Ontario International in December 2023

87.3%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 December 2023, reporting carriers scheduled 2,084 domestic departures from Ontario International (ONT). 87.3% left less than 15 minutes late and 88.3% reached their destination on time; 0.1% were cancelled.

Nationally that month, 83.1% of flights departed on time and 83.8% arrived on time, so ONT departures were 4.2 points above the national departure figure.

Flights arriving at ONT that month were on time 87.0% of the time (2,083 scheduled arrivals).

Of the delay minutes that carriers assigned to a BTS cause category that month, late-arriving aircraft 46%, air carrier 32% and national aviation system 21%.

On time 88.3%
Arrived 15+ minutes late 11.5%
Cancelled 0.1%
Diverted 0.1%

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

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

Measure	Dec 2023	Year earlier	ONT, 12 months to Jul 2026	All reported flights, Dec 2023
Departed on time	87.3%	—	80.3%	83.1%
Arrived on time	88.3%	—	81.2%	83.8%
Cancelled	0.1%	—	0.9%	0.4%
Average departure delay (late minutes only)	8.3 min	—	13.7 min	11.6 min
Scheduled departures a day	70	—	71	19,013
Scheduled departures	2,084	—	25,854	570,394

Airlines that month

Reporting carrier	Flights	Share	On time	Avg arrival delay	Cancelled
WN Southwest Airlines	985	47%	90.9%	-4.4 min	0.1%
AA American Airlines	230	11%	86.5%	-1.8 min	0.0%
F9 Frontier Airlines	220	11%	85.0%	2.4 min	0.5%
OO SkyWest Airlines	216	10%	81.5%	1.9 min	0.0%
DL Delta Air Lines	158	8%	95.6%	-11.2 min	0.0%
AS Alaska Airlines	108	5%	88.9%	-3.3 min	0.0%
UA United Airlines	82	4%	90.2%	-5.4 min	0.0%
B6 JetBlue Airways	31	1%	61.3%	31.6 min	0.0%
HA Hawaiian Airlines	31	1%	71.0%	4.5 min	0.0%
MQ Envoy Air	23	1%	95.7%	-5.7 min	0.0%

Busiest routes that month

Route	Cities	Flights	On time	Avg arrival delay	Cancelled
ONT–PHX	Ontario to Phoenix	271	89.3%	-3.1 min	0.0%
ONT–DEN	Ontario to Denver	245	92.7%	-5.2 min	0.0%
ONT–LAS	Ontario to Las Vegas	217	87.6%	-4.3 min	0.0%
ONT–DFW	Ontario to Dallas/Fort Worth	175	82.3%	2.7 min	0.0%
ONT–SEA	Ontario to Seattle	169	85.8%	-4.3 min	0.0%
ONT–OAK	Ontario to Oakland	152	91.4%	-3.9 min	0.0%
ONT–SMF	Ontario to Sacramento	149	91.9%	-9.2 min	0.7%
ONT–SJC	Ontario to San Jose	123	95.9%	-7.1 min	0.0%
ONT–SFO	Ontario to San Francisco	118	73.7%	11.2 min	0.8%
ONT–SLC	Ontario to Salt Lake City	107	97.2%	-11.5 min	0.0%
ONT–ATL	Ontario to Atlanta	80	97.5%	-9.8 min	0.0%
ONT–PDX	Ontario to Portland	33	84.8%	-3.4 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), December 2023.

Delay causes

BTS cause category	Share of delay minutes	National, Dec 2023	Minutes
Air carrier	31.8%	37.1%	4,564
Late-arriving aircraft	45.9%	38.8%	6,600
National Aviation System	20.6%	17.6%	2,957
Extreme weather	1.7%	6.2%	246
Security	0.0%	0.3%	0

14,367 delay minutes on 239 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 December 2023?

87.3% of 2,084 scheduled domestic departures left less than 15 minutes late, and 88.3% reached their destination on time. The national figures that month were 83.1% and 83.8%.

How does that compare with a year earlier?

December 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 December 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.