Flight number record

DL 1638

Delta Air Lines · New York to West Palm Beach

Route: JFK → PBI
Departs: 16:20
Flights: 364
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 1638, check with Delta Air Lines.

DL 1638 sits in the middle of the pack with a C−. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 364 flights, with a median arrival 7 minutes early.

The national on-time rate over the same period is 77.6%, so DL 1638 runs 4 points behind the country as a whole. Across a thousand flights that is about 42 extra late arrivals.

On time

73.4%

Arrivals under 15 minutes late, of 346 completed flights

Avg delay

72 min

Across delayed arrivals only, not all flights

Cancelled

4.67%

National rate is 1.81%

1 hour+ late

11.8%

National rate is 8.1%

These figures cover 364 flights between July 2025 and June 2026. Beyond the headline rate, 11.8% 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 1638 flies

DL 1638 flies JFK to PBI without a single fixed slot. Its most common scheduled departure was 16:20, used on 84 of 364 flights, with 15:25 (56 flights) and 16:00 (53 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 16:2084 flights23.1%
Departs 15:2556 flights15.4%
Departs 16:0053 flights14.6%

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 16:20 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 72.4%, and DL 1638 runs level with that at 73.4%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

Against the route

DL 1638 next to JFK to PBI

Every carrier on JFK to PBI combined arrived on time 74.2% of the time across 2,205 flights, so DL 1638 is about level with it. Delta flew 729 flights on the same city pair under all its flight numbers, including this one, and those ran 80.7% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight trails by 8 points.

DL 1638 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 1638thin sample	364	73.4%	72 min	4.67%	C−
All Delta Air Lines on JFK–PBI	729	80.7%	68 min	4.94%	B−
All carriers on JFK–PBI	2,205	74.2%	71 min	4.04%	C−
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 1638 quarter by quarter

DL 1638 did not run the same all year. Its best quarter was Apr–Jun 2026 at 79.3% on time and its weakest Oct–Dec 2025 at 66.3%, a swing of 13 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 flights75.0%
Oct–Dec 202591 flights66.3%
Jan–Mar 202690 flights72.9%
Apr–Jun 202691 flights79.3%

Scale runs 60% to 85%. Rows with fewer than 30 flights show a dash.

By weekday, DL 1638 did best on Saturday at 83.0% on time and worst on Sunday at 58.3%. Each day rests on about 52 flights, so a gap of 25 points is worth noticing but could still narrow in another year.

Delay causes

Why DL 1638 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 6,643 reported delay minutes.

Late-arriving aircraft
35%
Carrier
35%
National Airspace System
26%
Extreme weather
4%

35% 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 6,643 reported delay minutes here, that single category outweighs weather by 9 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 6,643 delay minutes reported on DL 1638.

Cancellations run at 4.67%, against 1.81% 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

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 11.8% 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 1,028 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.

The same number turns up on one other city pair in the data, including PBI to JFK (137), but none flew often enough under DL 1638 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to JFK to PBI only.

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 1638

For a booking, the cancellation rate is the figure to plan around on DL 1638: 4.67% of its 364 scheduled flights did not operate. A late arrival costs a little over an hour, 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