	1.1%
ONT–ATL	Ontario to Atlanta	82	96.3%	-14.8 min	0.0%
ONT–AUS	Ontario to Austin	30	80.0%	2.7 min	0.0%

By scheduled departure hour

On-time share:under 62%6270768288% and over

Share of departures that left less than 15 minutes late, by scheduled hour (local time), September 2023.

Delay causes

BTS cause category	Share of delay minutes	National, Sep 2023	Minutes
Air carrier	30.5%	36.4%	6,128
Late-arriving aircraft	49.9%	38.3%	10,010
National Aviation System	19.5%	19.9%	3,923
Extreme weather	0.1%	5.1%	15
Security	0.0%	0.2%	0

20,076 delay minutes on 289 flights that arrived 15 or more minutes late and carried a cause report. Carriers assign the categories; see what each category means.

Questions and answers

How many flights left ONT on time in September 2023?

84.5% of 2,078 scheduled domestic departures left less than 15 minutes late, and 85.3% reached their destination on time. The national figures that month were 80.5% and 80.1%.

How does that compare with a year earlier?

September 2022 is outside the 36 months on file, or the airport had too few reported flights that month.

Provenance

Source: Bureau of Transportation Statistics, Reporting Carrier On-Time Performance, file for September 2023; public domain. Domestic scheduled flights by reporting carriers, totals and averages only. The site's data runs through July 2026. Full record for ONT · methodology · corrections.