DL3987Delta Air Lines · SEA → ONT
live · 1h ago
Route confirmed Delta Air Lines

DL3987 SeattleSEA · 19:56 OntarioONT · 22:43

DL3987 by Delta Air Lines flies from Seattle (SEA) to Ontario (ONT) for the Sat, Oct 31 departure.

Right nowOn time · gate B4 · as of 02:01
19:56

departs SEA · on schedule

Typical arrival−8 minmedian over 4 operations

Where the minutes go

last 4 operations · gate push → arrival
0+30+60+90 min
10-30
−6 arrival
10-29
−8 arrival
10-28
−20 arrival
10-27
−8 arrival

The bar is how late it left the gate; the ring is where it actually arrived. Board clocks, not estimates.

The route today

live boards
SEASeattleOn-time likelySEA delay board →
ONTOntarioOn-time likelyONT delay board →
SEA→ONTevery carrier, schedules and on-time historyRoute intelligence →

Weather lens

Delay & cancellation outlook for this flight

Measured, 90-day sample
39%Chance of 15+ min delay
0.8%Chance of cancellation
+8 minTypical airport delay in this weather

Conditions at SEA and ONT are near their clear-air norm right now, so this reflects the route's recent baseline rather than a weather penalty. These figures come from both airports' records under conditions like today's, over the last 90 days.

Pro Flight Search tracking, 90 days · the weather × delay correlation study → · live weather risk by airport →

Tomorrow on this route

Forecast

Seattle to Ontario with Delta Air Lines · Sun 1 Nov, local date

Outlook: about usual
Chance a departure is cancelled
0.3%0.9× usual
Chance a departure leaves 60+ min late
7.8%0.9× usual

Forecast weather: 84% chance of rain at Ontario

Forecast: WeatherTomorrow · incl. data from ECMWF (CC BY 4.0, modified) · About 3 departures a day on this route with this airline. · Expected values for tomorrow from a forecast model, kept apart from today's measured figures.

When it flies

scheduled departures
061422
M
T
W
T
F
S
S

Each mark is a scheduled departure at its origin-local time. Today is highlighted.

Other Seattle to Ontario flights today

same route · Delta Air Lines
DL4070departs 08:25
DL4031departs 14:30

If DL3987 is cancelled, these are the other Delta Air Lines nonstop flights from Seattle to Ontario on the same day, with scheduled departure times in SEA local time. Most flights that show a delay still operate. Rebooking usually helps only when that delay is very large. Every airline on this route →

How DL3987 actually runs

Pro Flight Search has tracked every published board update for DL3987 across the SEA and ONT boards: schedule changes, gate pushes and actual clocks. Early read: no clear pattern yet. Only 3 completed legs so far: landed -5 min. Not enough to call it.

The verdict above is that record speaking, so it reflects how DL3987 operates rather than what the timetable promises. Numbers refresh as new flights operate.

Technical record

How this operation is measured

board clocksaircraft

Board log

scheduled → actual, per operation
10-30SEA 19:56ONT 22:43 22:37 (−6)
10-29SEA 19:56ONT 22:43 22:35 (−8)
10-28SEA 19:56ONT 22:43 22:23 (−20)
10-27SEA 19:56ONT 22:43 22:35 (−8)

Aircraft

Recent tails: N286SY, N298SY, N281SY.

Board clocks recorded as SEA and ONT published them.

Planning around DL3987? Will a delayed flight be cancelled? · Do planes make up time in the air? · How we measure

Cite this data

Journalists, bloggers, and researchers may cite this page with attribution and a link to Pro Flight Search.

Suggested citation

Pro Flight Search: DL3987 Seattle to Ontario on-time performance, measured from the SEA and ONT airport boards.

Canonical URL
https://proflightsearch.com/flight/DL3987
How we measure this →