Flight profile · Delta Air Lines
DL939
Los Angeles (LAX) to New York (JFK) · scheduled 12:00 PM – 9:50 PM
How DL939 performs
699 operations, June 2024 – July 2026.
DL939 arrived on time 72.7% of the time, against 79.8% for all LAX → JFK flights, so this departure is 7.1 percentage points worse than the route as a whole. Against Delta Air Lines’ own flights on this route it is 6.9 points worse.
Source: US DOT Bureau of Transportation Statistics · 699 operations, June 2024 – July 2026 · If DL939 is cancelled or significantly changed, DOT’s automatic refund rule may entitle you to your money back. The refund checker walks through eligibility.
Where DL939 is right now
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Against the rest of the route
| Flight or route | On time | Cancelled | Median delay | Severe | Flights |
|---|---|---|---|---|---|
| DL939 | 72.7% | 0.86% | -6 min | 12.7% | 699 |
| Delta Air Lines on LAX → JFK | 79.6% | 1.03% | -9 min | 7.5% | 10,288 |
| All LAX → JFK flights | 79.8% | 1.27% | -10 min | 8.3% | 31,153 |
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026
Why DL939 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
screening or terminal security incidents
weather severe enough to stop this flight specifically
Share of the delay minutes US DOT attributed to each cause for DL939 on LAX → 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 DL939 comes in late, and what that does to the departure.
When the aircraft came in 15 or more minutes late, DL939 pushed back an average of 64 minutes late; when it came in on time or early, an average of 9 minutes late.
Each departure is matched to the flight the same aircraft flew into LAX just before it, using the tail number in the DOT file, 636 of 693 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 |
|---|---|---|---|
| DL939 | 21% | 82% | 18% |
| Network, same turn | 17% | 68% | 9% |
The schedule leaves a normal turn: enough time to clean and board if the aircraft is on time, little to spare if it is not.
The network row is every flight with a scheduled turn of 60 to 89 minutes. How often DL939’s aircraft landed 15 or more minutes late is higher than the network’s and, once the aircraft was late, how often DL939 left 15 or more minutes late is higher 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 LAX late, does that still matter by the time it reaches JFK?
DL939 pushes back an average of 25.7 minutes late and reaches the gate at JFK an average of 12.3 minutes late. The 13.4 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 18.7 minutes on the taxiways at LAX, 1.2 minutes longer than a typical LAX departure in the same hour.
On arrival at JFK, DL939 spends 16.1 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 4.7 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 28,678 departures from LAX scheduled in the clock hour DL939 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 DL939’s own. More on taxi time.
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026
The hour it leaves LAX
Part of any flight’s record belongs to the clock rather than to the flight. DL939 has one departure time, so this is what that time is worth.
On-time arrival rate. 28,678 departures from LAX are scheduled in the 12 PM–1 PM hour over the period, against 595,153 across the whole day.
DL939 is scheduled out of LAX at 12:00 PM, in the 12 PM–1 PM bank. Departures from LAX in that hour arrive on time 78.1% of the time against 81.4% across the airport’s whole day — the slot alone is worth 3.3 points worse before anything about this particular flight is considered.
The two airport figures cover every departure from LAX 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 DL939 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 |
|---|---|---|---|
| ATL→LGA Atlanta to New York | July 1, 2023 – June 6, 2024 | 197 | 74.7% |
| BOS→LAS Boston to Las Vegas | March 10, 2024 – May 6, 2024 | 34 | — |
| JFK→DEN New York to Denver | March 12, 2024 – April 6, 2024 | 12 | — |
| SEA→MCO Seattle to Orlando | January 8, 2024 – March 9, 2024 | 62 | — |
| MCO→SEA Orlando to Seattle | January 15, 2024 – March 9, 2024 | 28 | — |
Because the same number has served different journeys, the statistics above describe only the route DL939 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.
75 min late
against a median of 6 min early
DL939 has an average that understates its risk: a typical arrival is 6 min early, but the worst tenth are 81 minutes worse than that. If the trip has something unmissable at the end of it, the median is the wrong number to plan against.
Percentiles over 699 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 |
|---|---|---|---|---|
| AA118 | American Airlines | 89.6% | 17 min early | 1,122 |
| AA10 | American Airlines | 89.5% | 18 min early | 1,095 |
| B62824 | JetBlue | 88.7% | 14 min early | 658 |
| DL934 | Delta Air Lines | 88.2% | 10 min early | 876 |
| DL979 | Delta Air Lines | 87.2% | 13 min early | 783 |
| DL915 | Delta Air Lines | 84.7% | 11 min early | 727 |
| AA2 | American Airlines | 84.2% | 15 min early | 1,121 |
| DL960 | Delta Air Lines | 82.4% | 9 min early | 850 |
| DL939 this flight | Delta Air Lines | 72.7% | 6 min early | 699 |
Every departure listed carries at least 600 operations, so the comparison is between figures that mean something. DL939 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 699 records of DL939 operating LAX → 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
Analysis last recomputed