Flight profile · Delta Air Lines
DL429
Seattle (SEA) to New York (JFK) · scheduled 7:10 AM – 3:49 PM
How DL429 performs
785 operations, June 2024 – July 2026.
DL429 arrived on time 87.2% of the time, against 74.8% for all SEA → JFK flights, so this departure is 12.4 percentage points better than the route as a whole. Against Delta Air Lines’ own flights on this route it is 5.3 points better.
Source: US DOT Bureau of Transportation Statistics · 785 operations, June 2024 – July 2026 · If DL429 is cancelled or significantly changed, DOT’s automatic refund rule may entitle you to your money back. The refund checker walks through eligibility.
What stands out
How DL429 compares to other flight numbers, not just to itself.
This flight runs unusually far ahead of the SEA → JFK route as a whole, better than 95% of 11,788 comparable flight numbers.
87.2% on time for this specific departure, against 74.8% for every SEA → JFK flight.
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026 · The one thing about this specific departure that ranks most extreme against every other published flight number, out of everything FlyerIntel checks — shown only when something clears a real statistical bar, not for every flight.
Where DL429 is right now
A live reading, only if you ask for it. It is not part of the reliability record above.
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Against the rest of the route
| Flight or route | On time | Cancelled | Median delay | Severe | Flights |
|---|---|---|---|---|---|
| DL429 | 87.2% | 2.17% | -10 min | 3.0% | 785 |
| Delta Air Lines on SEA → JFK | 81.9% | 1.61% | -9 min | 5.3% | 4,092 |
| All SEA → JFK flights | 74.8% | 1.80% | -5 min | 7.6% | 9,123 |
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026
Why DL429 runs late
Where US DOT attributed the delay minutes on this flight.
crew, maintenance, boarding and fueling, all within the carrier’s control
airspace and airport capacity, including weather-driven flow control
the inbound aircraft was late, so this flight started late
weather severe enough to stop this flight specifically
Share of the delay minutes US DOT attributed to each cause for DL429 on SEA → JFK. Only delays of 15 minutes or more are attributed.
Source: US DOT Bureau of Transportation Statistics · Data covering June 2024 – July 2026
Does a late aircraft delay this flight?
How often the plane that flies DL429 comes in late, and what that does to the departure.
DL429 is usually the aircraft’s first flight of the day: the schedule gives it a median of 8.8 hours on the ground at SEA, so its “inbound” is mostly the aircraft’s arrival the evening before.
When the aircraft came in 15 or more minutes late, DL429 pushed back an average of 10 minutes late; when it came in on time or early, an average of 2 minutes late.
Each departure is matched to the flight the same aircraft flew into SEA just before it, using the tail number in the DOT file, 695 of 768 departures in all. A departure is left out when that flight is unknown, was cancelled or diverted, or the aircraft had sat for more than 12 hours. A flight the airline cancelled never left and is not in the count, and one flown by a substitute aircraft is matched to the aircraft that flew it, not to the one first planned.
Against the network at the same turn length
| Share of departures | Inbound landed 15+ late | Left 15+ late after a late inbound | Left 15+ late after an on-time inbound |
|---|---|---|---|
| DL429 | 25% | 6% | 7% |
| Network, same turn | 29% | 12% | 9% |
A night on the ground absorbs most of a late arrival, so a late inbound matters far less on a turn this long than on a same-day one.
The network row is every flight with a scheduled turn of 6 hours or more, usually overnight. How often DL429’s aircraft landed 15 or more minutes late is lower than the network’s and, once the aircraft was late, how often DL429 left 15 or more minutes late is lower than the network’s.
More: Which Flight Numbers Pay for a Late Aircraft lists the flight numbers that pass a late aircraft on.
Source: US DOT Bureau of Transportation Statistics · Data covering June 2024 – July 2026
From pushback to gate
When it leaves SEA late, does that still matter by the time it reaches JFK?
DL429 pushes back an average of 6.4 minutes late and reaches the gate at JFK an average of 2.2 minutes early. The 8.5 minutes between those two figures are slack the published schedule already carries, which is why a late pushback on this flight does not reliably become a late arrival. It spends 25.8 minutes on the taxiways at SEA, 2.1 minutes longer than a typical SEA departure in the same hour.
