Flight number record

DL 1166

Delta Air Lines · San Antonio to New York

Route: SAT → JFK
Departs: 12:55
Flights: 362
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 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 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by close to two hours on average. That is a workable record, not a spotless one. That rests on 362 flights, with a median arrival 9 minutes early.

On time

80.4%

Arrivals under 15 minutes late, of 347 completed flights

Avg delay

110 min

Across delayed arrivals only, not all flights

Cancelled

3.31%

National rate is 1.81%

1 hour+ late

9.5%

National rate is 8.1%

These figures cover 362 flights between July 2025 and June 2026. Beyond the headline rate, 9.5% 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 1166 flies

DL 1166 flies SAT to JFK without a single fixed slot. Its most common scheduled departure was 12:55, used on 53 of 362 flights, with 12:10 (37 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 12:5553 flights14.6%
Departs 12:1037 flights10.2%

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 12:55 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.8%, and DL 1166 runs level with that at 80.4%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

Against the route

DL 1166 next to SAT to JFK

Across its whole network Delta Air Lines managed 81.6%, close to this flight's figure.

DL 1166 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 1166thin sample	362	80.4%	110 min	3.31%	B−
All Delta Air Lines on SAT–JFKthin sample	362	80.4%	110 min	3.31%	B−
All carriers on SAT–JFKthin sample	362	80.4%	110 min	3.31%	B−
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 1166 quarter by quarter

Quarter by quarter DL 1166 held fairly steady: 76.7% in Jul–Sep 2025, 81.4% in Oct–Dec 2025, 81.2% in Jan–Mar 2026 and 82.4% in Apr–Jun 2026. A spread of 6 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Jul–Sep 202592 flights76.7%
Oct–Dec 202590 flights81.4%
Jan–Mar 202689 flights81.2%
Apr–Jun 202691 flights82.4%

Scale runs 70% to 90%. Rows with fewer than 30 flights show a dash.

By weekday, DL 1166 did best on Saturday at 89.4% on time and worst on Thursday at 72.5%. Each day rests on about 52 flights, so a gap of 17 points is worth noticing but could still narrow in another year.

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 7,464 reported delay minutes.

Late-arriving aircraft
38%
National Airspace System
33%
Extreme weather
16%
Carrier
12%

Extreme weather accounts for 16% 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 2.6 times the usual weather exposure. The split is drawn from 7,464 delay minutes reported on DL 1166.

Cancellations run at 3.31%, against 1.81% nationally. That is about one flight in 30 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

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.5% 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.

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, 89.9% 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.

Other routes flown as DL 1166
Also flown as	Flights	On time	Avg delay	Cancelled	Grade
JFK to SATthin sample	340	89.9%	119 min	3.24%	A−

What to do with this

Booking DL 1166

For a booking, the cancellation rate is the figure to plan around on DL 1166: 3.31% 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.

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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures