Flight number record

DL 999

Delta Air Lines · New York to Detroit

Route: LGA → DTW
Departs: 16:59
Flights: 364
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 999, check with Delta Air Lines.

DL 999 sits in the middle of the pack with a C−. About seven flights in ten arrive on time by the DOT's definition, 6 points worse than the national rate of 77.6%. The late ones land an hour and a half behind schedule. That rests on 364 flights, with a median arrival 5 minutes early.

The national on-time rate over the same period is 77.6%, so DL 999 runs 6 points behind the country as a whole. Across a thousand flights that is about 58 extra late arrivals.

On time

71.8%

Arrivals under 15 minutes late, of 351 completed flights

Avg delay

95 min

Across delayed arrivals only, not all flights

Cancelled

3.57%

National rate is 1.81%

1 hour+ late

12.8%

National rate is 8.1%

These figures cover 364 flights between July 2025 and June 2026. Beyond the headline rate, 12.8% 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 999 flies

DL 999 flies LGA to DTW without a single fixed slot. Its most common scheduled departure was 16:59, used on 98 of 364 flights, with 17:05 (64 flights) and 17:00 (48 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 16:5998 flights26.9%
Departs 17:0564 flights17.6%
Departs 17:0048 flights13.2%

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 16:59 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 72.4%, and DL 999 runs level with that at 71.8%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

Against the route

DL 999 next to LGA to DTW

Every carrier on LGA to DTW combined arrived on time 78.0% of the time across 4,011 flights, so DL 999 is 6 points behind it. Delta flew 1,980 flights on the same city pair under all its flight numbers, including this one, and those ran 81.1% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight trails by 10 points.

DL 999 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 999thin sample	364	71.8%	95 min	3.57%	C−
All Delta Air Lines on LGA–DTW	1,980	81.1%	85 min	3.54%	B−
All carriers on LGA–DTW	4,011	78.0%	82 min	4.94%	B−
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 999 quarter by quarter

DL 999 did not run the same all year. Its best quarter was Jan–Mar 2026 at 80.5% on time and its weakest Oct–Dec 2025 at 64.8%, 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 202592 flights71.3%
Oct–Dec 202591 flights64.8%
Jan–Mar 202690 flights80.5%
Apr–Jun 202691 flights70.8%

Scale runs 55% to 85%. Rows with fewer than 30 flights show a dash.

By weekday, DL 999 did best on Tuesday at 79.2% on time and worst on Sunday at 62.5%. 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 999 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 9,425 reported delay minutes.

Late-arriving aircraft
39%
National Airspace System
35%
Carrier
26%
Security
0%

39% 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 9,425 reported delay minutes here, that single category outweighs weather by 39 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 9,425 delay minutes reported on DL 999.

Cancellations run at 3.57%, 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. 12.8% 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 502 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.

Every one of the 364 flights under DL 999 in the data flew LGA to DTW. The number was not reused on any other city pair, which makes this a clean record of one route.

One caution: this is a thin sample. 364 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 999

For a booking, the cancellation rate is the figure to plan around on DL 999: 3.57% of its 364 scheduled flights did not operate. A late arrival costs an hour and a half, 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