ON TIMEBOARD
Delta Air Lines / ATL → IAH

DL 1223 on time

Delta Air Lines 1223: Atlanta to Houston at 4:25 p.m.; Houston to Atlanta at 6:37 p.m. (past 12 months). Figures below the title are for ATL → IAH, its busiest leg

On time
67%
183 flights · likely 60–73%
Cancelled
2.2%
of scheduled flights
Typical arrival
−2 min
median vs schedule
When late
+72 min
average delay
Similar flights
60%
DL, same route & hour

About 1 in 3 DL 1223 flights from Atlanta arrived 15+ minutes late, diverted or cancelled over the past year (33%); 2.2% were cancelled. The typical flight landed 2 minutes early.

DL 1223: ATL → IAH

Scheduled to leave Atlanta at 4:25 p.m. local time. Over the past year it arrived on time 67% of the time (183 flights), better than other DL flights on the route at that hour (60%). Last seen in the data Aug 31, 2026.

Month by month

40%70%100%Apr 2025: 77% on time (30 flights)77AprMay 2025: 65% on time (31 flights)65MayJun 2025: too few flights (7 flights)JunDec 2025: too few flights (12 flights)DecJan 2026: 50% on time (28 flights)50JanFeb 2026: 80% on time (25 flights)80FebMar 2026: too few flights (6 flights)MarApr 2026: 89% on time (18 flights)89AprMay 2026: 70% on time (27 flights)70MayJun 2026: 47% on time (17 flights)47JunJul 2026: 50% on time (24 flights)50JulAug 2026: 69% on time (26 flights)69Aug

By day of week

DayFlightsOn time
Monday3165%
Tuesday2763%
Wednesday2781%
Thursday3077%
Friday3057%
Saturday9—
Sunday2959%

Why it was late

Airline (crew, maintenance, ops) 35%Air traffic & airport (NAS) 27%Late inbound plane 25%Severe weather 13%

All flights ATL → IAH · Connecting off DL 1223? Check the risk

DL 1223: IAH → ATL

Scheduled to leave Houston at 6:37 p.m. local time. Over the past year it arrived on time 70% of the time (161 flights), in line with other DL flights on the route at that hour (67%). Last seen in the data Aug 31, 2026.

Usually Delta Air Lines's last flight of the day from Houston to Atlanta (88% of days). Delta Air Lines's last IAH–ATL flight was cancelled 2.7% of the time, against 1.9% for its earlier ones. If it's cancelled, the next Delta Air Lines flight is usually around 5:40 a.m. the next morning.

Month by month

40%70%100%Apr 2025: 77% on time (30 flights)77AprMay 2025: 74% on time (31 flights)74MayJun 2025: too few flights (7 flights)JunDec 2025: too few flights (12 flights)DecJan 2026: 68% on time (28 flights)68JanFeb 2026: 82% on time (28 flights)82FebMar 2026: too few flights (7 flights)MarApr 2026: 89% on time (18 flights)89AprMay 2026: too few flights (6 flights)MayJun 2026: too few flights (12 flights)JunJul 2026: 50% on time (24 flights)50JulAug 2026: 69% on time (26 flights)69Aug

By day of week

DayFlightsOn time
Monday2770%
Tuesday2365%
Wednesday2387%
Thursday2576%
Friday2564%
Saturday13—
Sunday2552%

Why it was late

Late inbound plane 48%Airline (crew, maintenance, ops) 37%Air traffic & airport (NAS) 15%

All flights IAH → ATL · Connecting off DL 1223? Check the risk

Questions

How often is DL 1223 from ATL to IAH late?

Delta Air Lines 1223 from Atlanta, GA to Houston, TX arrived 15 or more minutes late, was diverted or was cancelled on 33% of 183 scheduled flights between September 2025 and August 2026. 2.2% were cancelled.

How often is DL 1223 from IAH to ATL late?

Delta Air Lines 1223 from Houston, TX to Atlanta, GA arrived 15 or more minutes late, was diverted or was cancelled on 30% of 161 scheduled flights between September 2025 and August 2026. 3.1% were cancelled.

Flight numbers change. Figures cover flights with this airline, number and route only. "Likely range" is the 95% interval for the true on-time rate given the number of flights. This is history, not live status: check Delta Air Lines for today's flight. Method.