On arrival at JFK, DL429 spends 14.6 min taxiing from touchdown to the gate — ground time a connecting passenger sits through before they can even leave the aircraft, on top of however late the flight itself ran. That is 3.2 minutes longer than a typical JFK arrival (11.5 min).
Departure delay is averaged over every pushback and arrival delay over every completed arrival, so the two counts differ by the flights that never reached JFK. Taxi-out is gate to wheels up and sits inside the scheduled block rather than on top of it; the comparison is 42,963 departures from SEA scheduled in the clock hour DL429 most often leaves in. Taxi-in is landing to gate, compared against every arrival FlyerIntel has on file at JFK (351,546 flights), not just DL429’s own. More on taxi time.
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026
The hour it leaves SEA
Part of any flight’s record belongs to the clock rather than to the flight. DL429 has one departure time, so this is what that time is worth.
On-time arrival rate. 42,963 departures from SEA are scheduled in the 7 AM–8 AM hour over the period, against 510,205 across the whole day.
DL429 is scheduled out of SEA at 7:10 AM, in the 7 AM–8 AM bank. Departures from SEA in that hour arrive on time 85.0% of the time against 79.1% across the airport’s whole day — the slot alone is worth 5.9 points better before anything about this particular flight is considered.
The two airport figures cover every departure from SEA to every destination, so they describe the slot rather than this journey — the like-for-like comparison against the route is above. Hours are scheduled local, and a number whose schedule moved between banks inside the period has no single hour and is not described here at all. Why the hour matters.
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026 · Hours below 120 departures are not scored.
Other routes DL429 has flown
A flight number is a slot in a schedule, and carriers reassign it. These are the other city pairs this number served in the analysis period.
| Route | Operated | Flights | On time |
|---|---|---|---|
| JFK→LAX New York to Los Angeles | July 1, 2023 – June 6, 2024 | 243 | 65.1% |
| DTW→LGA Detroit to New York | May 11, 2024 – June 1, 2024 | 4 | — |
| LGA→DFW New York to Dallas–Fort Worth | January 8, 2024 – April 8, 2024 | 88 | — |
| DFW→DTW Dallas–Fort Worth to Detroit | March 16, 2024 – April 6, 2024 | 4 | — |
Because the same number has served different journeys, the statistics above describe only the route DL429 currently operates. Blending them would produce an average of two different flights.
When it goes wrong
The average describes a usual day. This is the day that ruins a connection.
20 min late
against a median of 10 min early
Percentiles over 785 operations; cancelled and diverted flights are counted separately.
Source: US DOT Bureau of Transportation Statistics · Data covering June 2024 – July 2026
Other flights on this route
Same airports, same journey, different odds of arriving on time.
| Flight | Airline | On time | Median arrival | Operations |
|---|---|---|---|---|
| DL429 this flight | Delta Air Lines | 87.2% | 10 min early | 785 |
| DL452 | Delta Air Lines | 83.6% | 9 min early | 781 |
| AS26 | Alaska Airlines | 78.8% | 5 min early | 965 |
| AS22 | Alaska Airlines | 76.5% | 5 min early | 971 |
| DL415 | Delta Air Lines | 75.0% | 6 min early | 781 |
| AS34 | Alaska Airlines | 72.7% | 1 min early | 1,126 |
| B6264 | JetBlue | 62.6% | 2 min late | 674 |
| AS16 | Alaska Airlines | 54.5% | 10 min late | 1,077 |
Every departure listed carries at least 600 operations, so the comparison is between figures that mean something. DL429 is placed in the same ordering rather than left out of it; the rows around it are the most punctual departures on the route, not all of them, so this is a comparison and not a rank. Schedules change; confirm the departure still operates before booking around this.
Data and methodology
Calculated by FlyerIntel from 785 records of DL429 operating SEA → JFK, published by the US DOT Bureau of Transportation Statistics. A flight counts as delayed when it arrives 15 or more minutes after schedule. Cancelled and diverted flights are excluded from the on-time rate and reported separately. Flight numbers are resolved as carrier plus number plus route, because the same number serves different routes over time.
Full methodology · Data sources · Report a problem
Related research: Most and Least Reliable Flight Numbers · The Delay You Inherit · Making Up Time in the Air
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