Flight number record

DL 1178

Delta Air Lines · Chicago to Atlanta

Route: ORD → ATL
Departs: 09:50
Flights: 344
Period: September 2025 to August 2026

Historical statistics for September 2025 to August 2026, not live status. For today’s DL 1178, check with Delta Air Lines.

DL 1178 earns an A. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 8 points better than the national rate of 77.3%. When something does go wrong the average delay runs about 50 minutes. That rests on 344 flights, with a median arrival 13 minutes early.

Set against the rest of the country, DL 1178's record is 8 points better than the US average of 77.3%. That gap is worth roughly 81 fewer late arrivals for every thousand flights.

On time

85.4%

Arrivals under 15 minutes late, of 336 completed flights

Avg delay

50 min

Across delayed arrivals only, not all flights

Cancelled

2.33%

National rate is 1.89%

1 hour+ late

3.6%

National rate is 8.3%

These figures cover 344 flights between September 2025 and August 2026. The median arrival is 13 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.

Fare search by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.

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 59 of 344 flights, with 09:48 (52 flights) and 09:49 (42 flights) next.

Departs 09:5059 flights17.2%
Departs 09:4852 flights15.1%
Departs 09:4942 flights12.2%

Scale runs 0% to 100%.

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 83.9%, and DL 1178 runs level with that at 85.4%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.

Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.

Against the route

DL 1178 next to ORD to ATL

Every carrier on ORD to ATL combined arrived on time 74.1% of the time across 6,495 flights, so DL 1178 is 11 points ahead of it. Delta flew 2,629 flights on the same city pair under all its flight numbers, including this one, and those ran 79.8% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight beats by 4 points.

DL 1178 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 1178thin sample	344	85.4%	50 min	2.33%	A
All Delta Air Lines on ORD–ATL	2,629	79.8%	84 min	2.40%	B
All carriers on ORD–ATL	6,495	74.1%	81 min	2.31%	C
Delta Air Lines, whole network	1,039,517	81.1%	71 min	1.74%	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 93.3% on time and its weakest Oct–Dec 2025 at 80.5%, a swing of 13 points on roughly 69 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 202530 flights93.3%
Oct–Dec 202588 flights80.5%
Jan–Mar 202677 flights87.7%
Apr–Jun 202691 flights86.5%
Jul–Sep 202658 flights84.2%

Scale runs 70% to 100%.

By weekday, DL 1178 did best on Thursday at 92.2% on time and worst on Sunday at 78.7%. Each day rests on about 49 flights, so a gap of 14 points is worth noticing but could still narrow in another year.

Arrival by arrival

How late DL 1178 runs when it is late

DL 1178 often beats the schedule: 160 of 336 completed flights, 48%, arrived 15 minutes or more early. Most of the lateness is short. 25 of the 49 late arrivals were under half an hour behind, and 12 reached an hour or more.

15+ min early160 flights47.6%
Within 15 min127 flights37.8%
15–29 min late25 flights7.4%
30–59 min late12 flights3.6%
1–2 hours late8 flights2.4%
2+ hours late4 flights1.2%

Scale runs 0% to 100%.

Share of 336 completed flights by arrival against schedule.

A late pushback is often recovered here: of 46 departures that left 15 minutes late or more, 14 still arrived on time. In the other direction, 17 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at ATL.

The worst days

Worst days for DL 1178

The latest arrival of the period was on 7 December 2025, 4 hours 23 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The five worst days are spread across December, May, August, November and March, with no single month standing out.

The latest arrivals of DL 1178 in the period
Date	Arrived late by	Largest filed cause
7 December 2025	4 hours 23 minutes	Late-arriving aircraft
18 May 2026	4 hours 18 minutes	Extreme weather
12 August 2026	3 hours 2 minutes	Carrier
9 November 2025	2 hours 1 minute	Carrier
6 March 2026	1 hour 26 minutes	National Airspace System

Delay causes

Why DL 1178 runs late

Late-arriving aircraft accounts for 44% of the 2,462 delay minutes carriers reported here, and the remaining four split what is left.

Late-arriving aircraft
44%
National Airspace System
29%
Carrier
19%
Extreme weather
8%

44% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 2,462 reported delay minutes here, that single category outweighs weather by 5 to one. The split is drawn from 2,462 delay minutes reported on DL 1178.

Cancellations sit at 2.33% against a national 1.89%, 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 3.6% land an hour or more behind schedule, against 8.3% 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.

DL 1178 is not only a ORD to ATL flight. It also flew ATL to ORD (325 flights, 87.4% 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. 344 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.

Other routes flown as DL 1178
Also flown as	Flights	On time	Avg delay	Cancelled	Grade
ATL to ORDthin sample	325	87.4%	49 min	2.46%	A

What to do with this

Booking DL 1178

For a booking, read DL 1178 as 85.4% on time with 2.33% cancelled over 344 flights. Those are rates from the past twelve months, not a forecast for any particular day.

Where to go next

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, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures