BTS DATA COMPLETE THROUGH JUNE 2026HISTORICAL ODDS · NOT LIVE FLIGHT STATUS
DelayOddsKnow the route before you book
ORD→ONT

Chicago, IL (ORD) to Ontario, CA (ONT) flight delay odds

58.3% of 290 official scheduled ORD-to-ONT flights arrived on time; 30.7% arrived at least 30 minutes late and 1.0% were cancelled during July 2025–June 2026.

Source: U.S. Bureau of Transportation Statistics · Reporting window: July 2025–June 2026 · Updated September 16, 2026

HISTORICAL ROUTE SIGNALVariable
58.3%arrived on time
30.7%30+ min late
1.0%cancelled
290scheduled flights
Based on July 2025–June 2026; on time means arrival less than 15 minutes late.
60+ minutes late17.9%all scheduled flights
120+ minutes late7.6%all scheduled flights
Diverted0.0%did not reach as scheduled
Average arrival+27.7 mincompleted flights

Which departure time was most reliable for ORD to ONT?

Only Evening met the ORD-to-ONT departure window threshold: 57.0% of 272 scheduled flights arrived on time during July 2025–June 2026.

Departure windowFlightsOn time30+ minCancelled
Evening27257.0%32.4%1.1%

Which weekday was most reliable for ORD to ONT?

Among qualifying ORD-to-ONT weekday results, Saturday had the highest on-time rate: 69.0% of 42 flights. Friday was lowest at 50.0% across 42 flights.

DayFlightsOn time30+ minCancelled
Monday4151.2%24.4%2.4%
Tuesday4156.1%36.6%0.0%
Wednesday4067.5%27.5%0.0%
Thursday4257.1%33.3%2.4%
Friday4250.0%38.1%2.4%
Saturday4269.0%19.0%0.0%
Sunday4257.1%35.7%0.0%

Which airline was most reliable for ORD to ONT?

Only United Airlines met the ORD-to-ONT airline threshold: 58.3% of 290 scheduled flights arrived on time during July 2025–June 2026.

AirlineFlightsOn time30+ minCancelled
United Airlines29058.3%30.7%1.0%

Which month was most reliable for ORD to ONT?

Among qualifying ORD-to-ONT month results, October 2025 had the highest on-time rate: 80.6% of 31 flights. April 2026 was lowest at 43.3% across 30 flights.

MonthFlightsOn time30+ minCancelled
July 20253145.2%45.2%3.2%
August 20253158.1%25.8%0.0%
September 20253060.0%26.7%0.0%
October 20253180.6%9.7%0.0%
November 20253063.3%26.7%0.0%
March 20262751.9%37.0%3.7%
April 20263043.3%40.0%3.3%
May 20263154.8%32.3%0.0%
June 20263066.7%33.3%0.0%

What drove ORD to ONT delay minutes?

Late aircraft was the largest recorded ORD-to-ONT delay category, accounting for 58.5% of 9,065 BTS-attributed delay minutes during July 2025–June 2026.

Airline22.3%
Late aircraft58.5%
National airspace14.1%
Weather5.1%
Security0.0%
This is historical evidence, not a forecast.

Weather, schedules and operations change. For a trip you have already booked, use the airline or airport for live status.