Flight number record
DL 1139
Delta Air Lines · Atlanta to Chicago
- Route
- ATL → ORD
- Departs
- 20:20
- Flights
- 250
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s DL 1139, check with Delta Air Lines.
DL 1139 earns a D, which is as low as this site's scale goes for a reason. Only 57.1% of flights arrive inside the 15-minute window, 20 points worse than the national rate of 77.6%. Late arrivals average an hour and a half. Treat any tight connection here as a coin flip. That rests on 250 flights, with a median arrival 9 minutes late.
The national on-time rate over the same period is 77.6%, so DL 1139 runs 20 points behind the country as a whole. Across a thousand flights that is about 205 extra late arrivals.
Key figures
On time
57.1%
Arrivals under 15 minutes late, of 245 completed flights
Avg delay
84 min
Across delayed arrivals only, not all flights
Cancelled
1.20%
National rate is 1.81%
1 hour+ late
15.1%
National rate is 8.1%
These figures cover 250 flights between July 2025 and June 2026. Beyond the headline rate, 15.1% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Schedule
When DL 1139 flies
DL 1139 flies ATL to ORD without a single fixed slot. Its most common scheduled departure was 20:20, used on 61 of 250 flights, with 20:10 (31 flights) and 20:16 (30 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 20:2061 flights24.4%
- Departs 20:1031 flights12.4%
- Departs 20:1630 flights12.0%
Scale runs 0% to 100%. Rows with fewer than 30 flights show a dash.
Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.
A 20:20 departure sits in the 8pm–5am window. Across every US flight scheduled in that window the on-time rate is 70.5%, and DL 1139 runs 13 points worse at 57.1%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.
Against the route
DL 1139 next to ATL to ORD
Every carrier on ATL to ORD combined arrived on time 70.6% of the time across 6,406 flights, so DL 1139 is 13 points behind it. Delta flew 2,625 flights on the same city pair under all its flight numbers, including this one, and those ran 69.1% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight trails by 24 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 1139thin sample | 250 | 57.1% | 84 min | 1.20% | D |
| All Delta Air Lines on ATL–ORD | 2,625 | 69.1% | 63 min | 2.21% | C |
| All carriers on ATL–ORD | 6,406 | 70.6% | 81 min | 2.34% | C |
| Delta Air Lines, whole network | 1,038,570 | 81.6% | 71 min | 1.62% | B |
Across the year
DL 1139 quarter by quarter
DL 1139 did not run the same all year. Its best quarter was Jul–Sep 2025 at 67.9% on time and its weakest Jan–Mar 2026 at 40.5%, a swing of 27 points on roughly 63 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.
- Jul–Sep 202586 flights67.9%
- Oct–Dec 202571 flights63.4%
- Jan–Mar 202638 flights40.5%
- Apr–Jun 202655 flights43.4%
Scale runs 30% to 75%. Rows with fewer than 30 flights show a dash.
By weekday, DL 1139 did best on Friday at 64.1% on time and worst on Thursday at 50.0%. Each day rests on about 36 flights, so a gap of 14 points is worth noticing but could still narrow in another year.
Delay causes
Why DL 1139 runs late
One category carries most of the weight here. Carrier accounts for 46% of the 8,858 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 46%Carrier
- 35%National Airspace System
- 11%Extreme weather
- 9%Late-arriving aircraft
The largest share of delay minutes, 46%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 4,042 of the 8,858 delay minutes reported here. The split is drawn from 8,858 delay minutes reported on DL 1139.
Cancellations sit at 1.20% against a national 1.81%, which is ordinary. Diversions add another 0.80%.
Connections and routes
What a delay on this flight costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 15.1% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
The 606 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The same number turns up on one other city pair in the data, including SEA to GEG (24), but none flew often enough under DL 1139 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to ATL to ORD only.
One caution: this is a thin sample. 250 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking DL 1139
For a booking, DL 1139 is a flight to put a long connection behind. 15.1% of its completed flights arrived an hour or more late, which a short layover will not absorb. If the onward flight is on a separate ticket, the risk sits with you.
Related
Where to go next
- ATL to ORD, every carrier and departure
- ORD to ATL, the return direction
- Delta Air Lines 2738 on the same route60.6%
- United Airlines 516 on the same route72.9%
- Delta Air Lines 1147 on the same route79.2%
- Frontier Airlines 1441 on the same route70.8%
- United Airlines 1046 on the same route58.9%
- Delta Air Lines 2879 on the same route46.8%
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Chicago O'Hare International (ORD) delay statistics
- Delta Air Lines on-time record
- Every Delta Air Lines flight number with a record
- The most and least reliable flight numbers in the US
- How often a connection fails at the major US hubs
A flight number here means Delta Air Lines’s own number as it reports to the DOT. How the figures are computed is on the methodology page.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.