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

Atlanta, GA (ATL) to Ontario, CA (ONT) flight delay odds

75.2% of 937 official scheduled ATL-to-ONT flights arrived on time; 14.1% arrived at least 30 minutes late and 1.7% 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
75.2%arrived on time
14.1%30+ min late
1.7%cancelled
937scheduled flights
Based on July 2025–June 2026; on time means arrival less than 15 minutes late.
60+ minutes late6.9%all scheduled flights
120+ minutes late1.8%all scheduled flights
Diverted0.1%did not reach as scheduled
Average arrival+7.4 mincompleted flights

Which departure time was most reliable for ATL to ONT?

Among qualifying ATL-to-ONT departure window results, Early morning had the highest on-time rate: 84.2% of 57 flights. Night was lowest at 51.3% across 76 flights.

Departure windowFlightsOn time30+ minCancelled
Early morning5784.2%5.3%5.3%
Late morning30883.1%8.4%1.9%
Afternoon7962.0%22.8%0.0%
Evening41775.1%14.4%1.4%
Night7651.3%32.9%1.3%

Which weekday was most reliable for ATL to ONT?

Among qualifying ATL-to-ONT weekday results, Wednesday had the highest on-time rate: 81.2% of 133 flights. Monday was lowest at 72.7% across 139 flights.

DayFlightsOn time30+ minCancelled
Monday13972.7%16.5%0.7%
Tuesday13773.0%16.8%0.7%
Wednesday13381.2%8.3%0.8%
Thursday13676.5%12.5%2.2%
Friday13775.2%16.1%1.5%
Saturday11675.0%12.9%3.4%
Sunday13973.4%15.1%2.9%

Which airline was most reliable for ATL to ONT?

Only Delta Air Lines met the ATL-to-ONT airline threshold: 75.2% of 937 scheduled flights arrived on time during July 2025–June 2026.

AirlineFlightsOn time30+ minCancelled
Delta Air Lines93775.2%14.1%1.7%

Which month was most reliable for ATL to ONT?

Among qualifying ATL-to-ONT month results, March 2026 had the highest on-time rate: 85.5% of 62 flights. January 2026 was lowest at 68.8% across 64 flights.

MonthFlightsOn time30+ minCancelled
July 20258871.6%21.6%1.1%
August 20258275.6%12.2%1.2%
September 20257783.1%5.2%0.0%
October 20258580.0%7.1%0.0%
November 20258482.1%15.5%1.2%
December 20258869.3%13.6%4.5%
January 20266468.8%18.8%6.2%
February 20265673.2%14.3%0.0%
March 20266285.5%6.5%3.2%
April 20267875.6%9.0%0.0%
May 20269369.9%17.2%1.1%
June 20268070.0%26.2%2.5%

What drove ATL to ONT delay minutes?

Airline was the largest recorded ATL-to-ONT delay category, accounting for 50.5% of 11,821 BTS-attributed delay minutes during July 2025–June 2026.

Airline50.5%
Late aircraft22.3%
National airspace20.4%
Weather6.8%
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.