Flight number record
DL 1178
Delta Air Lines · Chicago to Atlanta
- Route
- ORD → ATL
- Departs
- 09:50
- Flights
- 347
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s DL 1178, check with Delta Air Lines.
DL 1178 earns an A. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 10 points better than the national rate of 77.6%. When something does go wrong the average delay runs roughly 50 minutes. That rests on 347 flights, with a median arrival 12 minutes early.
Set against the rest of the country, DL 1178's record is 10 points better than the US average of 77.6%. That gap is worth roughly 95 fewer late arrivals for every thousand flights.
Key figures
On time
87.1%
Arrivals under 15 minutes late, of 340 completed flights
Avg delay
49 min
Across delayed arrivals only, not all flights
Cancelled
2.02%
National rate is 1.81%
1 hour+ late
2.6%
National rate is 8.1%
These figures cover 347 flights between July 2025 and June 2026. The median arrival is 12 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
Schedule
When DL 1178 flies
DL 1178 flies ORD to ATL without a single fixed slot. Its most common scheduled departure was 09:50, used on 94 of 347 flights, with 09:49 (47 flights) and 09:48 (46 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 09:5094 flights27.1%
- Departs 09:4947 flights13.5%
- Departs 09:4846 flights13.3%
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 09:50 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 84.1%, and DL 1178 runs 3 points better at 87.1%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
Against the route
DL 1178 next to ORD to ATL
Every carrier on ORD to ATL combined arrived on time 75.0% of the time across 6,409 flights, so DL 1178 is 12 points ahead of it. Delta flew 2,623 flights on the same city pair under all its flight numbers, including this one, and those ran 80.4% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight beats by 6 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 1178thin sample | 347 | 87.1% | 49 min | 2.02% | A |
| All Delta Air Lines on ORD–ATL | 2,623 | 80.4% | 87 min | 2.36% | B |
| All carriers on ORD–ATL | 6,409 | 75.0% | 81 min | 2.26% | B |
| Delta Air Lines, whole network | 1,038,570 | 81.6% | 71 min | 1.62% | B |
Across the year
DL 1178 quarter by quarter
DL 1178 did not run the same all year. Its best quarter was Jul–Sep 2025 at 93.4% on time and its weakest Oct–Dec 2025 at 80.5%, a swing of 13 points on roughly 87 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 202591 flights93.4%
- Oct–Dec 202588 flights80.5%
- Jan–Mar 202677 flights87.7%
- Apr–Jun 202691 flights86.5%
Scale runs 70% to 100%. Rows with fewer than 30 flights show a dash.
By weekday, DL 1178 ranged from 80.9% on Sunday to 92.5% on Saturday. With about 50 flights behind each day, a spread of 12 points is inside normal variation, so the day you fly is not worth changing for this flight.
Delay causes
Why DL 1178 runs late
One category carries most of the weight here. Late-arriving aircraft accounts for 48% of the 2,133 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.
- 48%Late-arriving aircraft
- 28%National Airspace System
- 15%Carrier
- 9%Extreme weather
48% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 2,133 reported delay minutes here, that single category outweighs weather by 5 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 2,133 delay minutes reported on DL 1178.
Cancellations sit at 2.02% against a national 1.81%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
Badly late arrivals are rare here: only 2.6% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
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.
DL 1178 is not only a ORD to ATL flight. It also flew ATL to ORD (332 flights, 88.0% on time) often enough to be scored on its own. Airlines attach one number to several legs of an aircraft's day, and each leg keeps its own record here, so check which city pair is on your booking before reading a rate.
One caution: this is a thin sample. 347 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.
| Also flown as | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| ATL to ORDthin sample | 332 | 88.0% | 49 min | 2.41% | A |
What to do with this
Booking DL 1178
For a booking, read DL 1178 as 87.1% on time with 2.02% cancelled over 347 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- ORD to ATL, every carrier and departure
- ATL to ORD, the return direction
- Delta Air Lines 1264 on the same route91.1%
- Delta Air Lines 1247 on the same route87.2%
- Delta Air Lines 1147 on the same route79.9%
- United Airlines 356 on the same route74.2%
- Frontier Airlines 1596 on the same route74.8%
- Delta Air Lines 2738 on the same route65.4%
- Chicago O'Hare International (ORD) delay statistics
- Hartsfield-Jackson Atlanta International (ATL) 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
- Why the first flight of the morning is statistically safest
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.