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

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

78.0% of 291 official scheduled ONT-to-ORD flights arrived on time; 12.7% arrived at least 30 minutes late and 0.7% 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 SIGNALGenerally reliable
78.0%arrived on time
12.7%30+ min late
0.7%cancelled
291scheduled flights
Based on July 2025–June 2026; on time means arrival less than 15 minutes late.
60+ minutes late5.8%all scheduled flights
120+ minutes late3.8%all scheduled flights
Diverted1.0%did not reach as scheduled
Average arrival+9.9 mincompleted flights

Which departure time was most reliable for ONT to ORD?

Among qualifying ONT-to-ORD departure window results, Early morning had the highest on-time rate: 78.2% of 248 flights. Night was lowest at 76.7% across 43 flights.

Departure windowFlightsOn time30+ minCancelled
Early morning24878.2%12.1%0.4%
Night4376.7%16.3%2.3%

Which weekday was most reliable for ONT to ORD?

Among qualifying ONT-to-ORD weekday results, Monday had the highest on-time rate: 85.7% of 42 flights. Sunday was lowest at 61.9% across 42 flights.

DayFlightsOn time30+ minCancelled
Monday4285.7%14.3%0.0%
Tuesday4175.6%14.6%0.0%
Wednesday4085.0%7.5%0.0%
Thursday4278.6%9.5%0.0%
Friday4273.8%9.5%4.8%
Saturday4285.7%9.5%0.0%
Sunday4261.9%23.8%0.0%

Which airline was most reliable for ONT to ORD?

Only United Airlines met the ONT-to-ORD airline threshold: 78.0% of 291 scheduled flights arrived on time during July 2025–June 2026.

AirlineFlightsOn time30+ minCancelled
United Airlines29178.0%12.7%0.7%

Which month was most reliable for ONT to ORD?

Among qualifying ONT-to-ORD month results, September 2025 had the highest on-time rate: 83.3% of 30 flights. March 2026 was lowest at 70.4% across 27 flights.

MonthFlightsOn time30+ minCancelled
July 20253177.4%12.9%0.0%
August 20253180.6%9.7%0.0%
September 20253083.3%10.0%0.0%
October 20253171.0%3.2%0.0%
November 20253076.7%23.3%0.0%
December 20251580.0%13.3%0.0%
March 20262770.4%22.2%3.7%
April 20263080.0%6.7%3.3%
May 20263174.2%19.4%0.0%
June 20263083.3%10.0%0.0%

What drove ONT to ORD delay minutes?

Airline was the largest recorded ONT-to-ORD delay category, accounting for 43.4% of 4,330 BTS-attributed delay minutes during July 2025–June 2026.

Airline43.4%
Late aircraft17.9%
National airspace38.7%
Weather0.0%
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.