Flight number record

DL 688

Delta Air Lines · New York to Seattle

Route: JFK → SEA
Departs: 18:59
Flights: 359
Period: September 2025 to August 2026

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

DL 688 draws a D−. 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 3 minutes late.

The national on-time rate over the same period is 77.3%, so DL 688 runs 13 points behind the country as a whole. Across a thousand flights that is about 129 extra late arrivals.

On time

64.4%

Arrivals under 15 minutes late, of 343 completed flights

Avg delay

62 min

Across delayed arrivals only, not all flights

Cancelled

3.90%

National rate is 1.89%

1 hour+ late

11.4%

National rate is 8.3%

These figures cover 359 flights between September 2025 and August 2026. Beyond the headline rate, 11.4% of arrivals land a full hour or more behind schedule, against 8.3% nationally.

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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 19:35 (37 flights) next.

Departs 18:59111 flights30.9%
Departs 19:0080 flights22.3%
Departs 19:3537 flights10.3%

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 18:59 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.0%, and DL 688 runs 4 points worse at 64.4%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.

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Against the route

DL 688 next to JFK to SEA

Every carrier on JFK to SEA combined arrived on time 69.5% of the time across 2,906 flights, so DL 688 is 5 points behind it. Delta flew 1,339 flights on the same city pair under all its flight numbers, including this one, and those ran 71.4% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight trails by 17 points.

DL 688 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 688thin sample	359	64.4%	62 min	3.90%	D−
All Delta Air Lines on JFK–SEA	1,339	71.4%	60 min	3.21%	C−
All carriers on JFK–SEA	2,906	69.5%	65 min	3.44%	C−
Delta Air Lines, whole network	1,039,517	81.1%	71 min	1.74%	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 83.3% on time and its weakest Oct–Dec 2025 at 44.6%, a swing of 39 points on roughly 72 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 flights83.3%
Oct–Dec 202587 flights44.6%
Jan–Mar 202689 flights68.3%
Apr–Jun 202691 flights71.1%
Jul–Sep 202662 flights67.2%

Scale runs 35% to 90%.

By weekday, DL 688 did best on Tuesday at 74.0% on time and worst on Thursday at 55.3%. Each day rests on about 51 flights, so a gap of 19 points is worth noticing but could still narrow in another year.

Arrival by arrival

How late DL 688 runs when it is late

DL 688 often beats the schedule: 89 of 343 completed flights, 26%, arrived 15 minutes or more early. The 122 late arrivals split 45 under half an hour, 38 between 30 and 60 minutes, and 39 an hour or more.

15+ min early89 flights25.9%
Within 15 min132 flights38.5%
15–29 min late45 flights13.1%
30–59 min late38 flights11.1%
1–2 hours late26 flights7.6%
2+ hours late13 flights3.8%

Scale runs 0% to 100%.

Share of 343 completed flights by arrival against schedule.

A late pushback is often recovered here: of 99 departures that left 15 minutes late or more, 32 still arrived on time. In the other direction, 55 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at SEA.

The worst days

Worst days for DL 688

The latest arrival of the period was on 6 June 2026, 14 hours 57 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The five worst days are spread across June, December, August and May, with no single month standing out.

The latest arrivals of DL 688 in the period
Date	Arrived late by	Largest filed cause
6 June 2026	14 hours 57 minutes	Carrier
23 December 2025	3 hours 50 minutes	Late-arriving aircraft
27 August 2026	3 hours	National Airspace System
19 May 2026	2 hours 52 minutes	Carrier
14 August 2026	2 hours 44 minutes	Late-arriving aircraft

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 7,520 reported delay minutes.

National Airspace System
41%
Carrier
35%
Late-arriving aircraft
20%
Extreme weather
4%

41% 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 3,074 minutes out of 7,520, against a national NAS share of 21%. The split is drawn from 7,520 delay minutes reported on DL 688.

Cancellations run at 3.90%, against 1.89% nationally. That is about one flight in 25 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

11.4% 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 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: 3.90% 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, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures