Flight number record

DL 688

Delta Air Lines · New York to Seattle

Route: JFK → SEA
Departs: 18:59
Flights: 359
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 688, check with Delta Air Lines.

DL 688 draws a C. About one flight in three arrives at least 15 minutes late, and the typical late arrival is about an hour behind schedule. Build slack into anything you connect to. That rests on 359 flights, with a median arrival 2 minutes late.

The national on-time rate over the same period is 77.6%, so DL 688 runs 12 points behind the country as a whole. Across a thousand flights that is about 116 extra late arrivals.

On time

66.0%

Arrivals under 15 minutes late, of 347 completed flights

Avg delay

61 min

Across delayed arrivals only, not all flights

Cancelled

2.79%

National rate is 1.81%

1 hour+ late

10.4%

National rate is 8.1%

These figures cover 359 flights between July 2025 and June 2026. Beyond the headline rate, 10.4% 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 688 flies

DL 688 flies JFK to SEA without a single fixed slot. Its most common scheduled departure was 18:59, used on 111 of 359 flights, with 19:00 (80 flights) and 19:05 (36 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 18:59111 flights30.9%
Departs 19:0080 flights22.3%
Departs 19:0536 flights10.0%

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 18:59 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.2%, and DL 688 runs 2 points worse at 66.0%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.

Against the route

DL 688 next to JFK to SEA

Every carrier on JFK to SEA combined arrived on time 69.7% of the time across 2,906 flights, so DL 688 is 4 points behind it. Delta flew 1,338 flights on the same city pair under all its flight numbers, including this one, and those ran 73.2% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight trails by 16 points.

DL 688 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 688thin sample	359	66.0%	61 min	2.79%	C
All Delta Air Lines on JFK–SEA	1,338	73.2%	57 min	2.32%	C
All carriers on JFK–SEA	2,906	69.7%	61 min	2.58%	C
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 688 quarter by quarter

DL 688 did not run the same all year. Its best quarter was Jul–Sep 2025 at 78.3% on time and its weakest Oct–Dec 2025 at 44.6%, a swing of 34 points on roughly 90 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 flights78.3%
Oct–Dec 202587 flights44.6%
Jan–Mar 202689 flights68.3%
Apr–Jun 202691 flights71.1%

Scale runs 35% to 85%. Rows with fewer than 30 flights show a dash.

By weekday, DL 688 did best on Tuesday at 75.0% on time and worst on Thursday at 56.2%. Each day rests on about 51 flights, so a gap of 19 points is worth noticing but could still narrow in another year.

Delay causes

Why DL 688 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 7,153 reported delay minutes.

National Airspace System
39%
Carrier
37%
Late-arriving aircraft
19%
Extreme weather
4%

39% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 2,815 minutes out of 7,153, against a national NAS share of 21%. The split is drawn from 7,153 delay minutes reported on DL 688.

Cancellations run at 2.79%, against 1.81% nationally. That is roughly one flight in 40 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. 10.4% 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 2,422 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.

Every one of the 359 flights under DL 688 in the data flew JFK to SEA. 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. 359 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 688

For a booking, the cancellation rate is the figure to plan around on DL 688: 2.79% of its 359 scheduled flights did not operate. A late arrival costs about 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