Flight number record
DL 1166
Delta Air Lines · San Antonio to New York
- Route
- SAT → JFK
- Departs
- 12:37
- Flights
- 362
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 1166, check with Delta Air Lines.
DL 1166 lands a B−, 3 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by close to two hours on average. That rests on 362 flights, with a median arrival 9 minutes early.
Key figures
On time
79.9%
Arrivals under 15 minutes late, of 343 completed flights
Avg delay
112 min
Across delayed arrivals only, not all flights
Cancelled
4.70%
National rate is 1.89%
1 hour+ late
9.9%
National rate is 8.3%
These figures cover 362 flights between September 2025 and August 2026. Beyond the headline rate, 9.9% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When DL 1166 flies
DL 1166 flies SAT to JFK without a single fixed slot. Its most common scheduled departure was 12:37, used on 56 of 362 flights, with 12:55 (53 flights) and 12:10 (37 flights) next.
- Departs 12:3756 flights15.5%
- Departs 12:5553 flights14.6%
- Departs 12:1037 flights10.2%
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 12:37 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.3%, and DL 1166 runs level with that at 79.9%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.
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Against the route
DL 1166 next to SAT to JFK
Across its whole network Delta Air Lines managed 81.1%, close to this flight's figure.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 1166thin sample | 362 | 79.9% | 112 min | 4.70% | B− |
| All Delta Air Lines on SAT–JFKthin sample | 362 | 79.9% | 112 min | 4.70% | B− |
| All carriers on SAT–JFKthin sample | 362 | 79.9% | 112 min | 4.70% | B− |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 1166 quarter by quarter
DL 1166 did not run the same all year. Its best quarter was Apr–Jun 2026 at 82.4% on time and its weakest Jul–Sep 2026 at 66.7%, a swing of 16 points on roughly 91 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 flights—
- Oct–Dec 202590 flights81.4%
- Jan–Mar 202689 flights81.2%
- Apr–Jun 202691 flights82.4%
- Jul–Sep 202662 flights66.7%
Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.
By weekday, DL 1166 ranged from 75.0% on Sunday to 84.3% on Wednesday. With about 52 flights behind each day, a spread of 9 points is inside normal variation, so the day you fly is not worth changing for this flight.
Arrival by arrival
How late DL 1166 runs when it is late
DL 1166 often beats the schedule: 129 of 343 completed flights, 38%, arrived 15 minutes or more early. The 69 late arrivals split 20 under half an hour, 15 between 30 and 60 minutes, and 34 an hour or more.
- 15+ min early129 flights37.6%
- Within 15 min145 flights42.3%
- 15–29 min late20 flights5.8%
- 30–59 min late15 flights4.4%
- 1–2 hours late16 flights4.7%
- 2+ hours late18 flights5.2%
Scale runs 0% to 100%.
Share of 343 completed flights by arrival against schedule.
10 of 63 late departures made up the time and arrived on time, 16% of them. 16 flights left on time and still arrived late.
The worst days
Worst days for DL 1166
The latest arrival of the period was on 26 December 2025, 16 hours 38 minutes behind schedule; most of its delay minutes were filed as national airspace system delay. The five worst days are spread across December, October, April, August and January, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 26 December 2025 | 16 hours 38 minutes | National Airspace System |
| 30 October 2025 | 9 hours 56 minutes | Extreme weather |
| 9 April 2026 | 8 hours 23 minutes | Late-arriving aircraft |
| 11 August 2026 | 7 hours 29 minutes | Extreme weather |
| 27 January 2026 | 6 hours 18 minutes | Late-arriving aircraft |
Delay causes
Why DL 1166 runs late
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 7,742 reported delay minutes.
- 38%Late-arriving aircraft
- 33%National Airspace System
- 15%Extreme weather
- 14%Carrier
Extreme weather accounts for 15% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the quarterly figures above are the more useful view of the risk. The national share is 6%, so this operation carries roughly 2.5 times the usual weather exposure. The split is drawn from 7,742 delay minutes reported on DL 1166.
Cancellations run at 4.70%, against 1.89% nationally. That is about one flight in twenty cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.
Connections and routes
What a delay on this flight costs
9.9% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
At 1,587 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
DL 1166 is not only a SAT to JFK flight. It also flew JFK to SAT (340 flights, 87.0% 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. 362 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 |
|---|---|---|---|---|---|
| JFK to SATthin sample | 340 | 87.0% | 99 min | 4.71% | A− |
What to do with this
Booking DL 1166
For a booking, the cancellation rate is the figure to plan around on DL 1166: 4.70% of its 362 scheduled flights did not operate. A late arrival costs close to two hours, but a cancellation costs the day, so leave a later option open.
Related
Where to go next
- San Antonio International (SAT) delay statistics
- John F. Kennedy International (JFK) 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.